health of rivers essay

Loading metrics

Open Access

Peer-reviewed

Research Article

The future of global river health monitoring

Roles Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected] (LMK); [email protected] (CD); [email protected] (DT)

Affiliation Omfishient Consulting, Bremerton, Washington, United States of America

Roles Conceptualization, Funding acquisition, Investigation, Project administration, Supervision, Writing – review & editing

Affiliation International Water Management Institute, Silverton, South Africa

Roles Conceptualization, Funding acquisition, Writing – review & editing

Affiliation WWF-UK, Living Planet Centre, Woking, United Kingdom

Roles Data curation, Investigation, Visualization, Writing – review & editing

Affiliations Department of Geography, McGill University, Montreal, Québec, Canada, National Research Institute for Agriculture, Food and Environment (INRAE), RiverLy Research Unit, Centre Lyon-Grenoble Auvergne-Rhône-Alpes, Villeurbanne, France

Roles Visualization, Writing – review & editing

Affiliations School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, United States of America, Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden

Affiliation School of Biology and Environmental Sciences, Faculty of Agriculture and Natural Sciences, University of Mpumalanga, Nelspruit, South Africa

Roles Writing – original draft, Writing – review & editing

Affiliation Department of Geography, McGill University, Montreal, Québec, Canada

Roles Investigation, Writing – review & editing

• Lauren M. Kuehne, 
• Chris Dickens, 
• David Tickner, 
• Mathis L. Messager, 
• Julian D. Olden, 
• Gordon O’Brien, 
• Bernhard Lehner, 
• Nishadi Eriyagama

• Published: September 13, 2023
• https://doi.org/10.1371/journal.pwat.0000101
• Peer Review
• Reader Comments

Rivers are the arteries of human civilisation and culture, providing essential goods and services that underpin water and food security, socio-economic development and climate resilience. They also support an extraordinary diversity of biological life. Human appropriation of land and water together with changes in climate have jointly driven rapid declines in river health and biodiversity worldwide, stimulating calls for an Emergency Recovery Plan for freshwater ecosystems. Yet freshwater ecosystems like rivers have been consistently under-represented within global agreements such as the UN Sustainable Development Goals and the UN Convention on Biological Diversity. Even where such agreements acknowledge that river health is important, implementation is hampered by inadequate global-scale indicators and a lack of coherent monitoring efforts. Consequently, there is no reliable basis for tracking global trends in river health, assessing the impacts of international agreements on river ecosystems and guiding global investments in river management to priority issues or regions. We reviewed national and regional approaches for river health monitoring to develop a comprehensive set of scalable indicators that can support “top-down” global surveillance while also facilitating standardised “bottom-up” local monitoring efforts. We evaluate readiness of these indicators for implementation at a global scale, based on their current status and emerging improvements in underlying data sources and methodologies. We chart a road map that identifies data and technical priorities and opportunities to advance global river health monitoring such that an adequate monitoring framework could be in place and implemented by 2030, with the potential for substantial enhancement by 2050. Lastly, we present recommendations for coordinated action and investment by policy makers, research funders and scientists to develop and implement the framework to support conservation and restoration of river health globally.

Citation: Kuehne LM, Dickens C, Tickner D, Messager ML, Olden JD, O’Brien G, et al. (2023) The future of global river health monitoring. PLOS Water 2(9): e0000101. https://doi.org/10.1371/journal.pwat.0000101

Editor: Jean-François Humbert, INRA/Sorbonne University, FRANCE

Received: February 19, 2023; Accepted: August 10, 2023; Published: September 13, 2023

Copyright: © 2023 Kuehne et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: No data is included in the paper.

Funding: This work was supported by the CGIAR Initiative on NEXUS Gains and the World Wildlife Fund (staff support of CD and NE; contracting of LMK), the Natural Sciences and Engineering Research Council of Canada (Vanier Canada Graduate Scholarship to MLM), the Université de Lyon (H2O’Lyon Doctoral Fellowship ANR-17-EUR-0018 to MLM) and the School of Aquatic and Fishery Sciences, University of Washington (Richard C. and Lois M. Worthington Endowment to JDO). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Nearly all aspects of human society are impacted by the health of rivers. Flowing waters act as centres of organisation within the landscape, offering countless cultural and ecological services, and supporting a rich diversity of plants and animals. However, rapid changes in water and land use, climate change and a host of other anthropogenic stressors threaten the biodiversity and ecological integrity of these ecosystems [ 1 ]. As long ago as 2005, the global Millennium Ecosystems Assessment [ 2 ] concluded that freshwater ecosystems were among the most degraded and being used unsustainably. Despite the prominence and persistence of challenges including water security and impacts of climate change on hydrology, attention to the conservation of freshwater ecosystems—including rivers—has nonetheless lagged at the global scale [ 3 ]. This may be due to the perception of freshwater systems as a resource for human use rather than a precious habitat [ 4 ], their more limited spatial extent that reduces public awareness [ 5 ], a historical lack of conservation champions [ 6 ], and inadequate transdisciplinary scholarship [ 7 ]. Additional hurdles are associated with understanding and managing rivers as complex networks [ 8 ], and longstanding traditions of large-scale regulation (i.e., dams, diversions) and water extraction. In response, recent years have witnessed mounting calls for global-scale research and policy actions to stem further losses and degradation of freshwater habitats [ 9 – 11 ].

A significant hurdle to addressing the freshwater biodiversity crisis is that the major global initiatives working to thrust ecosystems onto the global development agenda consistently lack robust representation of freshwater health. These initiatives include The Economics of Ecosystems and Biodiversity (TEEB) for water and wetlands [ 12 ], the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), Agenda 2030 on Sustainable Development (the SDGs), the post-2020 Kunming-Montreal global biodiversity framework (GBF) and the UN Decade on Ecosystem Restoration. All of these, together with globally impactful periodic reports such as the Ecological Footprint indicator [ 13 ], the Planetary Boundaries framework [ 14 ], the Water Footprint indicator [ 15 ], and others, lack comprehensive indicators of freshwater ecosystem health. Instead, these efforts generally rely on single or small numbers of proxies. For these reasons, the Emergency Recovery Plan for Freshwater Biodiversity [ 9 ], and subsequently the Sustainable Freshwater Transition set out by the UN Convention on Biological Diversity, called for the development of a more robust and inclusive suite of freshwater biodiversity and ecosystem health indicators. The aim of such indicators would be to provide a foundation for consistent, widespread monitoring as part of international environmental and sustainability agreements, whether focused on fresh waters generally or river health specifically.

This paper seeks to chart a path toward policy-relevant, global river health monitoring. Our approach synthesises and builds on the substantial work to monitor river health at national and regional scales over recent decades. Leveraging knowledge established through mature large-scale programs, we identify a robust framework of indicators that can be refined and improved over time through coordinated global policy, research, and data infrastructure developments (i.e., top-down efforts). This common framework can also support local, national, and regional efforts to monitor river health with protocols that are flexible but sufficiently standardised for results to be compared between contexts (i.e., bottom-up efforts). Our objective is to align diverse monitoring and research efforts toward strategic actions over the next two decades that will ultimately facilitate robust, comprehensive, and feasible reporting on global trends in river health.

Status of large-scale river health monitoring

The first step toward a global river health framework is to evaluate current policies, concepts, and data for monitoring and assessment of river health at large-scales (i.e., national to global). The most important development in the last century is undoubtedly the passage of national—or, in the case of the European Union, regional—laws and regulations that mandate restoration and maintenance of freshwater ecosystems to meet water quality or condition standards. Examples of such laws, most of which have been enacted in the last 50 years include the Clean Water Act (1972) in the USA, the Resource Management Act (1991) in New Zealand, the European Water Framework Directive (2000), the CONAMA—Conselho Nacional do Meio Ambiente 357/2005 in Brazil (2005) and the Water Act of South Africa (1998). These laws created legal and financial incentives within nations to develop and refine consistent monitoring and assessment methods over time ( Fig 1 ), including indicators and metrics to evaluate the status of river ecosystems [ 16 , 17 ]. Although mature, large-scale programs are mostly restricted to a handful of economically advantaged nations, they offer a critical foundation for international or intercontinental knowledge transfers to support monitoring of river health globally [ 18 ].

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

Years indicate the point at which the framework was initially published as peer-reviewed or grey literature; the subset of programs or approaches analysed herein are bolded.

https://doi.org/10.1371/journal.pwat.0000101.g001

The design of any monitoring program begins with the definition of ecosystem health. In this paper, we define ecosystem health as ’The ability of the aquatic ecosystem to support and maintain key ecological processes and a community of organisms with a species composition, diversity, and functional organisation as comparable as possible to that of undisturbed habitats within the region’ (Schofield & Davies, 1996 after Karr & Dudley, 1981). Assessments of river health can emphasise different types of indicators, which are often classified as driving forces, pressures, state, impact, and response (i.e., the DPSIR framework; [ 19 ]). Our definition of river health sets the stage for selecting indicators that reflect biophysical conditions, thus focusing on ecosystem state. This focus represents a strong departure from previous or ongoing evaluations of river health at global scales. Global assessments to date have instead concentrated on pressures on aquatic ecosystems, largely because of the relative ease of computing changes—actual or projected—in land use, anthropogenic impacts, and climate—based on remote sensing and modelled data. These pressure-based models have yielded estimates of water security and risk of biodiversity loss [ 20 ], human use of ecosystem services [ 21 ], and temporal and geographic changes in biodiversity [ 22 ].

The challenges, however, with such models are that pressures on aquatic ecosystems may or may not reflect ecosystem condition or state [ 23 , 24 ], and therefore can offer only limited insight into their relationship with driving forces and responses that can be adjusted through management, mitigation, or restoration [ 25 ]. Weak or unverifiable linkages between ecosystem state, pressures, and driving forces are unlikely to offer the strong justification needed to support policy changes or investments in river health [ 17 , 25 ]. Our focus on ecological state excludes human valuations of rivers, which may encompass socioeconomic, cultural, or spiritual values [ 26 ]. Although such valuations can and have been included in large-scale assessments of river health (e.g., [ 27 ]), we advance that the first priority is to address the considerable knowledge gaps and technical barriers to evaluating the biophysical state of rivers at a global scale. Our position is that there is an urgent need to develop a framework around ecosystem state, and forward the corresponding scientific and research agenda. Such a framework can then provide the foundation to subsequently incorporate relationships with responses and driving forces, as well as holistic social and human values.

The final critical component in designing a river health framework is the availability and quality of data to capture the chosen indicators. Data sources can be grouped into three, not necessarily mutually exclusive, classes: in situ monitoring data (including conventional biological sampling and in situ sensors as well as novel approaches of uncrewed vehicles, crowd-sourcing, or the analysis of environmental DNA), remote sensing imagery (including prospective satellite missions), and modelling (including predictive hydrological models, statistical models, or artificial intelligence and machine learning approaches). While data sources are generally expanding, fundamental challenges persist. The data required for multi-indicator monitoring frameworks are collected by myriad entities, many of which may not openly share data; datasets may also be scale-dependent, discontinuous, or come in incompatible formats (e.g. raster, vector, tables). A forward-thinking river health framework should, therefore, consider both current and anticipated data developments.

The quality of data available at varying scales is a foundational challenge. Bottom-up approaches to assess river health rely on collecting and compiling local information, often with high precision in situ data; yet this makes the expansion to larger regions time-consuming or even practically impossible. Indeed, given the paucity of river health monitoring in many parts of the world [ 18 ], monitoring global river health based on compilation of local information is a formidable task. However, top-down approaches, which usually rely on remote sensing or modelling, tend to use limited amounts of input data and are often coarse in their spatial or temporal resolution, rendering local interpretations inaccurate and uncertain.

To blend both bottom-up and top-down approaches in a global framework requires a scalable geospatial method that can discern local hydrographic features at high spatial resolution, while also allowing linkages to coarser global datasets or modelling results. A standardised, common geospatial framework based on pre-defined spatial units (e.g., river reaches and their catchments) can leverage the strengths of both approaches and adaptively incorporate higher-quality data over time. For example, results from top-down analyses can serve as initial placeholders until more precise local information (e.g., from national or regional monitoring programs) becomes available. These types of multi-scale hydrographic frameworks are increasingly available at full global coverage and high spatial resolution (e.g., HydroATLAS [ 28 ] MERIT Hydro-Vector [ 29 ]).

Besides scalability, a second foundational challenge in monitoring river health is the inherent topological structure of fluvial systems. In contrast to terrestrial systems, river health is determined by conditions in upstream drainage areas as well as more proximate influences. Point-based biological monitoring or instream water quality data can provide an integrated perspective (i.e., a healthy local habitat may indicate good conditions across the entire upstream catchment), and novel approaches such as eDNA analyses and improved chemical detectors offer promising avenues to scale up in situ sampling in the future [ 30 ]. But these methods are not yet available at a global scale, and may continue to require modelling support (e.g., for chemical compounds that are difficult to detect in the field) [ 1 ]. Using top-down approaches, upstream influences can be integrated through data processing and modelling that nests information within hierarchical catchments and allows routing of physical or biological properties along river networks (e.g., using accumulation and decay functions) (e.g., [ 24 ]). Of particular importance is the ability to evaluate longitudinal, lateral, vertical, and temporal connectivity, which is vital to freshwater ecosystems as it defines the fluxes, movement or dispersal of species, materials (including water and sediments), nutrients, and energy [ 31 ]. For this reason, a recommended framework should include a versatile geospatial data concept that can incorporate topological information of upstream, downstream and lateral connections as well as nested and hierarchical relationships between hydrographic features.

Review of monitoring approaches

We initiated this work by comprehensively reviewing existing programs and approaches to monitor and assess river health around the world [ 32 ]. We restricted our review to those implemented at a national, regional, or global scale, as we considered these most likely to possess the properties necessary to inform a global monitoring framework. We focused on operational programs that were developed for monitoring (i.e., surveillance) of river health, rather than investigative approaches. In addition to these, we also evaluated existing global indices of river health; although differing greatly from monitoring programs, their design and implementation offer important insights into the current state of global river health monitoring.

We compared each approach against the following seven criteria that are considered integral to a successful framework: consistency, representativeness, robustness, flexibility, scalability, feasibility, and informativeness [ 33 ]. To assess consistency, representativeness , and robustness , we evaluated methods of data collection and the number and types of indicators used. Flexibility, scalability , and feasibility were explored qualitatively, primarily based on the indicators and methods of data collection, followed by the complexity of methods used to harmonise and integrate data. Lastly, informativeness was qualitatively assessed in the conceptual design and methods that were used to frame and report results.

From this initial review, we identified 10 programs or approaches that met the majority of the seven criteria ( Fig 1 ). From each, we summarised the features or attributes that have the greatest potential to inform the design of a global framework: the indicators used in the assessment, the biophysical components that the indicators reflect, data types, methods of data harmonisation and integration, and practical insights applicable to the design of a global monitoring framework.

Development of the global monitoring framework

Based on the above review, we develop a framework of indicators for global river health monitoring, which we evaluated for feasibility of implementation at two time periods: by 2030 and by 2050. Rather than including indicators based on current feasibility, we considered all potential indicators, regardless of the state of readiness of the data sources or prognosis for development, even by 2050. For example, careful research and expert knowledge have gone into identifying Essential Biodiversity Variables [ 34 , 35 ], a suite of variables that are broadly agreed as necessary and sufficient to monitor national to global biodiversity. However, much coordinated and systematic development of data sources is still needed to characterise these variables at global scales [ 36 ]. Building on these and other studies that have evaluated and identified “ideal” indicators allows us to diagnose research and data gaps that, if addressed, could substantially advance monitoring of global river health. The 2030 and 2050 time horizons were chosen in light of technical considerations as well as the anticipated updating of global sustainability and ecological health initiatives (e.g., the SDGs which expire, but may be refreshed, in 2030). Given the time frames required for research and operationalizing new data sources and methods, the 2030 framework represents data sources and methods that are effectively available in the near term. The second time period of 2050 allows us to evaluate the technical horizon for promising yet feasible technologies, methods or infrastructure that can advance the accuracy and informativeness of these indicators in the near-to-medium future.

Because existing major river health monitoring programs stem from national or regional legislation, they vary in purpose (i.e., matched to specific regulatory context) and are influenced by the approaches and technologies in use at the time of their development ( Fig 1 ; Table 1 ).

Description and attributes of selected large-scale (i.e., national and regional) monitoring programs or global assessment methods determined as meeting a majority of seven criteria for a successful framework [ 33 ]. In any monitoring program, a conceptual framework designates relationships between Indicators, which are often grouped by broader biophysical Components (i.e., themes or categories). Further, the conceptual framework of a specific program may treat Components as driving forces (D), pressures (P), state (S), impact (I), or responses (R) (i.e., the DPSIR framework). [Note: Components and Indicators are presented using the terminology of the individual frameworks]. A majority of frameworks include procedures where indicator data are harmonised (i.e., standardised), integrated (i.e., combined) into Component scores, and assigned to condition classes for reporting the condition of the ecosystem.

https://doi.org/10.1371/journal.pwat.0000101.t001

Nearly two decades separate early, well-established frameworks [i.e, National Aquatic Resources Survey (NARS) and Water Framework Directive (WFD)] from later ones whose implementation is less well-documented [i.e., Freshwater Biophysical Ecosystem Health Framework (FBEHF) and River Health Index (RHI)]. More recent frameworks tend to include variables based on remote-sensing data, and more explicitly incorporate scale and catchment hierarchy into the conceptual designs and reporting of results [ 32 ]. Each of the large-scale river health programs has perceived advantages and disadvantages ( Table 1 ), and collectively they exemplify the key attributes a large-scale framework should possess. These include: a clear definition of ecosystem health; indicators of multiple biophysical components; standardised methods and protocols of data collection and integration; and scale independence ( Table 1 ). The main reasons for differences in the choice and treatment of components originate from the definition of “freshwater health”, which underlies the conceptual design that combines driving forces, pressures, state, impact and responses. For example, New Zealand’s FBEHF defines ecological integrity as the maintenance of structure and function “in the face of external stress”. Therefore, while the FBEHF relies on biophysical indicators to assess condition (i.e., state), it also recommends conceptual modelling of stressor pathways (i.e., pressures and driving forces) to guide management and policy actions for remediating indicators that are below targets [ 33 ].

The biophysical categories (hereafter, ‘components’) that are monitored, and the range and type of associated indicators differ greatly among river health monitoring frameworks. The four most commonly included components are 1) biology (aquatic life), 2) water quality (physicochemical conditions), 3) physical habitat, and 4) hydrology (water quantity & dynamics) ( Table 1 ), suggesting broad agreement that these components constitute a robust and comprehensive basis for river health monitoring. A majority of the national and regional programs concur in relying on the state of the biological indicators as the primary reflection of aquatic ecosystem or river health; greater differences occur in the treatment of abiotic indicators. Abiotic features may be considered primarily with respect to influencing the biological responses (e.g., NARS, National River Health Program) or incorporated as part of the definition and measurement of ecological health (e.g., WFD, RHI, FBEHF).

Limitations associated with the scale of the monitoring also drive some design decisions, such as availability of data that can reflect indicators of ecosystem health at large scales. This can be seen most starkly in the strong contrast between regional or national-scale monitoring programs and existing global frameworks. Global frameworks tend to emphasise pressures rather than ecosystem state ( Table 1 ) [ 32 ], reflecting current data constraints to assess river health at large scales. Regardless of the source and types of data that inform indicators, frameworks share similarities in the methods used to translate indicator data into an assessment of ecological condition. Large-scale frameworks consistently entail harmonisation (i.e., standardisation) of indicator data to a common scale (e.g., 0–100) against benchmark conditions; these may be relative to local, regional, or environmentally similar reference sites, based on the distribution of values, or predetermined targets. It is typical for assessments to integrate harmonised indicator scores to the level of components and/or to an overall score (though exceptions exist, e.g. NARS). Methods of integration range from simple or geometric averaging to expert ratings. Lastly, for reporting assessment results, integrated scores are commonly classified into 3–6 condition categories (e.g., NARS, RHI, WFD) or a condition gradient (e.g., River EcoStatus Monitoring Programme), although reporting may also include fixed thresholds (e.g., NARS) or proximity to goals (e.g., Environmental Performance Index).

Development of the global framework

Across the four biophysical components, we identified a comprehensive but parsimonious suite of indicators of river health, and provide a prognosis of their readiness at a global scale in 2030 and 2050 ( Table 2 ; S1 Table ). Since these indicators were selected to represent ecosystem state rather than driving forces, pressures, impacts, or responses, all data sources must ultimately be based on either direct measurements or estimation of biological, water quality, physical habitat, or hydrologic parameters ( S1 Table ). The exception is where an explicit decision is made to use proxies as an interim measure, due to data or modelling limitations. Direct measurement may be done via remote sensing or compilation of in situ data, while estimation involves modelling—including interpolation and/or fate-based modelling—that is calibrated with direct measurements.

Each indicator is described with both challenges and opportunities for application to global monitoring, the methods available for implementation by 2030, and recommendations for development toward more accurate and widespread implementation by 2050 [see S1 Table for sources of in situ , remote sensing, and modelled datasets to support development of specific indicators]. Inclusion of each indicator within national or regional and global monitoring programs is shown (● = included, × = not included).

https://doi.org/10.1371/journal.pwat.0000101.t002

The framework emphasises modelling approaches, which can produce spatially-explicit estimates of all indicators for all rivers. This stems from the fact that both in situ and remote sensing datasets have inherent (often differing) limitations in their utility to reflect the health of freshwater ecosystems at large scales. Modelling can incorporate multiple data sources for the calibration of indicators (or, potentially, interim use of pressure-based proxies), can yield predictions for smaller rivers which are often more data-limited, and offers a way to harmonise indicators into the same hydrographic structure and scale. Importantly, modelling allows representation of uncertainty, which can be reduced as better or more data are incorporated over time and also indicate priorities for improvement (e.g., by highlighting geographic disparities in in situ data).

We organise our presentation of the state-of the-art methods for river health monitoring by biophysical component, first evaluating indicators based on their current feasibility for implementation at a global scale (i.e., 2030) followed by recommendations for development over the next two decades (i.e., 2050).

We recommend five biological indicators of river health, which are fish abundance, fish diversity, invertebrate diversity, aquatic invasive species, and primary productivity. Because biological indicators integrate catchment conditions and anthropogenic influences, they are typically considered to best reflect the ecological state and health of riverine (and other aquatic) ecosystems [ 18 ]; it is not surprising that they are well represented in biological monitoring programs, even at large scales. However, the state of current data sources demonstrates consistent bottlenecks and limitations to implementation at global scales, which will require considerable investment and focus to overcome. For example, the IUCN Red List and the Living Planet Index, arguably the most developed and recognised global systems to assess conservation status of species, suffer from well-documented taxonomic and geographic bias [ 45 – 47 ].

The most obvious challenge for global monitoring of biological indicators is that remote sensing data offer little utility; the possible exception to this is primary productivity, for which chlorophyll can be used as a (limited) proxy [ 48 ]. Capacity to measure or model biological indicators is therefore dictated by the status and availability of global in situ datasets, which currently suffer from strong geographic limitations and bias ( S1 Table ). Given that widespread development of new large scale (i.e., regional or national) monitoring programs is not expected [ 18 ], developing untapped sources of in situ biological data are essential. The rapid development of eDNA in recent years offers particular promise to help overcome the lack of biological data, but will require investment toward application for specific indicators [ 49 ] and implementation at large-scales [ 50 ]. For example, although eDNA analyses of aquatic diversity is improving with community approaches such as universal markers or meta-barcoding—and with comparable or greater sensitivity than traditional methods [ 51 ]—considerable effort is yet needed to build reference sequences and the genetic databases that these approaches rely on [ 52 ]. For these reasons, the potential for other mechanisms to bolster global datasets of aquatic diversity should not be ignored, including processing of museum specimens [ 53 ], fostering citizen science observation networks and platforms [ 54 ], and collating data from national biomonitoring programs [ 24 ]. These options also require little technology, which may be of particular importance for broadening representation in geographically remote areas [ 55 , 56 ]. Model-based data integration methods also provide ways to leverage this growing quantity and types of biological data being collected [ 57 ].

Even anticipated development and expansion of in situ data from the above sources will likely contribute little to the improvement of two indicators, which are fish abundance and primary productivity. A primary drawback of eDNA metabarcoding to evaluate biodiversity is limited ability to infer abundance [ 58 ]. Citizen-science projects equally emphasise reporting species presence rather than abundance [ 56 ]. As such, the dominant sources of in situ data for these two indicators are most likely to come from ongoing compilation of data from disparate research and monitoring efforts, the most informative of which include multi-year time series for detection of trends [ 59 , 60 ]. However, it is not possible to recommend or rely on contributions by local or even national researchers and networks without acknowledging systemic and well-documented barriers to data sharing, ranging from lack of financial support for data synthesis to cultural perspectives [ 61 ]. Given the importance of in situ data to inform biological indicators for rivers (and other aquatic ecosystems), we recommend that research funders support the creation and expansion of large-scale datasets [ 62 ], as well as adopting data sharing criteria to promote behavioural and cultural shifts in scientific practice [ 63 ].

Water quality

Four water quality indicators are recommended to reflect ecological health of rivers: water temperature, nutrient concentrations, suspended sediments, and ecotoxicants ( Table 2 ). Despite current shortcomings, we find that several of these indicators are in a favourable position for implementation at a global scale in the near future. We attribute this readiness to the fact that the respective water quality constituents (temperature, nutrients, sediments) are closely tied to physical landscape features and catchment processes that can be modelled, and that are also more readily measured using remote sensing or in situ methods. Indicators of water quality are commonly included in large-scale monitoring programs ( Table 2 ), and compilation of in situ data that can support improvements in modelling is—albeit in early stages–underway in many places ( S1 Table ). Indeed, the priority opportunities for improvement that we foresee and recommend are in broadening the collection and global compilation of in situ data, including through citizen science monitoring [ 64 ], for improved calibration of existing physical models [ 65 , 66 ]. While satellite-based remote sensing of suspended sediments is already well-developed [ 67 , 68 ] and will continue to progress thanks to the increasing resolution of satellite-based optical imagery, the resolution of thermal infrared imagery is still relatively coarse (≥ 100-m pixel size) and can thus be applied to estimate temperature for only very large rivers at present. Nonetheless, higher resolution data afforded by the imminent launch of new sensors is expected to extend thermal remote sensing to smaller rivers and substantially improve the accuracy of global water temperature models [ 69 ].

Of the four recommended water quality indicators, ecotoxicants are currently the least feasible indicator for implementation in global river health monitoring. This is due to the fact that ecotoxicants are optically inactive and highly variable and localised in their release, concentrations and behaviour [ 70 , 71 ]. The diversity and sources of organic and synthetic chemicals that may be present in fresh waters is daunting. Although agricultural pesticides are often the dominant sources of chemical risk in freshwaters [ 72 , 73 ], other sources may range from heavy metal effluents from mining operations and urban land uses to endocrine-disrupting pharmaceuticals and engineered nanomaterials [ 1 , 74 ]. This heterogeneity makes it very difficult to monitor or model ecotoxicants at large scales based on relationships with catchment development or physical processes. We therefore recommend further exploration of pressure-based proxies for the near-term, and that new research advances our understanding and modelling of persistence, fate and ecotoxicology of chemicals in river ecosystems [ 71 ].

Physical habitat

Four indicators are recommended to reflect physical habitat quality of rivers: connectivity, channel feature diversity, riparian vegetation, and instream vegetation. As with water quality, we find that several of these indicators are relatively well-situated for implementation at a global scale in the near future. However, unlike with water quality, this readiness is not due to the existence of in situ datasets but rather that physical aspects of rivers are more easily characterised from remote sensing data. As a result, anticipated increases in the resolution and capacity of remote sensing products will substantially improve our ability to measure these indicators at a global scale ( S1 Table ). For example, recent launches of high-resolution global multispectral sensors have greatly advanced our ability to measure the extent and structure of riparian vegetation even for narrow riparian corridors, while hyperspectral sensors will increasingly enable species identification, to the extent of differentiating non-native species invasions or quantifying the prevalence of non-native species [ 75 ]. Launches of spaceborne LiDAR sensors will further improve this capacity [ 76 ], as well as the identification of channel feature diversity [ 77 ].

Metrics for assessing longitudinal connectivity (i.e., river fragmentation) at large scales are already well-developed [ 78 ]; however, the global datasets of river barriers that are needed to calculate these metrics are still highly incomplete [ 79 ]. Nonetheless, broader characterization of longitudinal barriers (i.e., beyond the current emphasis on relatively large dams, diversions and road crossings) is advancing with novel remote sensing techniques [ 80 , 81 ] and manual mapping [ 82 ], including citizen-science based efforts [ 83 ]. Lateral connectivity is an important aspect of physical habitat that has lagged substantially behind measurement of longitudinal connectivity, but is poised for substantial advancement at the global scale [e.g., 84 ]. Higher-resolution remote sensing products will allow identification of lateral barriers and lateral surface water coverage and dynamics [ 85 ], while automated and machine learning approaches (e.g., convolutional neural networks) are increasing the accuracy of surface water classifications, resulting in improved capacity to characterise lateral connectivity at large scales [ 86 , 87 ] and over time [ 88 ].

Although we predict consistent improvements in most physical habitat indicators based on higher resolution and better classification of remote sensing products, the exception to this trend is the characterization of instream vegetation, which is very challenging to assess remotely [ 89 ]. This is due to tradeoffs between spatial, temporal, spectral and radiometric resolution, all of which are needed for accurate estimation of aquatic vegetation. Aquatic plants are not routinely or comprehensively measured as part of large-scale monitoring programs, resulting in limited in situ datasets to support modelling and remote sensing classification training efforts. We recommend that developing this indicator will benefit most from modelling aquatic plant diversity and abundance based on hydrographic characteristics (e.g., discharge, floodplain extent, inundation) and nutrients [ 90 , 91 ], supported by the anticipated expansion of hyperspectral imagery [ 89 ]. It is also possible that environmental DNA (eDNA) sampling—if conducted at large scales–might inform measurement of aquatic plant diversity [ 92 ]. However, development of eDNA for aquatic plants is behind even other freshwater taxonomic groups [ 93 ]; and the relation of eDNA with abundance of plants (and other biological organisms) seems likely to remain elusive for some time.

Our recommended framework includes two hydrologic indicators of river health, which are the extent of surface water and the degree of alteration from the natural flow regime. Both of these indicators currently are in a state of moderate readiness for implementation at a global scale, mostly due to a bias toward measuring large rivers, resulting in limited and inconsistent data to monitor extent and flow of small or intermittent streams [ 94 ]. However, both indicators are likely to gain substantially from recent and anticipated improvements in remote sensing products ( S1 Table ). Measurements of flow alteration are commonly included in large-scale monitoring based on national gauge systems; however, these systems disproportionately monitor large, perennial, developed, and regulated rivers [ 95 ]. Global availability of discharge measurements also depends greatly on the financial and technical capacity of countries to collect data, combined with their willingness and capacity to provide access [ 96 , 97 ]. Despite ongoing calls and resolutions for international gauge data sharing, logistical, financial, and administrative constraints have caused gauge networks and data contributions to consistently decline for several decades [ 95 , 98 ]. Modelling of flow alteration at a global scale is plagued by both the limitations and availability of in situ data stated above, and challenges in downscaling models to reflect conditions in medium or small rivers [ 99 , 100 ]. Though likely to require several decades of development–we advance that one of the most promising opportunities to improve accuracy and resolution of discharge is the emerging use of satellite altimetry, which will help fill data gaps for large and medium rivers [ 101 ]. For small (and medium) rivers, another important opportunity lies in community science initiatives to monitor streamflow, which can range from maintaining and monitoring fixed gauges [ 102 , 103 ] to low-tech options for ungauged sites [ 104 ].

In contrast to streamflow, which has been routinely measured in some countries for more than a century, systematic mapping of surface water extent is only recently possible [ 105 ]; this indicator is therefore not well represented in large scale monitoring programs. Critical limitations in measurement of surface water at a global scale are the resolution of these remote sensing data, along with substantial challenges from overhanging and emergent vegetation and frozen, snow or glacial surfaces, which interfere with the optical properties of water [ 106 ]. For this reason, mapping of surface water extent for medium or small rivers has only become feasible with very recent launches of high-resolution sensors [ 85 ]. However, even these high-resolution products are unlikely to address the substantial issue of incorporating riverine wetland areas (i.e., riparian or forested), which may be permanently or seasonally inundated. Future development of this indicator that accounts for surface water across the full spectrum of riverine habitats will likely require a combined modelling approach based on classification of high-resolution remote sensing data and topographic analyses of wetland presence and extent [ 107 , 108 ].

We initiated this work in response to what is not only a dire situation for global river health monitoring, but where we believe the prognosis and trajectory for substantial improvement over time is currently uncertain. This position is supported by other strenuous calls for improvement in global monitoring and conservation of freshwater systems and biodiversity [ 9 , 11 , 36 , 109 ]. However, we advance that important developments in policy and research have also set the stage for adoption and step-wise implementation of a global river health monitoring framework, which can support adaptive management and restoration for rivers at diverse levels of geographic organization ( Fig 2 ).

Steps and associated benefits of implementing a river health framework that adaptively supports, coordinates, and integrates research and monitoring efforts from local to international scales. A common hydrographic framework provides the structure to integrate local monitoring (bottom-up) with regional or global data syntheses (top-down), and harmonise indicators across spatial scales. Degree of Health (represented by colours) based on indicators can be integrated at increasing scales, to inform prioritisation of investments for monitoring and restoration. [Note: Degree of Health shown in the figure is indicative only and does not represent quality for any region based on actual data]. Maps of the Nile Basin https://www.hydrosheds.org/products/hydrobasins [ 99 ] are reprinted with permission from the HydroBASINS Database, HydroSHEDS 2023. African continent https://hub.arcgis.com/datasets/africa::africa-countries/about [ 122 ] and world maps https://hub.arcgis.com/datasets/esri::world-countries-generalized/about [ 123 ] are reprinted with permission from Environmental Systems Research Institute, Inc., Esri Master License Agreement 7 Dec 2022.

https://doi.org/10.1371/journal.pwat.0000101.g002

A common framework to assess river health is a critical foundation to address global disparities in monitoring and evaluation. Regions and nations vary widely in the resources that they have available for this work, as well as the existence and structure of incentives [ 18 ]. An important outcome of a multi-scale framework is the ability to estimate river health in data-poor areas (albeit with more uncertainty), which can indicate geographic areas that should be prioritised for data collection, synthesis, and modelling [ 110 ]. As capacity grows to more accurately measure and compare the biophysical condition of rivers, at scales varying from reach to basin ( Fig 2 ), so too does the ability to relate condition to anthropogenic pressures and impacts, and to underlying socio-economic conditions and cultural values [ 34 ]. Biophysical conditions can serve as a basic template into which human perspectives and valuing of rivers are subsequently incorporated as additional indicators. These indicators can be developed at national or local scales, as appropriate, and with the involvement of diverse stakeholders [ 26 , 27 ].

A global framework will also help address disparities in river health monitoring by providing a structure for global coordination of research and monitoring efforts. Effective river health monitoring, protection, and restoration crosses standard jurisdictions, which is why there are many efforts at not only national but also basin, trans-boundary basin and regional scales [ 111 ]. A strong global commitment to a suite of river health indicators (i.e., our proposed framework) can guide and support existing and developing programs and provide structure to integrate monitoring efforts at diverse scales ( Fig 2 ) [ 35 ]. Such efforts may include the development of new monitoring tools, ranging from use of low-tech and/or citizen-science based gauging stations [e.g., CrowdHydrology, 104 ] to the development of new systems of governance or national monitoring programs [ 112 ]. A global framework can support and justify work by nations (or regions) that are engaged in or in a position to coordinate data gathering, synthesis, and evaluation toward a global agenda. Concurrently, international organisations and/or nations with resources can focus on the research gaps for global-scale indicators ( Table 2 )–many of which emphasise addressing data limitations in developing nations—when determining funding priorities.

Enabling factors

We see three fundamental factors needed to enable development and step-wise implementation of a global river health monitoring framework. First, we urge the adoption of river health monitoring and its benefits for sustainable water resource management as a priority within local, regional, and global initiatives (Steps 1–2, Fig 2 ). Rivers and river health warrant protection not only for the considerable ecological and social benefits they confer, but for the strong concordance and linkages with terrestrial conservation and protection efforts. Conservation planning has historically segregated terrestrial, marine, and freshwater ecosystems, and favoured terrestrial priorities and biodiversity, which can generally be protected in defined spatially restricted reserves [ 113 ]. However, there is mounting evidence for the co-benefits of integrating freshwater conservation and biodiversity targets into terrestrial conservation planning [ 114 , 115 ]. Specifically, because rivers are networks that connect habitats and integrate catchment conditions, actions that protect and restore rivers (and riparian areas) also benefit terrestrial ecosystems and biodiversity [ 116 , 117 ], and it has been found that freshwater targets can be dramatically improved with only negligible risk for terrestrial targets [ 114 , 118 ]. Regional and international agreements and conservation planning need to acknowledge and reflect the large contribution of rivers and river health to overall biodiversity.

Second, we recommend a resolute and coordinated focus to develop methods and synthesise data sources for the framework of indicators (Steps 3–4, Fig 2 ). Decades of large-scale monitoring programs support agreement on suitable indicators, and corresponding investment in their development for global scale implementation. This requires advancing data collection and synthesis for indicators, using methods that can range from incentivising individual scientists (and governments) to share local data, to improving the resolution and availability of remote sensing products [ 11 ]. The technologies that we have outlined could improve measurement of biophysical components (or specific indicators), but implementation at the global scale requires more than technical advancement. For example, eDNA–which can estimate aquatic species presence and/or abundance of some species–has the potential to dramatically improve the availability of in situ data for critically important biological indicators ( Table 2 ). However, its use for global river health monitoring requires that the technology is accessible and widely used (i.e., outside of developed countries), and that there are platforms to synthesise eDNA data, based on agreed-upon standards of detection [ 52 ]. Similarly, machine-learning approaches, including artificial intelligence to automate classification of remote sensing data, have strong potential to advance and refine the measurement of physical habitat and hydrologic indicators [ 86 , 88 ]. However, improving and implementing these approaches to assess river health requires interdisciplinary collaboration across fields of ecology, data science, and artificial intelligence.

As previously noted, a critical advancement toward global river monitoring is agreement on the use of a multi-scale framework [ 28 , 29 ] with standardised spatial units of river reaches and catchments (Step 5, Fig 2 ). A common hydrographic framework would provide the geospatial foundation for developing recommended procedures for data collection (e.g., determination of local or regional sampling sites, synthesis, modelling methods) as well as a system for harmonising indicator data to visualize and compare ecosystem condition ( Table 1 ). Together, a common spatial system and suite of indicators would allow individual governments and researchers working at local, national or regional scales to contribute environmental and monitoring data to the global framework (i.e., bottom-up). Concurrently, international organizations and researchers working at larger scales can focus efforts to develop and improve global data sources and methods to support and complement local and national efforts (i.e., top-down) (Steps 6–8, Fig 2 ).

This leads to our third recommendation, which is to identify and promote an international organisation responsible for the coordination of national or regional commitments and accountability. Simply stated, it is not possible for a national or even regional entity to coordinate the multi-scale efforts and diversity of actions needed, nor to sustain those efforts over the time scale that is required. We do not suggest that an international organisation would do all of the work, but would rather have accountability for finalising a framework, promoting and coordinating research activities (e.g., data synthesis, modelling), housing data repositories and products (or coordinating solutions), fostering grassroot developments, and encouraging relevant national and regional policy [e.g., 112 ]. An international organisation would also be well-positioned to lead or support efforts by member countries or other entities to fund work that advances the global research agenda. Depending on the scale of the work, funding could be sought from national funding agencies, large foundations, or global funding organisations (e.g., World Bank, Global Environment Facility).

Previous examples of an international effort that could be emulated is the Global Forest Resource Assessment Program (FRA), housed within the United Nations Food and Agriculture Organization. Initiated in 1946, the FRA has conducted global forest assessments in cooperation with member countries, which has included identification and promotion of a common framework of indicators [ 119 ]. The process has evolved and matured over time, integrating new monitoring technologies and incorporating bottom-up efforts from a larger number of nations and stakeholders as they have been developed and are available [ 120 , 121 ]. We recommend development of a similar initiative housed in an international program (e.g., the UN Environmental Programme, UN Food and Agriculture Organization) focused on river health monitoring. River health is inherently and inextricably intertwined with other environmental challenges that impact humans. An initiative to develop and improve a global river health framework would be well-positioned to work synergistically with other international initiatives, such as those focused on water security (e.g., the SDGs), biodiversity (e.g., IPBES, CBD), and climate change (e.g., the NDCs).

Applying the framework

The framework that we recommend is intended to support an adaptive process to monitor river health at a global scale. Importantly, we believe this process could result in an initial picture of global river health within the next 10 years, by 2030, a timeframe that is well-aligned to inform the anticipated review of international conventions (i.e., SDG and CBD). However, interim products could guide and inform current and emerging data monitoring, conservation, and restoration efforts. Monitoring that incorporates a majority of indicators could be implemented in data-rich areas to guide conservation and restoration planning at national or regional scales ( Fig 2 ); these would serve as useful test cases for iterative design of outputs and products (e.g., river health scorecards) that could effectively inform policy and public communications. Initial assessments at a global scale could be implemented using a subset of indicators for which data resources are robust and confidence is high ( Table 2 , Fig 2 ). Such initial or interim assessments could contribute data toward indicators and targets that are already outlined in international conventions, but which are currently inadequately measured. These include SDG 6.6.1 [“Change in the extent of water-related ecosystems over time”], IPBES [“Nature” or “Nature’s benefits to people”], multiple articles within RAMSAR [Articles 2.1–2.5, 3.2, 4.3, etc] and multiple targets within the Kunming-Montreal Global Biodiversity Framework [draft Targets 1,2,3,5 and 9].

Summary and conclusions

Historical challenges and technological barriers have stymied our capacity to monitor and assess the health of river ecosystems at a global scale. These include a relative lack of conservation awareness for fresh waters, a focus on the extractive rather than ecosystem value of rivers, monitoring methods developed for local and national purposes, and challenges in applying large-scale (i.e., remote sensing) monitoring methods to rivers. Decades of large-scale monitoring combined with technological advancements can now support development of a framework of indicators that represents the biophysical health of rivers at a global scale. However, widespread commitment to a framework is needed to focus and consolidate the monitoring approach, advance necessary research and data syntheses, and improve accuracy of these indicators over time. Through integration of bottom-up and top-down approaches, a consistent global framework will also provide critical support for river conservation and restoration efforts at scales ranging from local to international.

Supporting information

S1 table. data sources..

Current sources and compilations of in situ , remote sensing (RS), and modelled datasets that would support development of the recommended indicators outlined in Table 2 .

https://doi.org/10.1371/journal.pwat.0000101.s001

Acknowledgments

This work was carried out under the CGIAR Initiative on NEXUS Gains. We also gratefully acknowledge the logistical and administrative support of The International Water Management Institute.

• View Article
• PubMed/NCBI
• Google Scholar
• 2. Board MA. Millennium ecosystem assessment. Washington D.C.: New Island; 2005. https://www.millenniumassessment.org/en/index.html
• 12. Russi D, ten Brink P, Farmer A, Badura T, Coates D, Förster J, et al. The economics of ecosystems and biodiversity for water and wetlands. Ramsar Secretariat: Gland: IEEP: London and Brussels; 2013 p. 118p. https://teebweb.org/publications/water-wetlands/
• 13. Wackernagel M, Beyers B. Ecological footprint: Managing our biocapacity budget. New Society Publishers; 2019.
• 16. Hering D, Birk S, Solheim AL, Moe J, Carvalho L, Borja A, et al. Deliverable 2.2–2: Guidelines for indicator development. University of Duisburg-Essen: WISER (Water Bodies in Europe); 2010 p. 22. http://www.wiser.eu/download/D2.2-2.pdf
• 19. Stanners DA, Bourdeau P, European Environment Agency Task Force, United Nations, editors. Europe’s environment: the Dobříš assessment. Copenhagen: European Environment Agency; 1995.
• 32. Dickens J, Dickens C, Eriyagama N, Xie H, Tickner D. Towards a global river health assessment framework. Columbo, Sri Lanka: International Water Management Institute; 2022 p. 131 pp.
• 33. Clapcott J, Young R, Sinner J, Wilcox M, Storey R, Quinn J, et al. Freshwater biophysical ecosystem health framework. New Zealand: Ministry for the Environment; 2018 p. 104. Report No.: 3194. https://environment.govt.nz/publications/freshwater-biophysical-ecosystem-health-framework/
• 37. US EPA. National Rivers and streams assessment 2013–2014: A collaborative survey. Washington, DC: U.S. Environmental Protection Agency; 2020. Report No.: EPA 841-R-19-001. https://www.epa.gov/national-aquatic-resource-surveys/national-rivers-and-streams-assessment-2013-2014-results
• 38. Dallas H, Dickens C, Hill L, Kleynhans N, Louw D, Taylor J, et al. National Aquatic Ecosystem Health Monitoring Programme (NAEHMP): River Health Programme (RHP) Implementation Manual. Pretoria, South Africa: Department of Water Affairs and Forestry; 2008. Report No.: ISBN No. 978-0-621-383343-0. https://www.dws.gov.za/iwqs/rhp/projectdocuments/RHP_Implementation_Manual_FINAL_MAY2008_DWAF.pdf
• 39. Kleynhans CJ, Mackenzie J, Louw MD. Module F: Riparian vegetation response assessment index (VEGRAI). Pretoria, South Africa: Department of Water Affairs and Forestry; 2008 p. 98. http://www.dwa.gov.za/iwqs/rhp/eco/EcoStatus/ModuleF_VEGRAI/ModuleF_VEGRAI.pdf
• 41. Europai A, Tanasca U. Directive 2000/60/EC of the European parliament and of the Council of 23 October 2000 establishing establishing a framework for community action in the field of water policy. European Parliament, Council of the European Union; 2000. https://eur-lex.europa.eu/legal-content/en/ALL/?uri=CELEX%3A32000L0060
• 42. Department of the Environment and Energy. Module 5: Integrated ecosystem condition assessment. Canberra, Australia: Commonwealth of Australia; 2017. https://www.dcceew.gov.au/sites/default/files/documents/ae-toolkit-module-5-integrated-ecosystem-condition-assessment.pdf
• 43. Turak E, Waddell N, Johnstone G. New South Wales (NSW) Australian River Assessment System (AUSRIVAS) Sampling and Processing Manual. Sydney, Australia: Department of Environment and Conservation, New South Wales; 2004 p. 52. https://ausrivas.ewater.org.au/index.php/manuals-a-datasheets?id=55
• 44. Hsu A, Emerson J, Levy M, de Sherbinin A, Johnson L, Malik O, et al. The 2016 Environmental Performance Index Report. Yale Center for Environmental Law and Policy; 2016.
• 59. Deinet S, Scott-Gatty K, Rotton H, Twardek WM, Marconi V, McRae L, et al. The Living Planet Index (LPI) for migratory freshwater fish: Technical Report. Groningen: World Fish Migration Foundation; 2020 p. 31. https://worldfishmigrationfoundation.com/wp-content/uploads/2020/07/LPI_report_2020.pdf
• 69. Buffet L, Gamet P, Maisongrande P, Salcedo C, Crebassol P. The TIR instrument on TRISHNA satellite: a precursor of high resolution observation missions in the thermal infrared domain. In: Sodnik Z, Cugny B, Karafolas N, editors. International Conference on Space Optics—ICSO 2020. Online Only, France: SPIE; 2021. p. 26.
• 108. Halabisky M, Miller D, Stewart AJ, Lorigan D, Brasel T, Moskal LM. The Wetland Intrinsic Potential tool: Mapping wetland intrinsic potential through machine learning of multi-scale remote sensing proxies of wetland indicators. EGUsphere [preprint]. 2022; Preprint egusphere-2022-665.
• 122. ESRI. “Africa Countries” [Feature Layer]. Esri Africa; 2018. https://hub.arcgis.com/datasets/africa::africa-countries/about
• 123. ESRI. “World Countries Generalized” [Feature Layer]. Esri; 2022. https://hub.arcgis.com/datasets/esri::world-countries-generalized/about

Advertisement

Insight and Environment

Why rivers are important for everything from biodiversity to wellbeing.

The UK's 200,000 kilometres of waterway are in crisis. New Scientist's Save Britain's Rivers campaign reveals how crucial they are for the nation's health, wealth and resilience

By Graham Lawton

15 February 2023

The river Dee flows through England and Wales

Henry Ciechanowicz/Alamy

This article is part of  New Scientist and the  i’s  joint campaign, Save Britain’s Rivers .  The year-long collaboration will reveal what’s happening to the UK’s rivers and how to restore them through a series of special articles, films, podcasts and events.

STAND by a river in the UK and you are in touch with the ancients. Their short, gruff names – Thames, Leith, Taff, Lagan – speak volumes of the history of the islands, from ancient Britons through Romans, Saxons and Vikings. These rivers are part of the past and present. Yet they face an uncertain future.

All over the world, rivers are valuable, often sacred, cultural and practical assets. They are a defining feature of human settlements, exploited for millennia as a source of drinking water, food, irrigation, waste disposal, power, navigation, defence and even inspiration.

In the UK, many of these services are just as relevant today. Tap water comes mostly from rivers. Sewage is disposed into them – preferably treated but often not. Rivers irrigate crops, power homes, take away floodwaters and float boats. Millions of people spend some of their leisure time messing about on, or near, rivers.

The UK is a riverine country. Globally, about 0.8 per cent of the land is covered in freshwater. In the UK, that number is 3 per cent. It has about 1500 river systems , with a combined length of over 200,000 kilometres, ranging from gushing upland headwaters to languid floodplain meanderers, via a vast range of intermediate habitats.

By global standards, these rivers are short, narrow and shallow – “mere streams”, according to the National River Flow Archive at the UK Centre for Ecology & Hydrology in Wallingford. Yet they are extremely diverse in character. According to a recent report by the National Committee UK of the International Union for Conservation of Nature (IUCN), “rivers and their floodplains are among the most important environments in the UK”.

“It’s well known that rivers and their floodplains – and the two go hand in hand – support a disproportionate level of biodiversity relative to their size within landscapes,” says report co-author Stephen Addy at the James Hutton Institute in Aberdeen, UK.

The state of Britain's rivers: Slurry, silage and sewage

Drinking water and flood management

Although rivers are important for many reasons, their most obvious benefit in the UK is the water they supply. According to Water UK , which represents the country’s water industry, about two-thirds of tap water in England and Wales comes from rivers and the reservoirs and lakes they flow into; the rest is taken from aquifers. Northern Ireland and Scotland rely almost exclusively on rivers, reservoirs and lakes. All told, 87 per cent of the UK water supply comes from these sources.

According to government statistics , water companies in the UK abstract about 4.6 cubic kilometres of river, lake and reservoir water in England for the public supply every year. People drink it, bathe in it, flush their toilets with it, irrigate their gardens with it and use it to wash their clothes, floors and cars. Offices, shops, restaurants and other firms drink deep of it too.

Water is abstracted for other purposes. Electricity generators take 3.4 cubic kilometres to turn their steam turbines, while fish and watercress farms use 0.8 cubic kilometres and agriculture and private water supplies another 0.8. That adds up to a grand total of 9.6 cubic kilometres, equivalent to a cubic tank of water more than 2 kilometres in all dimensions.

Even in a relatively rainy country like the UK, that is milking it. The UK government estimates that about 1 in 5 surface water sources are depleted by over-abstraction , which has knock-on effects on river health.

The opposite problem – too much water – is an increasingly familiar hazard during the winter. Flooding is a growing problem as climate change causes extreme weather events, including biblical downpours. According to the Environment Agency, the UK has had six of its 10 wettest years on record since 1998 . Last year was the first to see three named Atlantic storms in the space of a week .

Natural floodplains can help to mitigate flood risk by corralling the excess water and releasing it slowly back into the river. That is especially true of riverine landscapes engineered by beavers, whose dams and pools massively slow the passage of water through the system. Where rain used to hit the ground and surge straight into the waterways, it now is trapped for weeks. Beavers are being reintroduced all over the UK after they gained legal protection last year .

Plastic waste dumped along the bank of the river Thames in London

Mark Phillips/Alamy

The problem is that many of those floodplains are far from natural, let alone beavered: housing estates and industrial development are often sited on them and these are generally quite useless at mitigating floods.

Water supplies and flood defences are two of many “ecosystem services” supplied by rivers. These are vital goods and services, such as water, pollination and clean air, that flow from nature, or what is increasingly referred to as natural capital.

Economic and health benefits

The UK was the first nation – and remains one of only 26 countries – to audit its natural capital. In 2012, the government established the (now disbanded) Natural Capital Committee (NCC) to advise it on the state of England’s natural capital, in order to help deliver its commitment “to be the first generation to leave the natural environment of England in a better state than it inherited”. In 2020, the NCC published its first set of accounts.

These are by no means complete, as the system for totting up natural capital, called experimental ecosystem accounting, remains a work in progress and nature is complex. But they still speak volumes about the value of rivers.

Water abstraction alone is worth £6.8 billion a year – essentially what it would cost to keep the taps on if rivers didn’t supply the UK with water – and the asset is worth £134 billion (the NCC stressed that these aren’t price tags on nature: given that the natural world supports all life on Earth, its value is infinite). Wetlands sequester 3.5 million tonnes of carbon a year, worth £831 million; that asset is valued at nearly £30 billion. Hydroelectricity generation produces 6865 gigawatt-hours a year, worth £136 million; the value of that asset is £2.2 billion.

These “provisioning and regulating” services are supplemented by some less tangible, but no less valuable cultural services. Around 1 in 10 of the UK’s 5.8 billion annual outdoor recreational and tourist visits are centred on freshwater, worth £681 million; the asset is worth £32 billion. Recreational fishing is a £1.7 billion a year industry. Around 2.7 million people gain health benefits from being in or around freshwater , worth £870 million a year. The asset value of this is nearly £48 billion. Even house prices benefit from the proximity of a river to the tune of £2.9 billion a year.

Essential habitats for biodiversity

One asset that has yet to be incorporated into natural capital accounting is biodiversity, but it is clear that rivers are an important repository of what is left in the UK. Globally, rivers and other bodies of fresh water are disproportionately biodiverse. Despite covering less than 1 per cent of Earth’s surface, they are home to around a third of described species of vertebrate , including approximately 40 per cent of all fish.

The UK’s rivers and the wetlands they feed are disproportionately biodiverse too, though to a lesser extent. They are home to around 10 per cent of the UK’s species , according to the Environment Agency. The IUCN lists 346 river-dependent species, some endangered, including eels, otters, the bar-tailed godwit and feather mosses. The Environment Agency says that over 10 per cent of UK freshwater and wetland species are threatened with extinction.

Rivers are biodiverse in part because they themselves are diverse. A short stretch of lowland river can feature 10 different habitats – pools, riffles (shallow water flowing quickly over stones), glides (deeper, slow-flowing water), backwaters, beds of aquatic vegetation, submerged tree roots, exposed sediment, riverbanks, riparian vegetation and floodplains – all of which provide food and shelter for a different repertoire of species. Further upstream are headwaters, waterfalls and rapids, which also host specialist species such as the freshwater pearl mussel, white-clawed crayfish, brook lamprey and bullhead, as well as juvenile salmon, trout and grey mullet. These juvenile fish will eventually migrate out to sea and become part of the UK fishing industry’s £713 million annual earnings .

Rare chalk streams and poor ecological health

England is also home to the vast majority of the world’s chalk streams, rare and internationally important habitats fed from alkaline aquifers in chalk and characterised by their gravel and flint beds and crystal clear water. They are home to unique ecosystems and have been described as an English Great Barrier Reef . There are only 210 of these waterways in the world and 170 of them are in England (the rest are in northern France).

Unsurprisingly, the value of ecosystem services is strongly related to the ecological state of the asset . In much of the UK, that isn’t a happy tale . England, Wales and Northern Ireland have no rivers considered to be in high ecological health, according to criteria laid down in the four nations’ Water Framework Directives ; only 14 per cent are good . The rest are moderate, poor or bad. None is in a good state in terms of chemical pollution and none is in good overall health. In Scotland, 8 per cent of rivers are in high ecological health.

The IUCN report is blunt on this issue, concluding that “truly natural [river] environments that have escaped both direct and indirect human alteration no longer exist”. However, there is hope, according to Addy. “There are some grounds for being optimistic. River restoration in the UK is undergoing a step change, there are more and more projects going on everywhere.”

• mental health /
• biodiversity /
• Save Britain's Rivers

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox! We'll also keep you up to date with New Scientist events and special offers.

More from New Scientist

Explore the latest news, articles and features

When nature gives people the 'ick'

Subscriber-only

The US is doing its biggest-ever survey of nature and wildlife

Why we need to be honest with children about the brutality of nature, environment, popular articles.

Trending New Scientist articles

• Reference Manager
• Simple TEXT file

People also looked at

Review article, effects of water pollution on human health and disease heterogeneity: a review.

• 1 Research Center for Economy of Upper Reaches of the Yangtse River/School of Economics, Chongqing Technology and Business University, Chongqing, China
• 2 School of Economics and Management, Huzhou University, Huzhou, China

Background: More than 80% of sewage generated by human activities is discharged into rivers and oceans without any treatment, which results in environmental pollution and more than 50 diseases. 80% of diseases and 50% of child deaths worldwide are related to poor water quality.

Methods: This paper selected 85 relevant papers finally based on the keywords of water pollution, water quality, health, cancer, and so on.

Results: The impact of water pollution on human health is significant, although there may be regional, age, gender, and other differences in degree. The most common disease caused by water pollution is diarrhea, which is mainly transmitted by enteroviruses in the aquatic environment.

Discussion: Governments should strengthen water intervention management and carry out intervention measures to improve water quality and reduce water pollution’s impact on human health.

Introduction

Water is an essential resource for human survival. According to the 2021 World Water Development Report released by UNESCO, the global use of freshwater has increased six-fold in the past 100 years and has been growing by about 1% per year since the 1980s. With the increase of water consumption, water quality is facing severe challenges. Industrialization, agricultural production, and urban life have resulted in the degradation and pollution of the environment, adversely affecting the water bodies (rivers and oceans) necessary for life, ultimately affecting human health and sustainable social development ( Xu et al., 2022a ). Globally, an estimated 80% of industrial and municipal wastewater is discharged into the environment without any prior treatment, with adverse effects on human health and ecosystems. This proportion is higher in the least developed countries, where sanitation and wastewater treatment facilities are severely lacking.

Sources of Water Pollution

Water pollution are mainly concentrated in industrialization, agricultural activities, natural factors, and insufficient water supply and sewage treatment facilities. First, industry is the main cause of water pollution, these industries include distillery industry, tannery industry, pulp and paper industry, textile industry, food industry, iron and steel industry, nuclear industry and so on. Various toxic chemicals, organic and inorganic substances, toxic solvents and volatile organic chemicals may be released in industrial production. If these wastes are released into aquatic ecosystems without adequate treatment, they will cause water pollution ( Chowdhary et al., 2020 ). Arsenic, cadmium, and chromium are vital pollutants discharged in wastewater, and the industrial sector is a significant contributor to harmful pollutants ( Chen et al., 2019 ). With the acceleration of urbanization, wastewater from industrial production has gradually increased. ( Wu et al., 2020 ). In addition, water pollution caused by industrialization is also greatly affected by foreign direct investment. Industrial water pollution in less developed countries is positively correlated with foreign direct investment ( Jorgenson, 2009 ). Second, water pollution is closely related to agriculture. Pesticides, nitrogen fertilizers and organic farm wastes from agriculture are significant causes of water pollution (RCEP, 1979). Agricultural activities will contaminate the water with nitrates, phosphorus, pesticides, soil sediments, salts and pathogens ( Parris, 2011 ). Furthermore, agriculture has severely damaged all freshwater systems in their pristine state ( Moss, 2008 ). Untreated or partially treated wastewater is widely used for irrigation in water-scarce regions of developing countries, including China and India, and the presence of pollutants in sewage poses risks to the environment and health. Taking China as an example, the imbalance in the quantity and quality of surface water resources has led to the long-term use of wastewater irrigation in some areas in developing countries to meet the water demand of agricultural production, resulting in serious agricultural land and food pollution, pesticide residues and heavy metal pollution threatening food safety and Human Health ( Lu et al., 2015 ). Pesticides have an adverse impact on health through drinking water. Comparing pesticide use with health life Expectancy Longitudinal Survey data, it was found that a 10% increase in pesticide use resulted in a 1% increase in the medical disability index over 65 years of age ( Lai, 2017 ). The case of the Musi River in India shows a higher incidence of morbidity in wastewater-irrigated villages than normal-water households. Third, water pollution is related to natural factors. Taking Child Loess Plateau as an example, the concentration of trace elements in water quality is higher than the average world level, and trace elements come from natural weathering and manufacture causes. Poor river water quality is associated with high sodium and salinity hazards ( Xiao et al., 2019 ). The most typical water pollution in the middle part of the loess Plateau is hexavalent chromium pollution, which is caused by the natural environment and human activities. Loess and mudstone are the main sources, and groundwater with high concentrations of hexavalent chromium is also an important factor in surface water pollution (He et al., 2020). Finally, water supply and sewage treatment facilities are also important factors affecting drinking water quality, especially in developing countries. In parallel with China rapid economic growth, industrialization and urbanization, underinvestment in basic water supply and treatment facilities has led to water pollution, increased incidence of infectious and parasitic diseases, and increased exposure to industrial chemicals, heavy metals and algal toxins ( Wu et al., 1999 ). An econometric model predicts the impact of water purification equipment on water quality and therefore human health. When the proportion of household water treated with water purification equipment is reduced from 100% to 90%, the expected health benefits are reduced by up to 96%.. When the risk of pretreatment water quality is high, the decline is even more significant ( Brown and Clasen, 2012 ).

To sum up, water pollution results from both human and natural factors. Various human activities will directly affect water quality, including urbanization, population growth, industrial production, climate change, and other factors ( Halder and Islam, 2015 ) and religious activities ( Dwivedi et al., 2018 ). Improper disposal of solid waste, sand, and gravel is also one reason for decreasing water quality ( Ustaoğlua et al., 2020 ).

Impact of Water Pollution on Human Health

Unsafe water has severe implications for human health. According to UNESCO 2021 World Water Development Report , about 829,000 people die each year from diarrhea caused by unsafe drinking water, sanitation, and hand hygiene, including nearly 300,000 children under the age of five, representing 5.3 percent of all deaths in this age group. Data from Palestine suggest that people who drink municipal water directly are more likely to suffer from diseases such as diarrhea than those who use desalinated and household-filtered drinking water ( Yassin et al., 2006 ). In a comparative study of tap water, purified water, and bottled water, tap water was an essential source of gastrointestinal disease ( Payment et al., 1997 ). Lack of water and sanitation services also increases the incidence of diseases such as cholera, trachoma, schistosomiasis, and helminthiasis. Data from studies in developing countries show a clear relationship between cholera and contaminated water, and household water treatment and storage can reduce cholera ( Gundry et al., 2004 ). In addition to disease, unsafe drinking water, and poor environmental hygiene can lead to gastrointestinal illness, inhibiting nutrient absorption and malnutrition. These effects are especially pronounced for children.

Purpose of This Paper

More than two million people worldwide die each year from diarrhoeal diseases, with poor sanitation and unsafe drinking water being the leading cause of nearly 90% of deaths and affecting children the most (United Nations, 2016). More than 50 kinds of diseases are caused by poor drinking water quality, and 80% of diseases and 50% of child deaths are related to poor drinking water quality in the world. However, water pollution causes diarrhea, skin diseases, malnutrition, and even cancer and other diseases related to water pollution. Therefore, it is necessary to study the impact of water pollution on human health, especially disease heterogeneity, and clarify the importance of clean drinking water, which has important theoretical and practical significance for realizing sustainable development goals. Unfortunately, although many kinds of literature focus on water pollution and a particular disease, there is still a lack of research results that systematically analyze the impact of water pollution on human health and the heterogeneity of diseases. Based on the above background and discussion, this paper focuses on the effect of water pollution on human health and its disease heterogeneity.

Materials and Methods

Search process.

This article uses keywords such as “water,” “water pollution,” “water quality,” “health,” “diarrhea,” “skin disease,” “cancer” and “children” to search Web of Science and Google Scholar include SCI and SSCI indexed papers, research reports, and works from 1990 to 2021.

Inclusion-Exclusion Criteria and Data Extraction Process

The existing literature shows that water pollution and human health are important research topics in health economics, and scholars have conducted in-depth research. As of 30 December 2021, 104 related literatures were searched, including research papers, reviews and conference papers. Then, according to the content relevancy, 19 papers were eliminated, and 85 papers remained. The purpose of this review is to summarize the impact of water pollution on human health and its disease heterogeneity and to explore how to improve human health by improving water pollution control measures.

Information extracted from all included papers included: author, publication date, sample country, study methodology, study purpose, and key findings. All analysis results will be analyzed according to the process in Figure 1 .

FIGURE 1 . Data extraction process (PRISMA).

The relevant information of the paper is exported to the Excel database through Endnote, and the duplicates are deleted. The results were initially extracted by one researcher and then cross-checked by another researcher to ensure that all data had been filtered and reviewed. If two researchers have different opinions, the two researchers will review together until a final agreement is reached.

Quality Assessment of the Literature

The JBI Critical Appraisal Checklist was used to evaluate the quality of each paper. The JBI (Joanna Briggs Institute) key assessment tool was developed by the JBI Scientific Committee after extensive peer review and is designed for system review. All features of the study that meet the following eight criteria are included in the final summary:1) clear purpose; 2) Complete information of sample variables; 3) Data basis; 4) the validity of data sorting; 5) ethical norms; (6); 7) Effective results; 8) Apply appropriate quantitative methods and state the results clearly. Method quality is evaluated by the Yes/No questions listed in the JBI Key Assessment List. Each analysis paper received 6 out of 8.

The quality of drinking water is an essential factor affecting human health. Poor drinking water quality has led to the occurrence of water-borne diseases. According to the World Health Organization (WHO) survey, 80% of the world’s diseases and 50% of the world’s child deaths are related to poor drinking water quality, and there are more than 50 diseases caused by poor drinking water quality. The quality of drinking water in developing countries is worrying. The negative health effects of water pollution remain the leading cause of morbidity and mortality in developing countries. Different from the existing literature review, this paper mainly studies the impact of water pollution on human health according to the heterogeneity of diseases. We focuses on diarrhea, skin diseases, cancer, child health, etc., and sorts out the main effects of water pollution on human health ( Table 1 ).

TABLE 1 . Major studies on the relationship between water pollution and health.

Water Pollution and Diarrhea

Diarrhea is a common symptom of gastrointestinal diseases and the most common disease caused by water pollution. Diarrhea is a leading cause of illness and death in young children in low-income countries. Diarrhoeal diseases account for 21% of annual deaths among children under 5 years of age in developing countries ( Waddington et al., 2009 ). Many infectious agents associated with diarrhea are directly related to contaminated water ( Ahmed and Ismail, 2018 ). Parasitic worms present in non-purifying drinking water when is consumed by human beings causes diseases ( Ansari and Akhmatov., 2020 ) . It was found that treated water from water treatment facilities was associated with a lower risk of diarrhea than untreated water for all ages ( Clasen et al., 2015 ). For example, in the southern region of Brazil, a study found that factors significantly associated with an increased risk of mortality from diarrhoea included lack of plumbed water, lack of flush toilets, poor housing conditions, and overcrowded households. Households without access to piped water had a 4.8 times higher risk of infant death from diarrhea than households with access to piped water ( Victora et al., 1988 )

Enteroviruses exist in the aquatic environment. More than 100 pathogenic viruses are excreted in human and animal excreta and spread in the environment through groundwater, estuarine water, seawater, rivers, sewage treatment plants, insufficiently treated water, drinking water, and private wells ( Fong and Lipp., 2005 ). A study in Pakistan showed that coliform contamination was found in some water sources. Improper disposal of sewage and solid waste, excessive use of pesticides and fertilizers, and deteriorating pipeline networks are the main causes of drinking water pollution. The main source of water-borne diseases such as gastroenteritis, dysentery, diarrhea, and viral hepatitis in this area is the water pollution of coliform bacteria ( Khan et al., 2013 ). Therefore, the most important role of water and sanitation health interventions is to hinder the transmission of diarrheal pathogens from the environment to humans ( Waddington et al., 2009 ).

Meta-analyses are the most commonly used method for water quality and diarrhea studies. It was found that improving water supply and sanitation reduced the overall incidence of diarrhea by 26%. Among Malaysian infants, having clean water and sanitation was associated with an 82% reduction in infant mortality, especially among infants who were not breastfed ( Esrey et al., 1991 ). All water quality and sanitation interventions significantly reduced the risk of diarrhoeal disease, and water quality interventions were found to be more effective than previously thought. Multiple interventions (including water, sanitation, and sanitation measures) were not more effective than single-focus interventions ( Fewtrell and Colford., 2005 ). Water quality interventions reduced the risk of diarrhoea in children and reduced the risk of E. coli contamination of stored water ( Arnold and Colford., 2007 ). Interventions to improve water quality are generally effective in preventing diarrhoea in children of all ages and under 5. However, some trials showed significant heterogeneity, which may be due to the research methods and their conditions ( Clasen et al., 2007 ).

Water Pollution and Skin Diseases

Contrary to common sense that swimming is good for health, studies as early as the 1950s found that the overall disease incidence in the swimming group was significantly higher than that in the non-swimming group. The survey shows that the incidence of the disease in people under the age of 10 is about 100% higher than that of people over 10 years old. Skin diseases account for a certain proportion ( Stevenson, 1953 ). A prospective epidemiological study of beach water pollution was conducted in Hong Kong in the summer of 1986–1987. The study found that swimmers on Hong Kong’s coastal beaches were more likely than non-swimmers to complain of systemic ailments such as skin and eyes. And swimming in more polluted beach waters has a much higher risk of contracting skin diseases and other diseases. Swimming-related disease symptom rates correlated with beach cleanliness ( Cheung et al., 1990 ).

A study of arsenic-affected villages in the southern Sindh province of Pakistan emphasized that skin diseases were caused by excessive water quality. By studying the relationship between excessive arsenic in drinking water caused by water pollution and skin diseases (mainly melanosis and keratosis), it was found that compared with people who consumed urban low-arsenic drinking water, the hair of people who consumed high-arsenic drinking water arsenic concentration increased significantly. The level of arsenic in drinking water directly affects the health of local residents, and skin disease is the most common clinical complication of arsenic poisoning. There is a correlation between arsenic concentrations in biological samples (hair and blood) from patients with skin diseases and intake of arsenic-contaminated drinking water ( Kazi et al., 2009 ). Another Bangladesh study showed that many people suffer from scabies due to river pollution ( Hanif et al., 2020 ). Not only that, but water pollution from industry can also cause skin cancer ( Arif et al., 2020 ).

Studies using meta-analysis have shown that exposure to polluted Marine recreational waters can have adverse consequences, including frequent skin discomfort (such as rash or itching). Skin diseases in swimmers may be caused by a variety of pathogenic microorganisms ( Yau et al., 2009 ). People (swimmers and non-swimmers) exposed to waters above threshold levels of bacteria had a higher relative risk of developing skin disease, and levels of bacteria in seawater were highly correlated with skin symptoms.

Studies have also suggested that swimmers are 3.5 times more likely to report skin diseases than non-swimmers. This difference may be a “risk perception bias” at work on swimmers, who are generally aware that such exposure may lead to health effects and are more likely to detect and report skin disorders. It is also possible that swimmers exaggerated their symptoms, reporting conditions that others would not classify as true skin disorders ( Fleisher and Kay. 2006 ).

Water Pollution and Cancer

According to WHO statistics, the number of cancer patients diagnosed in 2020 reached 19.3 million, while the number of deaths from cancer increased to 10 million. Currently, one-fifth of all global fevers will develop cancer during their lifetime. The types and amounts of carcinogens present in drinking water will vary depending on where they enter: contamination of the water source, water treatment processes, or when the water is delivered to users ( Morris, 1995 ).

From the perspective of water sources, arsenic, nitrate, chromium, etc. are highly associated with cancer. Ingestion of arsenic from drinking water can cause skin cancer and kidney and bladder cancer ( Marmot et al., 2007 ). The risk of cancer in the population from arsenic in the United States water supply may be comparable to the risk from tobacco smoke and radon in the home environment. However, individual susceptibility to the carcinogenic effects of arsenic varies ( Smith et al., 1992 ). A high association of arsenic in drinking water with lung cancer was demonstrated in a northern Chilean controlled study involving patients diagnosed with lung cancer and a frequency-matched hospital between 1994 and 1996. Studies have also shown a synergistic effect of smoking and arsenic intake in drinking water in causing lung cancer ( Ferreccio et al., 2000 ). Exposure to high arsenic levels in drinking water was also associated with the development of liver cancer, but this effect was not significant at exposure levels below 0.64 mg/L ( Lin et al., 2013 ).

Nitrates are a broader contaminant that is more closely associated with human cancers, especially colorectal cancer. A study in East Azerbaijan confirmed a significant association between colorectal cancer and nitrate in men, but not in women (Maleki et al., 2021). The carcinogenic risk of nitrates is concentration-dependent. The risk increases significantly when drinking water levels exceed 3.87 mg/L, well below the current drinking water standard of 50 mg/L. Drinking water with nitrate concentrations lower than current drinking water standards also increases the risk of colorectal cancer ( Schullehner et al., 2018 ).

Drinking water with high chromium content will bring high carcinogenicity caused by hexavalent chromium to residents. Drinking water intake of hexavalent chromium experiments showed that hexavalent chromium has the potential to cause human respiratory cancer. ( Zhitkovich, 2011 ). A case from Changhua County, Taiwan also showed that high levels of chromium pollution were associated with gastric cancer incidence ( Tseng et al., 2018 ).

There is a correlation between trihalomethane (THM) levels in drinking water and cancer mortality. Bladder and brain cancers in both men and women and non-Hodgkin’s lymphoma and kidney cancer in men were positively correlated with THM levels, and bladder cancer mortality had the strongest and most consistent association with THM exposure index ( Cantor et al., 1978 ).

From the perspective of water treatment process, carcinogens may be introduced during chlorine treatment, and drinking water is associated with all cancers, urinary cancers and gastrointestinal cancers ( Page et al., 1976 ). Chlorinated byproducts from the use of chlorine in water treatment are associated with an increased risk of bladder and rectal cancer, with perhaps 5,000 cases of bladder and 8,000 cases of rectal cancer occurring each year in the United States (Morris, 1995).

The impact of drinking water pollutants on cancer is complex. Epidemiological studies have shown that drinking water contaminants, such as chlorinated by-products, nitrates, arsenic, and radionuclides, are associated with cancer in humans ( Cantor, 1997 ). Pb, U, F- and no3- are the main groundwater pollutants and one of the potential causes of cancer ( Kaur et al., 2021 ). In addition, many other water pollutants are also considered carcinogenic, including herbicides and pesticides, and fertilizers that contain and release nitrates ( Marmot et al., 2007 ). A case from Hebei, China showed that the contamination of nitrogen compounds in well water was closely related to the use of nitrogen fertilizers in agriculture, and the levels of three nitrogen compounds in well water were significantly positively correlated with esophageal cancer mortality ( Zhang et al., 2003 ).

In addition, due to the time-lag effect, the impact of watershed water pollution on cancer is spatially heterogeneous. The mortality rate of esophageal cancer caused by water pollution is significantly higher downstream than in other regions due to the impact of historical water pollution ( Xu et al., 2019 ). A study based on changes in water quality in the watershed showed that a grade 6 deterioration in water quality resulted in a 9.3% increase in deaths from digestive cancer. ( Ebenstein, 2012 ).

Water Pollution and Child Health

Diarrhea is a common disease in children. Diarrhoeal diseases (including cholera) kill 1.8 million people each year, 90 per cent of them children under the age of five, mostly in developing countries. 88% of diarrhoeal diseases are caused by inadequate water supply, sanitation and hygiene (Team, 2004). A large proportion of these are caused by exposure to microbially infected water and food, and diarrhea in infants and young children can lead to malnutrition and reduced immune resistance, thereby increasing the likelihood of prolonged and recurrent diarrhea ( Marino, 2007 ). Pollution exposure experienced by children during critical periods of development is associated with height loss in adulthood ( Zaveri et al., 2020 ). Diseases directly related to water and sanitation, combined with malnutrition, also lead to other causes of death, such as measles and pneumonia. Child malnutrition and stunting due to inadequate water and sanitation will continue to affect more than one-third of children in the world ( Bartlett, 2003 ). A study from rural India showed that children living in households with tap water had significantly lower disease prevalence and duration ( Jalan and Ravallion, 2003 ).

In conclusion, water pollution is a significant cause of childhood diseases. Air, water, and soil pollution together killed 940,000 children worldwide in 2016, two-thirds of whom were under the age of 5, and the vast majority occurred in low- and middle-income countries ( Landrigan et al., 2018 ). The intensity of industrial organic water pollution is positively correlated with infant mortality and child mortality in less developed countries, and industrial water pollution is an important cause of infant and child mortality in less developed countries ( Jorgenson, 2009 ). In addition, arsenic in drinking water is a potential carcinogenic risk in children (García-Rico et al., 2018). Nitrate contamination in drinking water may cause goiter in children ( Vladeva et al.., 2000 ).

Discussions

This paper reviews the environmental science, health, and medical literature, with a particular focus on epidemiological studies linking water quality, water pollution, and human disease, as well as studies on water-related disease morbidity and mortality. At the same time, special attention is paid to publications from the United Nations and the World Health Organization on water and sanitation health research. The purpose of this paper is to clarify the relationship between water pollution and human health, including: The relationship between water pollution and diarrhea, the mechanism of action, and the research situation of meta-analysis; The relationship between water pollution and skin diseases, pathogenic factors, and meta-analysis research; The relationship between water pollution and cancer, carcinogenic factors, and types of cancer; The relationship between water pollution and Child health, and the major childhood diseases caused.

A study of more than 100 literatures found that although factors such as country, region, age, and gender may have different influences, in general, water pollution has a huge impact on human health. Water pollution is the cause of many human diseases, mainly diarrhoea, skin diseases, cancer and various childhood diseases. The impact of water pollution on different diseases is mainly reflected in the following aspects. Firstly, diarrhea is the most easily caused disease by water pollution, mainly transmitted by enterovirus existing in the aquatic environment. The transmission environment of enterovirus depends on includes groundwater, river, seawater, sewage, drinking water, etc. Therefore, it is necessary to prevent the transmission of enterovirus from the environment to people through drinking water intervention. Secondly, exposure to or use of heavily polluted water is associated with a risk of skin diseases. Excessive bacteria in seawater and heavy metals in drinking water are the main pathogenic factors of skin diseases. Thirdly, water pollution can pose health risks to humans through any of the three links: the source of water, the treatment of water, and the delivery of water. Arsenic, nitrate, chromium, and trihalomethane are major carcinogens in water sources. Carcinogens may be introduced during chlorine treatment from water treatment. The effects of drinking water pollution on cancer are complex, including chlorinated by-products, heavy metals, radionuclides, herbicides and pesticides left in water, etc., Finally, water pollution is an important cause of children’s diseases. Contact with microbiologically infected water can cause diarrhoeal disease in children. Malnutrition and weakened immunity from diarrhoeal diseases can lead to other diseases.

This study systematically analyzed the impact of water pollution on human health and the heterogeneity of diseases from the perspective of different diseases, focusing on a detailed review of the relationship, mechanism and influencing factors of water pollution and diseases. From the point of view of limitations, this paper mainly focuses on the research of environmental science and environmental management, and the research on pathology is less involved. Based on this, future research can strengthen research at medical and pathological levels.

In response to the above research conclusions, countries, especially developing countries, need to adopt corresponding water management policies to reduce the harm caused by water pollution to human health. Firstly, there is a focus on water quality at the point of use, with interventions to improve water quality, including chlorination and safe storage ( Gundry et al., 2004 ), and provision of treated and clean water ( Khan et al., 2013 ). Secondly, in order to reduce the impact of water pollution on skin diseases, countries should conduct epidemiological studies on their own in order to formulate health-friendly bathing water quality standards suitable for their specific conditions ( Cheung et al., 1990 ). Thirdly, in order to reduce the cancer caused by water pollution, the whole-process supervision of water quality should be strengthened, that is, the purity of water sources, the scientific nature of water treatment and the effectiveness of drinking water monitoring. Fourthly, each society should prevent and control source pollution from production, consumption, and transportation ( Landrigan et al., 2018 ). Fifthly, health education is widely carried out. Introduce environmental education, educate residents on sanitary water through newspapers, magazines, television, Internet and other media, and enhance public health awareness. Train farmers to avoid overuse of agricultural chemicals that contaminate drinking water.

Author Contributions

Conceptualization, XX|; methodology, LL; data curation, HY; writing and editing, LL; project administration, XX|.

This article is a phased achievement of The National Social Science Fund of China: Research on the blocking mechanism of the critical poor households returning to poverty due to illness, No: 20BJY057.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Afroz, R., Rahman, A., and Rahman, A. (2017). Health Impact of River Water Pollution in Malaysia. Int. J. Adv. Appl. Sci. 4 (5), 78–85. doi:10.21833/ijaas.2017.05.014

CrossRef Full Text | Google Scholar

Ahmed, S., and Ismail, S. (2018). Water Pollution and its Sources, Effects and Management: a Case Study of Delhi. Int. J. Curr. Adv. Res. 7 (2), 10436–10442. doi:10.24327/ijcar.2018.10442.1768

Ansari, Z. Z., and Akhmatov, S. V. (2020). Impacts of Water Pollution on Human Health: A Case Study of Delhi .

Google Scholar

Arif, A., Malik, M. F., Liaqat, S., Aslam, A., Mumtaz, K., and Afzal, A. (2020). 3. Water Pollution and Industries. Pure Appl. Biol. (PAB) 9 (4), 2214–2224. doi:10.19045/bspab.2020.90237

Arnold, B. F., and Colford, J. M. (2007). Treating Water with Chlorine at Point-Of-Use to Improve Water Quality and Reduce Child Diarrhea in Developing Countries: a Systematic Review and Meta-Analysis. Am. J. Trop. Med. Hyg. 76 (2), 354–364. doi:10.4269/ajtmh.2007.76.354

PubMed Abstract | CrossRef Full Text | Google Scholar

Bartlett, S. (2003). Water, Sanitation and Urban Children: the Need to Go beyond “Improved” Provision. Environ. Urbanization 15 (2), 57–70. doi:10.1177/095624780301500220

Bessong, P. O., Odiyo, J. O., Musekene, J. N., and Tessema, A. (2009). Spatial Distribution of Diarrhoea and Microbial Quality of Domestic Water during an Outbreak of Diarrhoea in the Tshikuwi Community in Venda, South Africa. J. Health Popul. Nutr. 27 (5), 652–659. doi:10.3329/jhpn.v27i5.3642

Boldo, E., MartÍN-Olmedo, P., Medina, S., Pirard, P., Mouly, D., and Beaudeau, P. (2006). Towards the Quantification of Health Impacts Caused by Drinking-Water Pollution in European Countries. Epidemiology 17 (6), S447. doi:10.1097/00001648-200611001-01198

Brown, J., and Clasen, T. (2012). High Adherence Is Necessary to Realize Health Gains from Water Quality Interventions. PLoS ONE 7 (5), e36735–9. doi:10.1371/journal.pone.0036735

Cantor, K. P., Hoover, R., Mason, T. J., and McCabe, L. J. (1978). Associations of Cancer Mortality with Halomethanes in Drinking Water. J. Natl. Cancer Inst. 61 (4), 979

PubMed Abstract | Google Scholar

Cantor, K. P. (1997). Drinking Water and Cancer. Cancer Causes Control CCC 8 (3), 292–308. doi:10.1023/a:1018444902486

Chen, B., Wang, M., Duan, M., Ma, X., Hong, J., Xie, F., et al. (2019). In Search of Key: Protecting Human Health and the Ecosystem from Water Pollution in China. J. Clean. Prod. 228, 101–111. doi:10.1016/j.jclepro.2019.04.228

Cheung, W. H. S., Chang, K. C. K., Hung, R. P. S., and Kleevens, J. W. L. (1990). Health Effects of Beach Water Pollution in Hong Kong. Epidemiol. Infect. 105 (1), 139–162. doi:10.1017/s0950268800047737

Cheung, W. H. S., Hung, R. P. S., Chang, K. C. K., and Kleevens, J. W. L. (1991). Epidemiological Study of Beach Water Pollution and Health-Related Bathing Water Standards in Hong Kong. Water Sci. Technol. 23 (1-3), 243–252. doi:10.2166/wst.1991.0422

Chowdhary, P., Bharagava, R. N., Mishra, S., and Khan, N. (2020). Role of Industries in Water Scarcity and its Adverse Effects on Environment and Human Health. Environ. Concerns Sustain. Dev. , 235–256. doi:10.1007/978-981-13-5889-0_12

Clasen, T. F., Alexander, K. T., Sinclair, D., Boisson, S., Peletz, R., Chang, H. H., et al. (2015). Interventions to Improve Water Quality for Preventing Diarrhoea. Cochrane Database Syst. Rev. 10, CD004794. doi:10.1002/14651858.CD004794.pub3

Clasen, T., Schmidt, W.-P., Rabie, T., Roberts, I., and Cairncross, S. (2007). Interventions to Improve Water Quality for Preventing Diarrhoea: Systematic Review and Meta-Analysis. Bmj 334 (7597), 782. doi:10.1136/bmj.39118.489931.be

Conroy, R. M., Elmore-Meegan, M., Joyce, T., McGuigan, K. G., and Barnes, J. (1996). Solar Disinfection of Drinking Water and Diarrhoea in Maasai Children: a Controlled Field Trial. Lancet 348 (9043), 1695–1697. doi:10.1016/s0140-6736(96)02309-4

Dasgupta, P. (2004). Valuing Health Damages from Water Pollution in Urban Delhi, India: a Health Production Function Approach. Envir. Dev. Econ. 9 (1), 83–106. doi:10.1017/s1355770x03001098

Dwivedi, S., Mishra, S., and Tripathi, R. D. (2018). Ganga Water Pollution: A Potential Health Threat to Inhabitants of Ganga Basin. Environ. Int. 117, 327–338. doi:10.1016/j.envint.2018.05.015

Ebenstein, A. (2012). The Consequences of Industrialization: Evidence from Water Pollution and Digestive Cancers in China. Rev. Econ. Statistics 94 (1), 186–201. doi:10.1162/rest_a_00150

El-Kowrany, S. I., El- Zamarany, E. A., El-Nouby, K. A., El-Mehy, D. A., Abo Ali, E. A., and Othman, A. A. (2016). Water Pollution in the Middle Nile Delta, Egypt: an Environmental Study. J. Adv. Res. 7 (5), 781–794. doi:10.1016/j.jare.2015.11.005

Enrique Biagini, R. (1975). Chronic Arsenic Water Pollution in the Republic of Argentina. Med. Cutan. Ibero Lat. Am. 3 (6), 423

Esrey, S. A., Potash, J. B., Roberts, L., and Shiff, C. (1991). Effects of Improved Water Supply and Sanitation on Ascariasis, Diarrhoea, Dracunculiasis, Hookworm Infection, Schistosomiasis, and Trachoma. Bull. World Health Organ 69 (5), 609

Ferreccio, C., González, C., Milosavjlevic, V., Marshall, G., Sancha, A. M., and Smith, A. H. (2000). Lung Cancer and Arsenic Concentrations in Drinking Water in Chile. Epidemiology 11 (6), 673–679. doi:10.1097/00001648-200011000-00010

Fewtrell, L., and Colford, J. M. (2005). Water, Sanitation and Hygiene in Developing Countries: Interventions and Diarrhoea-A Review. Water Sci. Technol. A J. Int. Assoc. Water Pollut. Res. 52 (8), 133–142. doi:10.2166/wst.2005.0244

Fitzgerald, E. F., Schell, L. M., Marshall, E. G., Carpenter, D. O., Suk, W. A., and Zejda, J. E. (1998). Environmental Pollution and Child Health in Central and Eastern Europe. Environ. Health Perspect. 106 (6), 307–311. doi:10.1289/ehp.98106307

Fleisher, J. M., and Kay, D. (2006). Risk Perception Bias, Self-Reporting of Illness, and the Validity of Reported Results in an Epidemiologic Study of Recreational Water Associated Illnesses. Mar. Pollut. Bull. 52 (3), 264–268. doi:10.1016/j.marpolbul.2005.08.019

Fong, T.-T., and Lipp, E. K. (2005). Enteric Viruses of Humans and Animals in Aquatic Environments: Health Risks, Detection, and Potential Water Quality Assessment Tools. Microbiol. Mol. Biol. Rev. 69 (2), 357–371. doi:10.1128/mmbr.69.2.357-371.2005

Froom, P. (2009). Water Pollution and Cancer in Israeli Navy Divers. Int. J. Occup. Environ. Health 15 (3), 326–328. doi:10.1179/oeh.2009.15.3.326

Gundry, S., Wright, J., and Conroy, R. (2004). A Systematic Review of the Health Outcomes Related to Household Water Quality in Developing Countries. J. water health 2 (1), 1–13. doi:10.2166/wh.2004.0001

Halder, J., Islam, N., and Islam, N. (2015). Water Pollution and its Impact on the Human Health. Eh 2 (1), 36–46. doi:10.15764/eh.2015.01005

Hanif, M., Miah, R., Islam, M., and Marzia, S. (2020). Impact of Kapotaksha River Water Pollution on Human Health and Environment. Prog. Agric. 31 (1), 1–9. doi:10.3329/pa.v31i1.48300

Haseena, M., Malik, M. F., Javed, A., Arshad, S., Asif, N., Zulfiqar, S., et al. (2017). Water Pollution and Human Health. Environ. Risk Assess. Remediat. 1 (3), 20. doi:10.4066/2529-8046.100020

Henry, F. J., Huttly, S. R. A., Patwary, Y., and Aziz, K. M. A. (1990). Environmental Sanitation, Food and Water Contamination and Diarrhoea in Rural Bangladesh. Epidemiol. Infect. 104 (2), 253–259. doi:10.1017/s0950268800059422

Jalan, J., and Ravallion, M. (2003). Does Piped Water Reduce Diarrhea for Children in Rural India? J. Econ. 112 (1), 153–173. doi:10.1016/s0304-4076(02)00158-6

Jensen, P. K., Jayasinghe, G., Hoek, W., Cairncross, S., and Dalsgaard, A. (2004). Is There an Association between Bacteriological Drinking Water Quality and Childhood Diarrhoea in Developing Countries? Trop. Med. Int. Health 9 (11), 1210–1215. doi:10.1111/j.1365-3156.2004.01329.x

Jorgenson, A. K. (2009). Foreign Direct Investment and the Environment, the Mitigating Influence of Institutional and Civil Society Factors, and Relationships between Industrial Pollution and Human Health. Organ. Environ. 22 (2), 135–157. doi:10.1177/1086026609338163

Kaur, G., Kumar, R., Mittal, S., Sahoo, P. K., and Vaid, U. (2021). Ground/drinking Water Contaminants and Cancer Incidence: A Case Study of Rural Areas of South West Punjab, India. Hum. Ecol. Risk Assess. Int. J. 27 (1), 205–226. doi:10.1080/10807039.2019.1705145

Kazi, T. G., Arain, M. B., Baig, J. A., Jamali, M. K., Afridi, H. I., Jalbani, N., et al. (2009). The Correlation of Arsenic Levels in Drinking Water with the Biological Samples of Skin Disorders. Sci. Total Environ. 407 (3), 1019–1026. doi:10.1016/j.scitotenv.2008.10.013

Khan, S., Shahnaz, M., Jehan, N., Rehman, S., Shah, M. T., and Din, I. (2013). Drinking Water Quality and Human Health Risk in Charsadda District, Pakistan. J. Clean. Prod. 60, 93–101. doi:10.1016/j.jclepro.2012.02.016

Kochhar, N., Gill, G. S., Tuli, N., Dadwal, V., and Balaram, V. (2007). Chemical Quality of Ground Water in Relation to Incidence of Cancer in Parts of SW Punjab, India. Asian J. Water, Environ. Pollut. 4 (2), 107 doi:10.1086/114154

Kumar, S., Meena, H. M., and Verma, K. (2017). Water Pollution in India: its Impact on the Human Health: Causes and Remedies. Int. J. Appl. Environ. Sci. 12 (2), 275

Lai, W. (2017). Pesticide Use and Health Outcomes: Evidence from Agricultural Water Pollution in China. J. Environ. Econ. Manag. 86, 93–120. doi:10.1016/j.jeem.2017.05.006

Landrigan, P. J., Fuller, R., Fisher, S., Suk, W. A., Sly, P., Chiles, T. C., et al. (2018). Pollution and Children's Health. Sci. Total Environ. 650 (Pt 2), 2389–2394. doi:10.1016/j.scitotenv.2018.09.375

Lin, H.-J., Sung, T.-I., Chen, C.-Y., and Guo, H.-R. (2013). Arsenic Levels in Drinking Water and Mortality of Liver Cancer in Taiwan. J. Hazard. Mater. 262, 1132–1138. doi:10.1016/j.jhazmat.2012.12.049

Lu, Y., Song, S., Wang, R., Liu, Z., Meng, J., Sweetman, A. J., et al. (2015). Impacts of Soil and Water Pollution on Food Safety and Health Risks in China. Environ. Int. 77, 5–15. doi:10.1016/j.envint.2014.12.010

Marino, D. D. (2007). Water and Food Safety in the Developing World: Global Implications for Health and Nutrition of Infants and Young Children. J. Am. Dietetic Assoc. 107 (11), 1930–1934. doi:10.1016/j.jada.2007.08.013

Marmot, M., Atinmo, T., Byers, T., Chen, J., and Zeisel, S. H. (2007). Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Nutr. Bull.

Marr, A., and Dasgupta, N. (2009). Industrial Water Pollution in Dhaka, Bangladesh: Strategies and Incentives for Pollution Control in Small and Medium Enterprises. Int. J. Interdiscip. Soc. Sci. Annu. Rev. 3 (11), 97–108. doi:10.18848/1833-1882/cgp/v03i11/52752

Morris, R. D. (1995). Drinking Water and Cancer. Environ. Health Perspect. 103, 225. doi:10.2307/3432315

Moss, B. (2008). Water Pollution by Agriculture. Phil. Trans. R. Soc. B 363 (1491), 659–666. doi:10.1098/rstb.2007.2176

Page, T., Harris, R. H., and Epstein, S. S. (1976). Drinking Water and Cancer Mortality in Louisiana. Science 193 (4247), 55–57. doi:10.1126/science.935854

Pandey, S. (2006). Water Pollution and Health. Kathmandu Univ. Med. J. (KUMJ) 4 (1), 128. doi:10.1016/j.crvi.2013.04.013

Parris, K. (2011). Impact of Agriculture on Water Pollution in OECD Countries: Recent Trends and Future Prospects. Int. J. Water Resour. Dev. 27 (1), 33–52. doi:10.1080/07900627.2010.531898

Payment, P., Siemiatycki, J., Richardson, L., Renaud, G., Franco, E., and Prevost, M. (1997). A Prospective Epidemiological Study of Gastrointestinal Health Effects Due to the Consumption of Drinking Water. Int. J. Environ. Health Res. 7 (1), 5–31. doi:10.1080/09603129773977

Rabbani, M., Chowdhury, M., and Khan, N. A. (2010). Impacts of Industrial Pollution on Human Health: Empirical Evidences from an Industrial Hotspot (Kaliakoir) in Bangladesh. Asian J. Water, Environ. Pollut. 7 (1), 27

Rajal, V. B., Cruz, C., and Last, J. A. (2010). Water Quality Issues and Infant Diarrhoea in a South American Province. Glob. Public Health 5 (4), 348–363. doi:10.1080/17441690802447267

Rampen, F. H. J., Nelemans, P. J., and Verbeek, A. L. (1992). Is Water Pollution a Cause of Cutaneous Melanoma? Epidemiology 3, 263–265. doi:10.1097/00001648-199205000-00013

Royal Commission for Environmental Pollution 1979 Seventh Report. Agriculture and Pollution . London, UK: H.M.S.O .

Rusiñol, M., Fernandez-Cassi, X., Timoneda, N., Carratalà, A., and Abril, J. F. (2015). Evidence of Viral Dissemination and Seasonality in a Mediterranean River Catchment: Implications for Water Pollution Management. J. Environ. Manag. 159, 58–67. doi:10.1016/j.jenvman.2015.05.019

Schullehner, J., Hansen, B., Thygesen, M., Pedersen, C. B., and Sigsgaard, T. (2018). Nitrate in Drinking Water and Colorectal Cancer Risk: A Nationwide Population-Based Cohort Study. Int. J. Cancer 143 (1), 73–79. doi:10.1002/ijc.31306

Schwarzenbach, R. P., Egli, T., Hofstetter, T. B., Von Gunten, U., and Wehrli, B. (2010). Global Water Pollution and Human Health. Annu. Rev. Environ. Resour. 35, 109–136. doi:10.1146/annurev-environ-100809-125342

Sliman, N. A. (1978). Outbreak of Guillain-Barre Syndrome Associated with Water Pollution. Bmj 1 (6115), 751–752. doi:10.1136/bmj.1.6115.751

Smith, A. H., Hopenhayn-Rich, C., Bates, M. N., Goeden, H. M., Hertz-Picciotto, I., Duggan, H. M., et al. (1992). Cancer Risks from Arsenic in Drinking Water. Environ. Health Perspect. 97, 259–267. doi:10.1289/ehp.9297259

Stephens, J. K. (2002). Deterioration of Stored Domestic Water Quality and Diarrhoea in Zenu . University of Ghana .

Stevenson, A. H. (1953). Studies of Bathing Water Quality and Health. Am. J. Public Health Nations Health 43 (5 Pt 1), 529–538. doi:10.2105/ajph.43.5_pt_1.529

Team, S. H. (2004). Water, Sanitation and Hygiene Links to Health: Facts and Figures . World Health Organization .

Tondel, M., Rahman, M., Magnuson, A., Chowdhury, I. A., Faruquee, M. H., and Ahmad, S. A. (1999). The Relationship of Arsenic Levels in Drinking Water and the Prevalence Rate of Skin Lesions in Bangladesh. Environ. health Perspect. 107 (9), 727–729. doi:10.1289/ehp.99107727

Tseng, C.-H., Lei, C., and Chen, Y.-C. (2018). Evaluating the Health Costs of Oral Hexavalent Chromium Exposure from Water Pollution: A Case Study in Taiwan. J. Clean. Prod. 172, 819–826. doi:10.1016/j.jclepro.2017.10.177

Ustaoğlu, F., Tepe, Y., Taş, B., and Pag, N. (2020). Assessment of Stream Quality and Health Risk in a Subtropical Turkey River System: A Combined Approach Using Statistical Analysis and Water Quality Index. Ecol. Indic. , 113. doi:10.1016/j.ecolind.2019.105815

Vartiainen, T., Pukkala, E., Rienoja, T., Strandman, T., and Kaksonen, K. (1993). Population Exposure to Tri- and Tetrachloroethene and Cancer Risk: Two Cases of Drinking Water Pollution. Chemosphere 27 (7), 1171–1181. doi:10.1016/0045-6535(93)90165-2

Victora, C. G., Smith, P. G., Vaughan, J. P., Nobre, L. C., Lombard, C., Teixeira, A. M. B., et al. (1988). Water Supply, Sanitation and Housing in Relation to the Risk of Infant Mortality from Diarrhoea. Int. J. Epidemiol. 17 (3), 651–654. doi:10.1093/ije/17.3.651

Vladeva, S., Gatseva, P., and Gopina, G. (2000). Comparative Analysis of Results from Studies of Goitre in Children from Bulgarian Villages with Nitrate Pollution of Drinking Water in 1995 and 1998. Cent. Eur. J. Public Health 8 (3), 179

Waddington, H., Snilstveit, B., White, H., and Fewtrell, L. (2009). Water, Sanitation and Hygiene Interventions to Combat Childhood Diarrhoea in Developing Countries . New Delhi India Global Development Network International Initiative for Impact Evaluation Aug .

Witkowski, K. M., and Johnson, N. E. (1992). Organic-solvent Water Pollution and Low Birth Weight in Michigan. Soc. Biol. 39 (1-2), 45–54. doi:10.1080/19485565.1992.9988803

Wu, C., Maurer, C., Wang, Y., Xue, S., and Davis, D. L. (1999). Water Pollution and Human Health in China. Environ. Health Perspect. 107 (4), 251–256. doi:10.1289/ehp.99107251

Wu, H., Gai, Z., Guo, Y., Li, Y., Hao, Y., and Lu, Z. N. (2020). Does Environmental Pollution Inhibit Urbanization in China? A New Perspective through Residents' Medical and Health Costs. Environ. Res. 182 (Mar.), 109128–109128.9. doi:10.1016/j.envres.2020.109128

Xiao, J., Wang, L., Deng, L., and Jin, Z. (2019). Characteristics, Sources, Water Quality and Health Risk Assessment of Trace Elements in River Water and Well Water in the Chinese Loess Plateau. Sci. Total Environ. 650 (Pt 2), 2004–2012. doi:10.1016/j.scitotenv.2018.09.322

Xu, C., Xing, D., Wang, J., and Xiao, G. (2019). The Lag Effect of Water Pollution on the Mortality Rate for Esophageal Cancer in a Rapidly Industrialized Region in China. Environ. Sci. Pollut. Res. 26 (32), 32852–32858. doi:10.1007/s11356-019-06408-z

Xu, X., Wang, Q., and Li, C. (2022b). The Impact of Dependency Burden on Urban Household Health Expenditure and its Regional Heterogeneity in China: Based on Quantile Regression Method. Front. Public Health 10, 876088. doi:10.3389/fpubh.2022.876088

Xu, X., Yang, H., and Li, C. (2022a). Theoretical Model and Actual Characteristics of Air Pollution Affecting Health Cost: A Review. Ijerph 19, 3532. doi:10.3390/ijerph19063532

Yassin, M. M., Amr, S. S. A., and Al-Najar, H. M. (2006). Assessment of Microbiological Water Quality and its Relation to Human Health in Gaza Governorate, Gaza Strip. Public Health 120 (12), 1177. doi:10.1016/j.puhe.2006.07.026

Yau, V., Wade, T. J., de Wilde, C. K., and Colford, J. M. (2009). Skin-related Symptoms Following Exposure to Recreational Water: a Systematic Review and Meta-Analysis. Water Expo. Health 1 (2), 79–103. doi:10.1007/s12403-009-0012-9

Zaveri, E. D., Russ, J. D., Desbureaux, S. G., Damania, R., Rodella, A. S., and Ribeiro Paiva De Souza, G. (20203). The Nitrogen Legacy: The Long-Term Effects of Water Pollution on Human Capital . World Bank Policy Research Working Paper .

Zhang, X.-L., Bing, Z., Xing, Z., Chen, Z.-F., Zhang, J.-Z., Liang, S.-Y., et al. (2003). Research and Control of Well Water Pollution in High Esophageal Cancer Areas. Wjg 9 (6), 1187–1190. doi:10.3748/wjg.v9.i6.1187

Zhitkovich, A. (2011). Chromium in Drinking Water: Sources, Metabolism, and Cancer Risks. Chem. Res. Toxicol. 24 (10), 1617–1629. doi:10.1021/tx200251t

Keywords: water pollution, human health, disease heterogeneity, water intervention, health cost

Citation: Lin L, Yang H and Xu X (2022) Effects of Water Pollution on Human Health and Disease Heterogeneity: A Review. Front. Environ. Sci. 10:880246. doi: 10.3389/fenvs.2022.880246

Received: 21 February 2022; Accepted: 09 June 2022; Published: 30 June 2022.

Reviewed by:

Copyright © 2022 Lin, Yang and Xu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Xiaocang Xu, [email protected]

This article is part of the Research Topic

Bioaerosol Emission Characteristics and the Epidemiological, Occupational, and Public Health Risk Assessment of Waste and Wastewater Management

Sign up to get the latest WWF news delivered straight to your inbox

Why are rivers so important?

On World Rivers Day, we celebrate the world’s precious waterways. But across the world, and closer to home, rivers are under threat. Why are rivers so important? And what are we doing to protect them? 

It goes without saying, but fresh, clean water is essential for humans and nature to survive. Rivers are precious sources of fresh drinking water for people across the world. And when rivers are so badly polluted by industry or unevenly distributed by poor water management practices, it can be a case of life-or-death. This unfortunately happens across the world.  

We’re working with HSBC in Kanpur, India, to help more than 30 factories involved in the production of leather reduce their water use and pollution, benefitting the environment, workers and the local community with access to clean flowing water.  

With AB InBev, the world’s leading brewer with brands such as Budweiser under its wing, we’re working with communities to develop new enterprises and encourage sustainable farming practices along the River Rwizi in Uganda, securing this valuable water source for people and nature.

Freshwater habitats account for some of the richest biodiversity in the world, and rivers are a vital, vibrant ecosystem for many species.  

But even in the UK, over three quarters of our rivers fail to meet required health standards and face multiple threats – putting an increasing pressure on the diverse wildlife that call our beautiful rivers home: from kingfishers to otters and brown trout.

People depend on rivers for their way of life and their livelihoods. From fishing to agriculture, the way we manage our waterways has a direct impact on people’s lives.  

For example, in the Yangtze River in China, the introduction of a dam unintentionally prevented carp from spawning downstream, where a commercial fishery was located. By working with HSBC and the state-owned TGD (Three Gorges Dam) company, we worked to change how the dam operated, so that it mimicked the natural flow of the river. This boosted the carp population and allowed people to continue living off the river, when previously their livelihoods were at stake.  

It was similar story in the Mekong river basin spanning Cambodia, Laos, Myanmar, Thailand, Vietnam and China’s Yunnan province, where a quarter of the world’s freshwater fish are caught. Overfishing has caused fish populations to plummet – bad news for the fish, and for the 60 million people in the region reliant on fish in their diets.  We provided support to local communities to manage conservation zones and prevent illegal fishing, and as a result local people have found it far easier to live sustainably off the river. 

Rivers are absolutely vital: for fresh drinking water, for people’s livelihoods and for nature. Unfortunately, they’re still threatened. We must commit to recovering freshwater biodiversity, restoring natural river flows and cleaning up polluted water for people and nature to thrive.  

To learn more about our work with rivers and freshwater, click  here . 

• Search Menu
• Browse content in Arts and Humanities
• Browse content in Architecture
• History of Architecture
• Browse content in Art
• History of Art
• Browse content in Classical Studies
• Classical Literature
• Religion in the Ancient World
• Browse content in History
• Colonialism and Imperialism
• Diplomatic History
• Environmental History
• Genocide and Ethnic Cleansing
• Historical Geography
• History by Period
• History of Agriculture
• History of Gender and Sexuality
• Industrial History
• Intellectual History
• International History
• Legal and Constitutional History
• Local and Family History
• Maritime History
• Military History
• Political History
• Regional and National History
• Revolutions and Rebellions
• Slavery and Abolition of Slavery
• Social and Cultural History
• Theory, Methods, and Historiography
• Urban History
• World History
• Linguistics
• Browse content in Literature
• Literary Studies (Romanticism)
• Literary Studies (American)
• Literary Studies (European)
• Literary Studies - World
• Literary Studies (1500 to 1800)
• Literary Studies (19th Century)
• Literary Studies (20th Century onwards)
• Literary Studies (British and Irish)
• Literary Studies (Early and Medieval)
• Literary Studies (Fiction, Novelists, and Prose Writers)
• Literary Studies (Plays and Playwrights)
• Literary Studies (Poetry and Poets)
• Literary Studies (Postcolonial Literature)
• Literary Studies (Queer Studies)
• Literary Studies (War Literature)
• Literary Studies (Women's Writing)
• Literary Theory and Cultural Studies
• Shakespeare Studies and Criticism
• Media Studies
• Browse content in Music
• Applied Music
• Ethnomusicology
• Music Cultures
• Music and Media
• Music Theory and Analysis
• Musical Scores, Lyrics, and Libretti
• Musical Structures, Styles, and Techniques
• Musicology and Music History
• Performance Practice and Studies
• Race and Ethnicity in Music
• Browse content in Performing Arts
• Browse content in Philosophy
• Aesthetics and Philosophy of Art
• Epistemology
• History of Western Philosophy
• Metaphysics
• Moral Philosophy
• Philosophy of Language
• Philosophy of Mind
• Philosophy of Law
• Philosophy of Religion
• Philosophy of Science
• Philosophy of Mathematics and Logic
• Social and Political Philosophy
• Browse content in Religion
• Biblical Studies
• Christianity
• History of Religion
• Judaism and Jewish Studies
• Qumran Studies
• Religion and Politics
• Religion and Art, Literature, and Music
• Religious Studies
• Browse content in Society and Culture
• Cultural Studies
• Technology and Society
• Browse content in Law
• Company and Commercial Law
• Browse content in Comparative Law
• Systems of Law
• Browse content in Constitutional and Administrative Law
• Government Powers
• Local Government Law
• Criminal Law
• Employment and Labour Law
• Environment and Energy Law
• History of Law
• Human Rights and Immigration
• Intellectual Property Law
• Browse content in International Law
• Public International Law
• Jurisprudence and Philosophy of Law
• Law and Society
• Law and Politics
• Browse content in Legal System and Practice
• Legal Skills and Practice
• Medical and Healthcare Law
• Browse content in Policing
• Police Regional Planning
• Property Law
• Browse content in Medicine and Health
• History of Medicine
• Browse content in Public Health and Epidemiology
• Public Health
• Browse content in Science and Mathematics
• Browse content in Biological Sciences
• Microbiology
• Zoology and Animal Sciences
• Browse content in Earth Sciences and Geography
• Palaeontology
• Environmental Science
• History of Science and Technology
• Browse content in Psychology
• Clinical Psychology
• Cognitive Psychology
• Developmental Psychology
• Evolutionary Psychology
• Health Psychology
• Social Psychology
• Browse content in Social Sciences
• Browse content in Anthropology
• Theory and Practice of Anthropology
• Browse content in Business and Management
• Business Ethics
• Business History
• Corporate Social Responsibility
• Criminology and Criminal Justice
• Browse content in Economics
• Agricultural, Environmental, and Natural Resource Economics
• Econometrics and Mathematical Economics
• Economic History
• Economic Systems
• Economic Development and Growth
• Financial Markets
• History of Economic Thought
• International Economics
• Labour and Demographic Economics
• Macroeconomics and Monetary Economics
• Microeconomics
• Public Economics
• Urban, Rural, and Regional Economics
• Browse content in Environment
• Climate Change
• Conservation of the Environment (Social Science)
• Social Impact of Environmental Issues (Social Science)
• Browse content in Politics
• African Politics
• Comparative Politics
• Conflict Politics
• Environmental Politics
• International Relations
• Middle Eastern Politics
• Political Economy
• Political Theory
• Politics and Law
• Public Policy
• Russian Politics
• UK Politics
• US Politics
• Browse content in Regional and Area Studies
• African Studies
• Asian Studies
• Native American Studies
• Browse content in Sociology
• Childhood Studies
• Economic Sociology
• Health, Illness, and Medicine
• Migration Studies
• Organizations
• Race and Ethnicity
• Social Theory
• Social Stratification, Inequality, and Mobility
• Sociology of Religion
• Sociology of Education
• Urban and Rural Studies
• Reviews and Awards
• Journals on Oxford Academic
• Books on Oxford Academic

• < Previous
• Next chapter >

1 Why Should We Care About Rivers?

• Published: November 2004
• Cite Icon Cite
• Permissions Icon Permissions

This chapter focuses on the importance of rivers, and explains why humans should care about them. Rivers provide water to drink, water that helps crops to grow, and the water that fuels or cools industries. Water is a universal solvent and is used at some stage in the manufacture of every product that people consume. Rivers transport wastes, and to some extent transform them. If not for this self-purifying function of rivers, many estuaries and deltas would be even more polluted. Rivers transport goods, generate power, and sustain recreation. The chapter emphasizes that the society which does not protect its rivers destroys its own lifelines. It also reveals that despite the history of public awareness of environmental issues in America, many people remain unaware of how substantially human activities have altered rivers across the nation.

Signed in as

Institutional accounts.

• GoogleCrawler [DO NOT DELETE]
• Google Scholar Indexing

Personal account

• Sign in with email/username & password
• Get email alerts
• Save searches
• Purchase content
• Activate your purchase/trial code
• Add your ORCID iD

Institutional access

Sign in with a library card.

• Sign in with username/password
• Recommend to your librarian
• Institutional account management
• Get help with access

Access to content on Oxford Academic is often provided through institutional subscriptions and purchases. If you are a member of an institution with an active account, you may be able to access content in one of the following ways:

IP based access

Typically, access is provided across an institutional network to a range of IP addresses. This authentication occurs automatically, and it is not possible to sign out of an IP authenticated account.

Sign in through your institution

Choose this option to get remote access when outside your institution. Shibboleth/Open Athens technology is used to provide single sign-on between your institution’s website and Oxford Academic.

• Click Sign in through your institution.
• Select your institution from the list provided, which will take you to your institution's website to sign in.
• When on the institution site, please use the credentials provided by your institution. Do not use an Oxford Academic personal account.
• Following successful sign in, you will be returned to Oxford Academic.

If your institution is not listed or you cannot sign in to your institution’s website, please contact your librarian or administrator.

Enter your library card number to sign in. If you cannot sign in, please contact your librarian.

Society Members

Society member access to a journal is achieved in one of the following ways:

Sign in through society site

Many societies offer single sign-on between the society website and Oxford Academic. If you see ‘Sign in through society site’ in the sign in pane within a journal:

• Click Sign in through society site.
• When on the society site, please use the credentials provided by that society. Do not use an Oxford Academic personal account.

If you do not have a society account or have forgotten your username or password, please contact your society.

Sign in using a personal account

Some societies use Oxford Academic personal accounts to provide access to their members. See below.

A personal account can be used to get email alerts, save searches, purchase content, and activate subscriptions.

Some societies use Oxford Academic personal accounts to provide access to their members.

Viewing your signed in accounts

Click the account icon in the top right to:

• View your signed in personal account and access account management features.
• View the institutional accounts that are providing access.

Signed in but can't access content

Oxford Academic is home to a wide variety of products. The institutional subscription may not cover the content that you are trying to access. If you believe you should have access to that content, please contact your librarian.

For librarians and administrators, your personal account also provides access to institutional account management. Here you will find options to view and activate subscriptions, manage institutional settings and access options, access usage statistics, and more.

Our books are available by subscription or purchase to libraries and institutions.

• About Oxford Academic
• Publish journals with us
• University press partners
• What we publish
• New features  
• Open access
• Rights and permissions
• Accessibility
• Advertising
• Media enquiries
• Oxford University Press
• Oxford Languages
• University of Oxford

Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide

• Copyright © 2024 Oxford University Press
• Cookie settings
• Cookie policy
• Privacy policy
• Legal notice

This Feature Is Available To Subscribers Only

Sign In or Create an Account

This PDF is available to Subscribers Only

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

• Show search

Climate Change Stories

Water Connects Us All—Fish Included

The connection between fish and people.

February 26, 2024 | Last updated May 16, 2024

• What's at Stake
• Our Approaches
• Project Examples
• Critical Funding

Each year, more than 1,000 fish species around the world migrate to, from or within rivers to reproduce, escape predation or drought, find feeding grounds, seek warmer or cooler waters, or fulfill other critical life cycle needs. Healthy river and stream corridors are also essential for amphibians, reptiles and mammals, such as manatees and river porpoises. Some swim from larger rivers, lakes or headwaters, while others—like salmon, river herring and some trout—travel thousands of miles across oceans and bays to reach critical freshwater habitats. Sadly, their journeys are increasingly becoming more treacherous, or not possible at all.

World Fish Migration Day

May 25, 2024 will mark the 6th World Fish Migration Day (WFMD), a biennial event The Nature Conservancy helped found in 2014. WFMD is a global celebration to create awareness about the importance of migratory fish and free-flowing rivers. The WFMD website includes a list of scheduled events.

These aquatic species face obstacles of all sorts, such as dams, locks, levees and culverts, many of which are impassible. Sometimes the places they need to get to—floodplains, wetlands and side channels that offer life-stage-specific nutrition, protection from predators and ideal conditions for rearing young or laying eggs—have been destroyed or are severely degraded. We know that wetlands are disappearing at three times the rate of tropical forests, and, according to new research in Scientific Data , in just the last 30 years, we've lost nearly 232,000 square miles (600,000 square kilometers) of floodplains—an area the size of France or California.

And the same waters through which fish migrate or go to spawn are becoming increasingly polluted, or in some cases, drying up all together.

These are the primary reasons why freshwater species populations around the globe have declined an average of 81% since 1970—far more than declines seen in terrestrial or marine species.

Migratory Fish and Barriers by the Numbers

Monitored populations of migratory freshwater fish have declined an average of 81% between 1970 and 2020.

Just one-third of the world's longest rivers remain free-flowing.

River systems altered by dams and other barriers have led to 40% of America’s fish species being listed as imperiled and many commercial fisheries being decimated.

Nearly 1 million dams, culverts and other barriers across the United States block fish from migrating upstream.

Such declines affect more than just fish and other wildlife. Migratory fish support commercial and recreational fishing industries that generate tens of billions in revenue each year. In Alaska’s Bristol Bay alone, the sustainable commercial harvest of wild salmon is valued at $2.2 billion annually and employs more than 10,000 people. In 2022, Bristol Bay experienced a record return of nearly 72 million sockeye salmon. This yearly migration makes for a rich ecosystem and remarkable way of life for people in Indigenous communities where the harvest of wild salmon is a cherished part of their culture.

How We Improve Freshwater Health & Connectivity

We protect and restore freshwater systems.

Fresh water is connected to everything The Nature Conservancy does, and we’re determined to protect and restore freshwater ecosystems at unprecedented scales. By leveraging our long history of innovation and collaboration, we know we can scale up breakthrough strategies for fresh water that are durable and long-lasting. Our work in Ecuador serves as a prime example of ways in which we’re implementing long-term protection efforts to conserve freshwater systems above and below ground to keep them healthy and intact.

We’re already working on close to 400 projects in nearly 40 countries, but we must go further and faster to achieve our goals for 2030 . ( For a broader picture of our freshwater work around the globe, visit “ Water Connects Us All ” on nature.org .)

Protection and restoration can go hand-in-hand. TNC’s work to restore streams, rivers, wetlands and floodplains is a strategy we use to mitigate the impacts of man-made structures or development that affect the hydrology and health of freshwater systems and the wildlife and people that depend on them.

Many of these man-made structures, like ditches, levees or dikes, are designed to drain wetlands or straighten rivers by cutting them off from side channels or floodplains, which often provide some of the most important habitat for fish and a wide array of other species. These same structures can drastically impact the trees and plants in these places, which are adapted to periodic, natural fluctuations of high and low flows.

TNC has dozens of projects to improve the health of streams by restoring natural meanders and/or reconnecting them to side channels or other low-lying areas, and we and our partners have spearheaded some of the largest floodplain reconnection projects in the United States. Learn more .

We Overcome Barriers and Ensure Rivers Flow Freely

Only some one-third of the world’s largest rivers remain free flowing. Most have been severed by dams or other barriers. For example, in the United States, only some 2% of the nation’s 3 million miles of rivers and streams remain free-flowing and undeveloped, similar to other heavily developed nations. And countless other, smaller rivers and streams been altered by dams, locks, levees or culverts that impair or prevent the migration of aquatic species.

Overcoming Barriers

Below is a snapshot of how TNC addresses barriers that affect our freshwater systems. Click on each square to learn more.

Removing Obsolete Dams

In cases where the value dams provide is outweighed by operational costs and the impacts to nature and people, TNC supports their removal. The removal of dams restores flows and the benefits they provide to people and nature. Obsolete dams can have a wide range of impacts on the environment and local communities, including loss of biodiversity, blocking fish migrations, trapping sediment and nutrients that maintain habitat and estuary health, and altering flow patterns that drive the productivity of downstream floodplains and wetlands. These impacts can affect public safety, food and water supplies, livelihoods, recreation and overall community well-being.

Avoiding New Dams

Or ensuring the “right fit.” More than 161,000 miles (260,000 kilometers) of free-flowing rivers are at risk of being impacted by the construction of new hydropower dams—equal to more than 39 times the length of the Nile. The impacts of these new dams would fall disproportionately in river basins with the greatest freshwater fish harvests and with the highest diversity of freshwater species, and—in many cases—greatly affect critical food sources for or displace Indigenous peoples.

Although dams can provide hydroelectric power, help reduce flood risk and store water to use later to irrigate crops, for drinking water and other purposes, their high ecological and socioeconomic costs mean they must prove their worth, and the case against them in our evolving energy sector is considerable. When and where new dams are proposed, we advocate for large-scale planning that factors in energy demand, other sources of renewable energy, project costs, and environmental and societal impacts. Our work within Brazil’s Tapajos River basin well illustrates this strategy put into action.

A Focus on Culverts

When roads cross streams—often over culverts—it can be problematic for the stream’s health and the safety of the road. Not only can poorly designed or undersized culverts hinder or block the migration of aquatic species, they can fail due to the increasing intensity of storms and growing development, which produces more runoff. TNC works with many partners to identify and fix problematic road crossings to enhance the movement of aquatic species as well as help road managers avoid tragedies, decrease much costlier emergency repairs and reduce expensive detours for travelers.

Explore examples of projects designed to address freshwater barriers that impact the movement of aquatic species, affect river health and impact people.

Protecting & Restoring Stream Flows

Obstacles aren’t an issue for aquatic species if there isn’t enough water to begin with. TNC employs an array of strategies aimed at improving or restoring “environmental” flows. Such work includes efforts to protect groundwater, modernizing the operations of dams, working with farmers to improve the efficiency of irrigated crops and the creation of water funds that help protect water sources and flows. See examples of such work .

Groundwater Isn’t Just Underground

Did you know that groundwater provides about 30% of the nation’s surface streamflow, according to estimates from the U.S. Geological Survey? The rest is from rain and snowmelt. And some systems are completely driven by groundwater or completely dependent.

Examples of Our Freshwater Work

The projects below are not a complete listing of the projects TNC is involved with to help improve the health of our freshwater systems. Rather, what’s listed below serve as some of our best examples, many of which feature videos.

Select Freshwater Projects

Click on each square to learn more.

Addressing Dams & Culverts

• Helping shape Brazil’s hydropower future .
• TNC is helping remove obsolete dams and plan for new ones in Europe .
• The largest dam removal project in Connecticut.
• Dam removals are helping “free” Kentucky’s Green River.
• Two dam removals and a fish passage made a big difference at Maine’s Penobscot River .
• Dam removals in Massachusetts brought back to life a “once-dead” river.
• Removing old dams created new hope for New Hampshire’s Bellamy River .
• Removing a dam helped improve the health of the Delaware River .
• TNC has prioritized dam removals throughout Tennessee.
• Removing “deadbeat” dams is reconnecting and restoring Vermont’s “broken streams.”
• TNC scientists recently detailed efforts to streamline culvert improvements in Maine.
• TNC received NOAA grants to improve culverts and bridges in North Carolina to improve fish passage and river health.
• TNC helped the State of Georgia produce a handbook to help improve the design of roads that cross streams .
• Tidal gates can also be a barrier for migrating fish; learn how TNC in Oregon addresses these to benefit salmon.
• This article published in TNC’s magazine provides an overview of work to address barriers to fish migration and the other impacts they have on people and nature.

Freshwater Restoration

• The restoration of 3,000 floodplain acres along 14 miles of the once-“channelized” Pocomoke River in Maryland.
• Nearly 150 projects in Oregon benefit salmon.
• Several projects in Ohio , funded through the state’s mitigation program, are improving river health.
• Projects in Arkansas benefit the Cache and Kings rivers.
• The reconnection of a 3.5-mile-long side channel along the lower Mississippi River.
• Restoring meanders to Montana’s Ruby River .
• Big lessons learned from the restoration of Little Creek in Missouri.
• Protecting and restoring Chinook and steelhead habitat in the upper Snake River in Idaho .
• Restoring spawning habitat in the Great Lakes.
• Restoring wetlands on Hawaii’s island of O’ahu.

Restoring Wetlands & Floodplains

• A 25-square-mile floodplain reconnection at “ Mollicy Farms ” along the Ouachita River in Louisiana.
• A 6,700-acre project at TNC’s Emiquon Preserve along the Illinois River in Illinois.
• A series of habitat reconnection projects on the Willamette River in Oregon.
• A 1,040-acre levee “setback” project along the Missouri River in Missouri.
• Work in Washington’s Puget Sound benefits salmon.
• Giving more room to the Sacramento River in California.
• Restoring tidal wetlands benefits salmon in Oregon.

Protecting and Restoring Stream Flows

• TNC is behind a myriad of efforts to protect groundwater that also supplies much of the flows in our rivers and streams. Learn more .
• The Sustainable Rivers Program improves the way many large dams are operated to produce more benefits and minimize environmental impacts.
• We work with farmers to reduce the amount of water they use to irrigate their crops. Our work in Nebraska , Arizona , Arkansas and other several states serve as prime examples of this strategy.
• We’re working to address water flows and water scarcity in a variety of different ways throughout the drought-prone Colorado River Basin in the U.S.
• TNC and its partners manage 32 Water Funds initiatives around the globe that provide a steady source of funding for the conservation of more than 7 million acres of watersheds and secure drinking water for nearly 50 million people. Colorado’s Yampa River Fund employs a variety of strategies aimed at protecting flows, and water funds we’ve helped launch in Africa and India that focus on agriculture improvements do as well. In Ecuador, two water funds are aimed at protecting water—and flows—at headwater sources.

Partnerships & Funding that Improve Freshwater

As an environmental non-profit organization, the support of our donors enables TNC to leverage its science-based expertise and past work to influence and implement new projects that improve the health of freshwater systems around the globe. It’s important to note, however, that in the face of so much loss and degradation of habitat, partnerships—and the funding they can provide—are paramount in order to work at scale and achieve meaningful results.

In the U.S., critical partnerships and related funding include, but are not limited to:

• The National Oceanic and Atmospheric Administration (NOAA)
• The National Fish Passage Program
• The U.S. Fish and Wildlife Service
• The U.S. Forest Service
• The Natural Resources Conservation Service
• The Bureau of Indian Affairs
• Native American Fish and Wildlife Society
• The Federal Highways Administration
• The National Fish Habitat Partnership
• American Rivers
• The Atlantic Salmon Federation
• Trout Unlimited
• Numerous state fish and wildlife agencies
• Many local U.S. Tribes and Canadian First Nations

Internationally, critical partnerships include, but are not limited to:

• Dam Removal Europe
• World Wildlife Fund
• World Fish Migration Foundation
• Wetlands International
• Fauna and Flora International
• Conservation International

Dive Deeper

Sustainable Rivers Program

The Nature Conservancy and the U.S. Army Corps of Engineers are finding new ways to strike a sustainable balance in how people use and protect the many benefits that rivers provide.

The Comeback: Alewives Return To Maine Rivers

Many of Maine’s rivers are experiencing a remarkable comeback. One of the world’s great migrations is returning to our waters. We’re talking about alewives!

Unleashing Rivers

New England’s waterways—the most heavily dammed in the United States—are making a comeback.

By Jenny Rogers

Essay on River Pollution

Students are often asked to write an essay on River Pollution in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on River Pollution

Introduction.

River pollution is a major environmental issue. It happens when harmful substances like chemicals, waste materials, or pollutants, are dumped into rivers.

Causes of River Pollution

The main causes are industrial waste, sewage, agricultural runoff, and littering. These pollutants can harm aquatic life and disrupt ecosystems.

Effects of River Pollution

Pollution affects all aspects of the river and its ecosystem. It harms animals, plants, and humans who depend on clean water.

Prevention of River Pollution

We can prevent river pollution by reducing waste, recycling, and treating sewage. Laws can also be enacted to protect our rivers.

Also check:

• Paragraph on River Pollution

250 Words Essay on River Pollution

River pollution has become a critical global issue, posing severe threats to ecosystems and human health. It is the contamination of rivers with harmful substances, often due to human activities, which disrupts the natural balance and biodiversity.

The primary cause of river pollution is industrialization. Industries often discharge untreated waste into rivers, leading to the accumulation of harmful chemicals. Similarly, agriculture contributes to river pollution through the excessive use of fertilizers and pesticides, which eventually leach into rivers.

River pollution affects both aquatic life and humans. The toxic substances can cause diseases and death among aquatic organisms, leading to a decline in biodiversity. For humans, polluted river water can cause severe health issues, including waterborne diseases and poisoning.

Preventing River Pollution

Preventing river pollution requires a multi-faceted approach. Strict regulations must be enforced to ensure industries treat their waste before disposal. Sustainable farming practices can also reduce the amount of agricultural runoff entering rivers.

In conclusion, river pollution is a grave issue that needs urgent attention. By understanding its causes and effects, we can take the necessary steps to prevent it and protect our rivers for future generations.

500 Words Essay on River Pollution

Rivers, the lifeblood of our planet, have been a vital part of human civilization since time immemorial. They provide water for drinking, irrigation, and transportation, and also support biodiversity. However, in recent years, river pollution has emerged as a grave concern. This essay delves into the causes, impacts, and potential solutions to river pollution.

River pollution is primarily caused by human activities. Industrialization is a significant culprit, with factories often discharging toxic waste directly into rivers. These wastes contain harmful chemicals and heavy metals, which not only contaminate the water but also harm aquatic life.

Another major cause is urbanization. Rapid, unplanned urban development leads to improper waste management, resulting in municipal waste, including non-biodegradable plastics, finding their way into rivers. Additionally, agricultural practices contribute to river pollution. Excessive use of fertilizers and pesticides seeps into rivers through runoff, causing nutrient pollution.

Impacts of River Pollution

The impacts of river pollution are multifaceted and devastating. Aquatic life is the most affected, with many species becoming extinct due to toxic pollutants. The loss of biodiversity disrupts the ecological balance, leading to unforeseen consequences.

For humans, polluted rivers pose serious health risks. Consuming contaminated water can lead to diseases like cholera, typhoid, and hepatitis. Furthermore, it impacts livelihoods dependent on rivers, such as fishing and tourism.

Lastly, polluted rivers can lead to eutrophication, a phenomenon where excessive nutrients cause a dense growth of plant life, leading to oxygen depletion in the water. This can result in ‘dead zones’, where no aquatic life can survive.

Solutions to River Pollution

Addressing river pollution requires a multi-pronged approach. At the forefront should be stricter regulations and enforcement for industrial waste disposal. Industries should be encouraged to adopt cleaner production methods and invest in effective waste treatment before disposal.

Urban planning needs to focus on efficient waste management systems to prevent municipal waste from reaching rivers. Public awareness campaigns can play a crucial role in reducing littering and promoting recycling.

In agriculture, promoting organic farming and efficient irrigation systems can significantly reduce the amount of pollutants reaching rivers.

Lastly, regular monitoring and cleanup of rivers are essential. Governments, NGOs, and communities should collaborate in these efforts to restore the health of our rivers.

River pollution is a pressing issue that threatens our environment, health, and livelihoods. While the problem is complex, it is not insurmountable. By combining regulatory measures, technological innovation, public awareness, and community participation, we can combat river pollution. The health of our rivers is a reflection of our relationship with nature, and it is high time we took decisive action to protect these vital ecosystems.

That’s it! I hope the essay helped you.

If you’re looking for more, here are essays on other interesting topics:

• Essay on Radioactive Pollution
• Essay on Prevention of Water Pollution
• Essay on Pollution Our Greatest Enemy

Apart from these, you can look at all the essays by clicking here .

Happy studying!

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

NOTIFICATIONS

Human impact on rivers.

• + Create new collection

Human beings have an impact on river ecosystems . The relationship living organisms have with each other and with their environment is extremely complex. Impacts on a species or a non-living element may have long-term consequences for a river ecosystem.

Several key areas of human impact on river ecosystems are:

• flow modifications
• exotic species
• harvesting.

Pollution is difficult to control because it is often the result of human infrastructure around a river. Pollution enters the river, sometimes in small amounts, at many different locations along the length of the river. Common sources of pollution come from rural and urban areas.

The clearing of forests to produce farmland has led to on-going erosion, with large quantities of sediment deposited into rivers. Agricultural intensification (substantial increases in fertiliser application and increased stock numbers) has resulted in nutrient and chemical loss to nearby streams and rivers. Elevated nutrient concentrations (especially nitrogen and phosphorus – key components of fertilisers) can result in the eutrophication of slow-moving waterways.

Urban areas add to this pollution when contaminants (PAHs and heavy metals) are washed off hard surfaces such as roads and drain into water systems. Sulfur dioxide and nitrous oxide emitted from factories and power stations enter river systems through acid rain. Sewage and effluent are discharged into rivers in some areas.

Pollution can lower the pH of the water, affecting all organisms from algae to vertebrates. Biodiversity decreases with decreasing pH.

Farmers, industry and local authorities are working together to reduce direct pollution from entering New Zealand rivers.

Flow modifications

Dams alter the flow, temperature and sediment in river systems. Reduced flow alters aquatic habitats – reducing or removing populations of fish, invertebrates and plants that depend on the flow to bring food. Reduced flow also decreases tributary stream flow, changing habitats and altering the water table in the stream aquifer. Consequently, riverside vegetation may be affected and decline in numbers. This may affect animal biodiversity, for example, bird species may leave the area if their habitat is lost or altered.

Changes in water temperature due to flow modification can affect insect development by not allowing them to complete their life cycle.

Rivers are connected systems, and barriers such as dams, culverts and floodgates disconnect one area from another. They prevent species such as eels from migrating – isolating previously connected populations.

Water taken from rivers for irrigation can lower river flows (a concern in Canterbury).

Exotic species

Exotic species have been introduced to river systems sometimes intentionally (for example, for fishing purposes or as food for other species) and sometimes unintentionally (for example, species come in on the bottom of boats or on fishing gear or they escape from pond areas during flooding, such as koi carp ).

These organisms can affect native species. They may compete with them for prey and habitat. They may prey on native species, alter habitats, breed with native species to produce another species or they may introduce harmful diseases and parasites. Once established, these species can be difficult to control or eradicate, particularly because of the connectivity of the flowing river. They can easily migrate to many areas affecting native species.

Excessive fishing in river ecosystems can drastically reduce numbers of species. For example, numbers of eels and whitebait in the Waikato River have reduced since the 1970s. Commercial eeling began in the 1960s and peaked in the 1970s with an annual average catch of 2000 tonnes. In the early 1980s, 400–450 tonnes per annum were harvested, with less than 200 tonnes per annum harvested since 2000.

Whitebait tonnage has also drastically reduced from an average of 46 tonnes per annum in the 1950s to 3 tonnes in 2000. Reducing stocks of a particular species can have an effect on other species such as birds that feed off river fish. The birds leave the area when river fish decline. Find out more about whitebaiting .

Nature of science

Scientific research sometimes reveals environmental problems can be linked to human activity. This balance between environmental needs and our needs is often the subject of debate involving scientists, iwi, environmentalists, authorities and local people. Such discussion can lead to further science exploration and possible solutions.

Activity ideas

The activity, River connections helps students visualise the interdependence within the river environment.

The activity Monitoring stream health and interactive Stream health monitoring and assessment provide step-by-step instructions, protocols, recording sheets and how-to videos for monitoring stream health.

Related content

The level 3 Connected article Testing the waters describes how scientists use the nature of science to investigate freshwater pollution.

See our newsletters here .

Would you like to take a short survey?

This survey will open in a new tab and you can fill it out after your visit to the site.

Advertisement

Establishment and application of ecological health evaluation system for urban and rural rivers in Yangtze Estuary

• Research Article
• Open access
• Published: 23 May 2023
• Volume 6 , article number  9 , ( 2023 )

Cite this article

You have full access to this open access article

• Biaobiao Peng 1 ,
• Benwei Shi 1 , 2 ,
• Ya Ping Wang   ORCID: orcid.org/0000-0002-8771-465X 1 , 3 ,
• Jingjing Li 1 ,
• Xinmiao Zhang 1 ,
• Xiaoyu Liu 1 ,
• Anglu Shen 5 &
• Yifan Ding 6  

1155 Accesses

Explore all metrics

The assessment of river ecosystem health is crucial for improving river resilience, achieving ecological protection and rational utilization in the Yangtze Estuary region where there is high utilization of rivers and a high demand for quality rivers by Shanghai, the world's largest modern city. To assess the ecological health status of Yangtze Estuary rivers, this study established a river health assessment model consisting of five dimensions: water quality, river landscape, aquatic organisms, river hydrology, and human interference, and a total of ten indicators based on the ecological survey results in the summer and autumn of six river channels in Chongming Island in the Yangtze Estuary. The evaluation results reveal that the health status of rural rivers in the northwest and east of Chongming Island (S2, S3) is the best, reaching an excellent level, while the small river in the central part of Chongming Island (S6) is the worst, reaching a somewhat inferior level. Compared with rural rivers, the comprehensive evaluation results of urban rivers are good or ordinary level. The high proportion of building area on both sides of the river and the low vegetation cover are the main factors that restrict their scoring results. In contrast, rural rivers need to focus on the area of buffer zones such as forests and vegetation on both sides of the river, river connectivity, appropriate widening of narrow rivers, regular cleaning and dredging of rivers, as well as reducing human interference with the rivers. Regarding seasonal changes, the health assessment results of Chongming Island rivers in summer are better than those in autumn, and the differences between sites in summer are slightly greater than those in autumn. The seasonal differences between sites are mainly due to changes in indicators of the diversity of zooplankton, phytoplankton, and macrobenthos. To further improve the ecological health of rivers, measures of ecological restoration could be adjusted based on regular health assessment and health weakness analysis.

Similar content being viewed by others

The Review of River Health Assessment in China

Comprehensive River Health Assessment System for Indian Rivers: A Case Study of Central Indian River Narmada

Assessment of river ecosystem health in Tianjin City, China: index of ecological integrity and water comprehensive pollution approach

Avoid common mistakes on your manuscript.

1 Introduction

Rivers provide human beings with various ecological services such as water sources, biological protection, and landscape, and promote the development of cities with their natural, social, economic, and environmental values. However, with the development of human society, the disturbance to rivers is increasing day by day. Dam construction, water intake, diversion, turning straight, blocking the Han River and the solidification of the river bank, and the destruction of the riparian vegetation zone have disturbed the river flow pattern and hydrological cycle process, and have synergistic effects with water pollution and excessive utilization of aquatic organisms, resulting in the degradation of the river ecosystem (Poff et al. 1997 ; Aguiar et al.  2010 ; Chovanec et al. 2015 ). The river’s ecological degradation has threatened public interests, which makes it increasingly urgent in social needs to improve the quality of the river’s ecological environment. The health of the river ecosystem has attracted the attention of governments and academia. A healthy river ecosystem has become an important management goal.

The connotation of "health" constitutes the focal point of the conceptual framework for ecosystem health assessment. Due to its ambiguous and abstract nature, the precise definition of ecosystem health has been a subject of controversy (Costanza et al. 1992 ; Rapport 1989 ; Peng et al. 2007 ; Liu et al. 2010 ). Over the past few decades, scholars have engaged in extensive theoretical discussions on the definition of "health" (Schaeffer et al.  1988 ; Meyer 1997 ; Boulton 1999 ). Previous research has defined ecosystem health from diverse disciplinary perspectives and case studies, which can be broadly categorized into biological ecology definitions and ecological economics definitions. The former underscores the natural ecological aspects of the ecosystem while disregarding socioeconomic and human health factors. The latter regards humans as integral parts of an ecosystem and accounts for the health of the ecosystem, as well as the extent to which it meets human needs and desires, namely, ecosystem services. In the early stages of research, the definition of river health was mainly focused on the natural properties of rivers. Karr defined river ecological integrity as health (Karr 1999 ), while Simpson defined river health as the main process of support and maintenance by the river ecosystem to restore its previous undisturbed capabilities (Simpson et al. 1999 ). The undisturbed state of rivers was considered as healthy. However, due to the severe impact of human activities on urban rivers during the process of urbanization and development, it is difficult to return to an undisturbed state even after the ecological restoration of urban rivers. Furthermore, urban rivers not only need to sustain their own ecosystem structure and functions but also need to provide corresponding ecological services for urban residents.

Currently, most scholars maintain that ecosystem health pertains to the ability of regional ecosystems to sustainably maintain spatial structure and ecological processes, self-regulation, restoration, and meet the reasonable needs of human society. Researchers have applied this concept to river health management and have scientifically evaluated the status of river ecosystems from the perspectives of water quality, biology, and ecology, with the aim of enhancing river management. The United States, Australia, the United Kingdom, South Africa, and other countries have successively carried out research and practice on river health evaluation and formed a series of evaluation methods such as RIVPACS, AUSRIV AS, IBI, RCE, ISC, and RHP (Bain et al.  2000 ; Ladson et al. 1999 ; Karr 1999 ; Munné  et al. 2003 ; Brizga et al. 2000 ).

As the concept of ecosystem health was applied to urban rivers, the assessment and research on urban river health achieved some development in China. Some Chinese experts learn from the advanced experience of foreign countries to screen different indicators, trying to establish a river health index system and apply it to river management. Such as Zhao and Yang built an index system based on five factors including water quantity, water quality, aquatic organisms, physical structure, and riparian zone, and used it to evaluate river health in the city of Ningbo (Zhao et al. 2005 ). Deng et al. established the indicator-based assessment system of urban river health and applied it to river management in Lijiang. The system was composed of three first-tier indexes, including natural biology, social economy, and landscape environment, as well as twenty-four second-tier indexes (Deng et al. 2014 ). Peng constructed the ecological assessment system of rivers and lakes based on the five aspects of hydrology and water resources, the physical form of rivers and lakes, water quality, aquatic organisms, and the social service function of rivers and lakes (Peng 2018 ). Some scholars have considered the impact of human activities when assessing the health of natural ecosystems and incorporated such factors into their models (Liao et al. 2018 ; Sun et al. 2019 ), while there has been a lack of reported evaluation models that include the influence of human activities in river health assessments.

The Yangtze Estuary has a unique geographical location, which is affected by both rivers and offshore. The environmental factors are complex and changeable, and the biological communities are rich. There are both broad coastal wetlands and towns with high-density populations, which also makes river ecosystem health management in the region challenging.

Chongming Island is located in the Yangtze Estuary and is surrounded by water, and the island is full of ditches and rivers, and the water system is rich, including urban rivers and suburban rivers, and the river’s ecological environment is complex and changeable. With the development of the social economy, the river ecosystem of Chongming Island encountered some difficulties, And there are differences between different regions, for example, rivers near urban and rural areas are mainly affected by domestic sewage, and human activities, while suburbs are mainly affected by agricultural production (Sun et al. 2009 ; Qian et al. 2011 ; Shen et al. 2017 ). However, in recent years, the situation has developed in a good direction, and the Chongming district government pays more and more attention to river ecological environment protection and adheres to the priority of ecological protection, the green transformation of the industry, and has carried out a series of river ecological governance and restoration projects, the river ecological environment has changed (Zhang et al. 2013a , b ; Tian 2021 ; Xin 2022 ), in order to better manage the river, as well as build a world-class ecological island, it is necessary to assess the river ecological health status of Chongming Island that research results can provide a reference for river health management.

There is a wide divergence between different regions in terms of urban river characteristics in China which leads to the fact that river health assessment indicators and criteria for a city are not applicable elsewhere. So a regional river ecological health assessment system needs to consider the local actual situation to select the appropriate indicators and standards to establish. Taking into account the aforementioned considerations and in accordance with the concept of ecological health, we propose a definition of river health that draws upon commonly utilized river health indicators both domestically and internationally, while also considering the actual circumstances of the Yangtze Estuary. This definition comprises the following criteria. (1) Healthy river water quality that conforms to the corresponding water function standards, devoid of eutrophication, and without the risk of pollutant discharge into the water. (2) Healthy riverbank environments characterized by a certain level of vegetation coverage, capable of fulfilling ecological buffer functions, providing biological habitats, and contributing to aesthetic beauty and recreation. (3) Healthy aquatic organisms characterized by relatively rich species composition and population size, with a certain level of biodiversity. (4) A physically healthy river possessing a diverse and meandering flow state, maintaining a certain longitudinal continuity, and capable of preserving hydraulic connections without disrupting flood control. (5) The last healthy river received moderate human disturbance.

2 Study area and methodology

2.1 survey sites.

Chongming Island is located in the Yangtze Estuary and is surrounded by water, and the island is full of ditches and rivers, and the water system is rich, urban rivers and rural rivers are interconnected and run through the entire island, but they have their own characteristics (Fig.  1 ). Urban rivers serve the city and are often densely populated along the banks. Their main functions include flood control, drainage, transportation, recreation and entertainment, environmental improvement, coordination of urban development, and adjustment of local microclimates. In contrast, rural rivers often run through farmland, forests, and wasteland, mainly serving flood control, drainage, irrigation, domestic water supply, aquaculture, ecosystem restoration, and recreation and entertainment needs. In order to establish a more suitable and comprehensive river health assessment system for the Yangtze Estuary, we selected 6 river sections with different significance in Chongming Island. The S1 river section is located in the south-central part of Chongming Island, east–west trending, close to the densely populated Bao town (Fig.  1 ). It belongs to the urban type of river. The S2 river section is located in the northwest of Chongming island, with both sides of the distribution of ecological farmland and wetland park. It belongs to the countryside suburban rivers, less disturbed by a human. The S3 section of the river is located at the eastern end of Chongming Island, close to the Chongming Dongtan National Bird Sanctuary, with many ecological farms and wetland parks nearby, and it belongs to the countryside suburban rivers, less disturbed by a human. The S4 river section is located at the western end of Chongming Island, near Chongming Xisha National Wetland Park and Mingzhu Lake. Towns and Villages are scattered on both sides of the river, and the impact of human activities is more obvious. The S5 river section also passes through the densely populated area, but the river is north–south, connecting the north branch and the south branch. It belongs to the urban type of river. The water level of the Chongming inland river is flexibly regulated by way of water diversion from the south sluice and drainage from the north sluice. The S6 river section is located in the middle of Chongming Island, which is a small section, but it is connected with Huabo Cultural Park, which makes us very interested (Fig.  1 ). We carry out satellite remote sensing observations on these river sections to obtain data on the vegetation coverage of the river bank, the proportion of farmland area, the proportion of road area, and the proportion of building area to analyze the impact of human activities. And hydrological surveys such as river width, connectivity, and curvature were conducted on these river sections. In addition, we also select a site in each section of the river water quality, macrobenthos, zooplankton, and algae survey.

Locations of study areas showing river sections and sites, The blue line represents the river network formed by the rivers of Chongming Island

2.2 Survey and analytical methods

Drawing on Wu and Wang's research, 12 alternate indicators were selected, and the final indicators were determined after screening through correlation analysis and principal component analysis (Wu et al. 2006 ; Xu et al. 2022 ). The data is obtained as follows.

Water quality indicators were monitored in accordance with the Technical Specifications for Monitoring Surface Water and Sewage (HJ/T91-2002) (Fig.  2 a).

( a ) Collecting water samples; ( b ) Collecting phytoplankton samples; ( c ) Collecting zooplankton samples; ( d ) Preservation and fixation of samples; ( e ) Collecting macrobenthos samples; ( f ) Separating and screening samples; ( g ) Laboratory identification

Plankton survey methods are carried out in accordance with the Code for the Survey of Fishery Resources in Reservoirs (SL 167–2014). Three indicators were selected for a comprehensive evaluation, including the number of algae taxa, the Shannon–Wiener diversity index of algae, and the Berger–Parker dominance index of algae. The indicators were standardized first, and then, the arithmetic means the sum of the three indicators was calculated. Finally, get the Comprehensive index of phytoplankton diversity (Fig.  2 b, 2c, 2d).

Macrobenthos are obtained by 1/16 Peterson mud miners (large). Samples are fixed on-site (if desired) and then refrigerated and brought back to the laboratory for identification, counting, and biomass determination. The index integration method was the same as that of phytoplankton (Fig.  2 e, 2f, 2g).

The extent of vegetation cover and the impact of human activities on the banks is obtained by analyzing satellite remote sensing data.

The satisfaction degree of residents regarding the landscape close to the river and the degree and influence of river reconstruction were obtained by the method of questionnaire survey.

Data on vegetation coverage and human activities such as the proportion of coastal farmland area, the percentage of coastal hardened roads area, and the proportion of coastal buildings area are obtained from remote sensing imagery (Sentine-2 and SuperView-1).

The data of indicators in terms of the physical structure of rivers such as river width, connectivity, and river curvature obtained by field survey measurements.

2.3 Identification of index weight

There are many ways to determine the weight of river health assessment indicators (Geng et al. 2006 ; Gao et al. 2007 ; Wang et al 2007 ; Xia et al. 2007 ), While studying the quality evaluation of river habitats, Wang found that the evaluation system established by principal component analysis was more in line with the real situation (Wang et al. 2017 ). Therefore, this study uses the method of principal component analysis to determine the weight of the index. The specific methods are as follows. First, standardize the raw data. Standardization of raw data by minimum range standardization. Then, the correlation coefficient matrix and principal component model are established, the eigenvalues of the principal components of each index are obtained, and the weights of each index are derived. Of course, these calculations can be made with the statistical analysis software SPSS18.0.

2.4 River health assessment

The model of river health assessment is expressed as,

which \({I}_{CH}\) is the river health evaluation index; B i is standardized for river health indicator; W i is the weight of river health assessment indicator. River health standards are divided into five grades, 0.8–1 is excellent, 0.6–0.8 is good, 0.4–0.6 is ordinary, 0.2–0.4 is somewhat inferior, and 0–0.2 is inferior.

3 Results and analysis

3.1 assessment indicators.

In order to avoid overlapping between indicators, the indexes under assessment were further analyzed and selected based on applied correlation analysis and principal component analysis. According to the Pearson correlation coefficient of all indicators, most indicators did not have a significant correlation. Only a few indicators, such as the proportion of hardened roads are significantly negatively correlated with the satisfaction rate of citizens, and there is a significant positive correlation between vegetation coverage and citizen satisfaction, so the indexes of citizen satisfaction were deleted. Besides the proportion of farmland land has a significant positive correlation with water quality and the proportion of coastal buildings. In order to avoid overlapping, the index of the proportion of farmland and cultivated land is deleted.

From the weights of the indicators, we can see that indicators such as water quality, aquatic organisms, river connectivity, and river width play a major role in the comprehensive assessment of rivers (weight > 0.2) (Table 1 ), while indicators such as vegetation coverage and human impact play a lesser role (wight < 0.05). Furthermore, the indicators such as the index of macrobenthos diversity and the proportion of building area along the coast are negative indicators, that is, the larger their values, the smaller the comprehensive evaluation result of the river.

3.2 Comprehensive health index

We can see that there are two sites in summer, namely S2 and S3, the comprehensive health index is greater than 80, reaching a very excellent level, only the S6 site is somewhat inferior level (Fig.  3 ). In the autumn, the comprehensive health index of most sites is in the good and ordinary level, and no site reaches the excellent level, so the overall comprehensive health evaluation results in summer are better than those in autumn. In summer, the comprehensive results of each site are quite different, while the difference in autumn is reduced, which is more similar to the results of the site.

Results of the comprehensive river health assessment at each site, S1 to S6 represent different river sections

In addition, we can also see that, regardless of summer or autumn, the comprehensive health evaluation results of S2 and S3 are the best, while S6 is the worst.

Comparing the comprehensive evaluation results in summer and autumn, it can be found that there are large changes between S1 and S2. By analyzing the radar map of S1, we can find that the increase in phytoplankton diversity and zooplankton diversity leads to an increase in comprehensive results in autumn than in summer (Fig.  4 , Fig.  5 ). By analyzing the radar map of S1, we can find that the increase in negative indicators of macrobenthos diversity, and the reduction of zooplankton diversity lead to an increase in comprehensive results in autumn than in summer (Fig.  4 , Fig.  5 ).

Score distribution of different indexes of the river section in summer. The indicators represented by each letter have the following meanings ( a ) Vegetation coverage; ( b ) River connectivity;( c ) River width; ( d ) Phytoplankton diversity; ( e ) Zooplankton diversity; ( f ) Macrobenthos diversity; ( g ) Proportion of building area; ( h ) River winding rate; ( i ) Proportion of hardened area;( j ) Water quality

Score distribution of different indexes of the river section in autumn, the index represented by each letter is the same as above

4 Discussion

In river health evaluation, the determination of weight is one of the important links. Once the weight deviates, it will directly lead to incorrect evaluation results and cannot match the actual situation. In the past river health evaluation, single-factor evaluation was performed on different indicators or a simple summation of multiple factors was performed, resulting in inaccurate results (Kleynhans 1996 ; Hao 2014 ). As a reliable weight determination method, principal component analysis is widely used in various evaluations (Yang et al. 2015 ; Shen et al. 2020 ; Zou et al. 2021 ), and Wang’s study found that the results calculated by the principal component analysis method are more scientific and more reasonable than the entropy weight method (Wang et al. 2017 ). Therefore, in this study, principal component analysis was used to calculate the weights. Through this method, ten indicators related to the comprehensive health evaluation of Chongming River were screened out (Table 1 ), and their respective weights were calculated. These weight of indicators are consistent with the research results of Su ( 2019 ) and Wu ( 2006 ). The assessment system can be successfully applied to the Chongming Island river health assessment, indicating that the assessment system is applicable to the river system in the Yangtze Estuary. In addition, a total of ten secondary indicators were selected in the evaluation system in this study. Compared with 17 indicators in Wu's study and 17 indicators in Xu's study, it is simpler and more convenient in practical application (Wu et al. 2006 ; Xu et al. 2022 ).

The evaluation model of this study not only screened out the indicators such as water quality, aquatic organisms, river connectivity, and river width that have an important impact on the overall health of the river but also comprehensively considered the impact of vegetation coverage and human impact. Because Chongming Island not only has relatively concentrated urbanized townships but also many farmland and countryside which is also a characteristic of the river ecosystem in the Yangtze Estuary, the general urban river health assessment model or mountain river model is not applicable here. So adding indicators such as human activities can better reflect the real situation and are more conducive to the later ecological management of rivers.

In addition, the weights of benthic biodiversity indicators and the proportion of building area in this model are negative, which is rare in other models. First of all, the construction area along the coast is negatively correlated with the health of the river, which is easy to understand. The larger the proportion of building area, the denser the population in this area, and the greater the negative impact of human activities such as water abstraction and sewage discharge on the river. According to the research findings of Ge et al. ( 2022 ) the degree of land use is the main factor affecting ecosystem health and the impact of the proportion of construction land on ecosystem health increases over time. The layout used in urban land use planning has a significant impact on ecosystem health. While the negative correlation between benthic indicators and river health is mainly because the benthic organisms in this study area are mainly fouling-tolerant benthic organisms. The more fouling-resistant benthic organisms, the worse the health of the river (Deng et al. 2005 ; Wang et al. 2012 a, 2012 b, Hooper et al. 2013 ). Negative weights rarely appear in the research of other scholars, because they have especially standardized these negative indicators in advance (Wang et al. 2017 ). However, this will reduce the differences between sites and the results are not so intuitive. In order to ensure accuracy and scientific research, this study does not make special treatment for these negative indicators. To enhance the ecological health of rivers, it is essential to develop a rational riparian land use plan that regulates coastal construction and minimizes disturbances. Additionally, strict control measures should be enforced to prevent sewage discharge and domestic waste dumping into the river. Regular dredging of the river should also be conducted to mitigate sludge deposition.

In addition, the weights of the comprehensive water quality index, river connectivity, river width, comprehensive index of zooplankton diversity, the composite index of macrobenthos diversity, and comprehensive index of phytoplankton diversity are relatively high, which indicates that these indexes play an important role in river health assessment of the Yangtze Estuary. Therefore, more attention should be paid to these indexes.

Analysis of different research sites shows that the integrated assessment results of rural rivers S3 and S2 are the best (Fig.  3 ), which contradicts Jiang's research—the conclusion that the eutrophication of the northern water body of Chongming Island is more serious. The reason is that Jiang's research only takes the single dimension of nutrients as the starting point of the research (Jiang et al. 2019 ). In the comprehensive assessment of river health, a single indicator cannot be used. For example, if only considering the impact of human activities, the southern part of Chongming Island's result will be the worst with urbanization, the existence of more garbage floating objects, the high proportion of building areas, and the evaluation of a high degree of river bank solidification (Xu et al. 2005 ; Wang et al. 2021 ). However, this is not the case, river health assessment needs to consider multi-dimensional indicators (Peng et al. 2014 ), for example, S2 has higher vegetation coverage, river curvature, river width, and diversity of zooplankton and phytoplankton, so the comprehensive S2 evaluation result will be high, and the comparison is in line with the actual situation (Fig.  4 , Fig.  5 ). When studying the seasonal differences at these two sites, it was found that the water quality assessment score of S3 in autumn was lower (Fig.  4 , Fig.  5 ), which may be due to the influence of autumn agricultural harvesting activities. After the autumn harvest, there is a large amount of straw in the farmland, and returning the straw to the soil will increase the content of nitrate nitrogen in the soil. This will be washed into the river by rainwater, thereby affecting the water quality (Zhao et al. 2010 ). Although S2 also belongs to rural rivers, the S2 river is not directly connected to farmland but is separated by forest, vegetation, etc. The low score of the benthic biota index in S2 indicates that the sediment pollution in this river is more severe. In response to this situation, regular cleaning and dredging of the river should be carried out. Similarly, the comprehensive score of S6, which is also a rural river, is the worst. This is because the river is narrow, with poor connectivity and sediment accumulation. In addition, it is connected to the HuaBo Cultural Park, and the construction of HuaBo Cultural Park and a large number of tourists will have a negative impact on the health of the river. Therefore, it can be seen that when carrying out rural river management, it is necessary to retain buffer zones such as trees and vegetation on both sides of the river, improve connectivity, appropriately widen narrow rivers, regularly clean and dredge rivers, and reduce human activities that interfere with river health. Compared to rural rivers, urban rivers (S1, S4, and S5) show a generally average performance in a comprehensive evaluation. The high proportion of building area on both sides of the river and the low coverage of vegetation are the main factors limiting the evaluation results. Therefore, it is recommended to improve the health of urban rivers by rational planning of urban riverbank buildings and increasing vegetation coverage.

As for the seasonal differences of each site, the diversity of zooplankton, phytoplankton, and macrobenthos. For example, the autumn assessment results of S1 have improved compared with summer, mainly due to the increase in the diversity of zooplankton and phytoplankton, The assessment result of S2 in autumn is lower than that in summer, mainly because the diversity of macrobenthos is increased, which is a negative indicator, so the results of S2 in autumn are lower. The difference between the stations decreased in autumn, and the main reason may be related to the regulation system of "absorbing water in spring and draining in autumn" in the river channel of Chongming Island (Zhang et al. 2013a , b ; Pang et al. 2016 ) because the rivers of Chongming Island are connected to each other, the large-scale drainage and water exchange in autumn reduces the difference between the stations. The evaluation results of S6 were the worst, mainly because the diversity of zooplankton, phytoplankton, and benthic organisms were all low, which shows that the diversity of zooplankton, phytoplankton, and benthic organisms is particularly important in river health assessment. When monitoring and ecological restoration should focus on these indicators.

5 Conclusions

This study constructed an ecological health assessment method for the Yangtze Estuary and applied it to the Chongming Island river network. The main conclusions are as follows.a) According to the characteristics of the rivers in the Yangtze River estuary, an ecological health assessment system suitable for the rivers in the Yangtze River estuary was constructed with five dimensions including water quality, river landscape, aquatic organisms, river hydrology, and human interference, and ten indexes including comprehensive water quality index, vegetation coverage, the proportion of building area along the coast, comprehensive index of zooplankton diversity, the composite index of macrobenthos diversity, comprehensive index of phytoplankton diversity, river connectivity, river winding rate, river width, the proportion of hardened area along the coast.b) The ecological health assessment system is applied to quantify the river health on Chongming Island. The evaluation results showed that the health of rural rivers in the northwest and east of Chongming Island (S2, S3) was the best, reaching an excellent level, while the central rural river (S6) was the worst, ranging somewhat inferior level. The assessment of urban rivers reached the good or ordinary level. Overall, the summer river health assessment results were better than those in autumn on Chongming Island, with slightly greater differences between locations in summer than in autumn. The seasonal differences at different locations were mainly due to changes in the diversity of plankton, phytoplankton, and benthic fauna indicators. These indicators should be given special attention in monitoring and ecological restoration.c) Based on the results of this study, it is recommended to adopt different measures for managing and restoring urban and rural rivers, taking into account their respective characteristics. In urban rivers, it is required to improve their health by rationalizing the planning of buildings along the river and increasing vegetation coverage. For rural rivers, it is better to preserve buffer zones such as forests and vegetation along the riverbanks, improve the connectivity of the river, widen narrow river sections as appropriate, and carry out regular dredging to reduce human interference on the health of the river.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Aguiar FC, Ferreira MT, Moreira I (2010) Exotic and native vegetation establishment following channelization of a western Iberian river. River research and applications & Management 17(4–5):509–526

Google Scholar  

Bain MB, Harig AL, Loucks DP, Goforth RR, Mills KE (2000) Aquatic ecosystem protection and restoration: advances in methods for assessment and evaluation. Environ Sci Policy 3:89–98

Article   Google Scholar  

Boulton AJ (1999) An overview of river health assessment: philosophies, practice, problems and prognosis. Freshwater biology 41(2):469–479

Brizga S, Finlayson B (2000) River Management: The Australasian Experience. Geomorphology 41(4):V391-392

Chovanec A, Schiemer F, Waidbacher H, Spolwind R (2015) Rehabilitation of a Heavily Modified River Section of the Danube in Vienna (Austria): Biological Assessment of Landscape Linkages on Different Scales. Int Rev Hydrobiol 87(2–3):183–195

Costanza R, Norton B, Haskell B (1992) Ecosystem health: new goals for environmental management. Island Press, Washington, pp 1–25

Deng DG, Li HY, Hu WM, Zhou Q, Guo LG (2005) Effects of eutrophication on distribution and population density of Corbicula fluminea and Bellamya sp in Chaohu Lake. Chin J Appl Ecol 16(1):142–149

Deng XJ, Xu YP, Zhai LX, Liu Y, Li Y (2014) Establishment and application of the index system for urban river health assessment. Acta Ecol Sin 34:993–1001

Gao YS, Wang H, Wang F (2007) Construction of evaluation index system for river’s healthy life. Advances in Water Science 18(2):252–257

Zou X, Yang RH, Yang Z, Zheng ZW, Shi F, Chi SY, Zhu AM, Shao K, Yuan YJ, Wan CY (2021) Habitat health assessment of typical tributaries of the Yangtze River. Journal of Hydroecology 42(5):29–39

Ge FJ, Tang GL, Zhong MX, Zhang Y, Xiao J, Li JF, Ge FY (2022) Assessment of Ecosystem Health and Its Key Determinants in the Middle Reaches of the Yangtze River Urban Agglomeration, China. International Journal of environmental research and public health 19(2):771

Geng LH, Liu H, Zhong HP (2006) Indicators and criteria for evaluation of healthy rivers. J Hydraul Eng 37(3):253–258

Hao LX, Sun RH, Chen LD (2014) Health assessment of river ecosystem in Haihe river basin. China Environ Sci 13(2):147–163

Hooper HL, Sibly RM, Hutchinson TH, Maund SJ (2013) The influence of larval density, food availability and habitat longevity on the life history and population growth rate of the midge Chironomus riparius. Oikos 102(3):515–524

Jiang DG, Li JH, Xu JY, Zhang LT (2019) Three-dimensional fluorescence spectra of dissolved organic matter in a eutrophic river on Chongming Island. Journal of Hydroecology 40(3):33–40

Karr JR (1999) Defining and measuring river health. Freshw Biol 41(2):221–234

Kleynhans CJ (1996) A qualitative procedure for the assessment of the habitat integrity status of the Luvuvhu river (Limpopo system, South Africa). J Aquat Ecosyst Health 5(1):41–54

Ladson AR, White LJ, Doolan JA, Finlayson BL, Hart BT, Lake PS, Tilleard JW (1999) Development and testing of an Index of Stream Condition for waterway management in Australia. Freshw Biol 41(2):453–468

Liao C, Yue Y, Wang K, Fensholt R, Tong X, Brandt M (2018) Ecological restoration enhances ecosystem health in the karst regions of southwest China. Ecol Indic 90:416–425

Liu J, Zhang Z, Xu X, Kuang W, Zhou W, Zhang S, Li R, Yan C, Yu D, Wu S, Jiang N (2010) Spatial patterns and driving forces of land-use change in China during the early 21st century. J Geogr Sci 20:483–494

Meyer JL (1997) Stream health: incorporating the human dimension to advance stream ecology. J N Am Benthol Soc 16(2):439–447

Munné A, Prat N, Solà C, Bonada N (2003) A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index. Aquat Conserv Mar Freshwat Ecosyst 13(2):147–163

Pang CH, Tao J, Wu XH (2016) Comprehensive assessment of ecological harnessing project in strong tide river net. Yangtze River 47(1):15–22

Peng B, Wang HR, Wang RL, Han YL, Huang WH, Zhu YF (2014) Development of a River Health Assessment System for the Lower Yellow River. Journal of Hydroecology 35(6):81–87

Peng J, Wang Y, Wu J, Zhang Y (2007) Evaluation for regional ecosystem health: methodology and research progress. Acta Ecol Sin 27(11):4877–4885

Peng WQ (2018) Research on river and lake health assessment indicators standards and methods. Journal of China institute of water resources and hydropower research 16(5):394–404 ( +416 )

Poff LR, Allan JD, Bain MB, Karr JR, Prestegaard KL, Richter BD, Sparks RE, Stromberg JC (1997) The Natural Flow Regime. Bioscience 47(11):769–784

Qian XY, Shen G, Guo CX, Gu HR, Zhu Y, Wang ZQ (2011) Source apportionment and spatial heterogeneity of agricultural non-point source pollution based on water environmental function zoning. Transactions of the Chinese Society of Agricultural Engineering 27(2):103–108

Rapport DJ (1989) What constitutes ecosystem health? Perspect. Biol Med 33:120–132

Schaeffer DJ, Herricks EE, Kerster HW (1988) Ecosystem health: I Measuring ecosystem health. Environ Manag 12:445–455

Shen Z, Kong L, Li JP, Gu YN, Yang L, Zhang W, Wang LC, Zhang YL (2017) Characteristics of variation trend of nitrogen nutrient in rivers of Chongming island. J Anhui Agric Sci 45(18):58–62

Sheng Q, Wei J, Wu We W, Shen CC, Wang TY, Wang L (2020) Correlation between ecosystem health conditions and land use in Dawen River basin. Chin J Ecol 39(1):224–233

Simpson J, Norris R, Bannuta L (1999) AusRivAS- National River Health Program: User Manual Website Version. Canberra, Australia, Environment Australia

Su HD, Jia YW, Niu CW, Tong WJ (2019) Statistical analysis of river health assessment indicators and weight distribution. Water Resources Protection 35(6):138–144

Sun B, Tang J, Yu D, Song Z, Wang P (2019) Ecosystem health assessment: a PSR analysis combining AHP and FCE methods for Jiaozhou Bay, China. Ocean Coast Manag 168:41–50

Sun C, Chen ZL, Bi CJ, Liu YL, Zhang C, Wang DQ, Shi GT, Ye MW (2009) Evaluation on Environmental Quality of Heavy Metals in Agricultural Soils of Chongming Island. Shanghai Acta Geographica Sinica 64(5):619–628

Tian H (2021) Research and evaluation of agricultural non-point source pollution remediation and recycling with aquaculture tail water as core—Take a modern agricultural area as an example. East China normal university, Diss (In Chinese) pp2-13

Wang B, Liu D, Liu S, Zhang Y, Lu DQ, Wang LZ (2012) Impacts of urbanization on stream habitats and macroinvertebrate communities in the tributaries of Qiangtang River. China Hydrobiologia 680(1):39–51

Wang Q, Lu C, Li FY, Fan ZP (2017) River habitat quality assessment based on principal component analysis and entropy weight in Qinghe river. Ecological Science 36(4):185–193

Wang T, Tong CF, Wu FR, Cong TT, Zhao JC, Chen ZT (2021) Community composition and distribution characteristics of the benthic macroinvertebrates in the inland rivers of Chongming. Haiyang Xuebao 43(9):71–80

Wang Yu, Huang Q, Liu CM (2007) Method of evaluating river health based on system order entropy. Journal of China Hydrology 27(1):1–3

Wang Z, Zhang ZY, Zhang JQ, Zhang YY, Yan SH (2012) The fauna structure of benthic macro-invertebrates for environmental restoration in a eutrophic lake using water hyacinths. China Environ Sci 32(1):142–149

Wu AN, Yang K, Che Y, Yuan W (2006) Application of river health assessment for urban river management. China Environ Sci 26(3):359–363

Xia T, Zhu W, Jiang MY, Zhao LF (2007) Assessment of urban river habitats: application and methodology. Acta Sci Circum 27(12):2095–2104

Xin LX (2022) Overview of the current status of wetland water bodies and restoration and enhancement measures in Chongming eco-island. Shanghai Water Resources Planning and Design 5:9–13

Xu D (2005) Talking on the integrative regulation for diversion channel of Chongmingnanheng. Jilin Water Resources 2:34–35

Xu F, Wang YG, Wnag X, Wu DY, Wang YY (2022) Establishment and application of the assessment system on ecosystem health for restored urban rivers in North China. Int J Environ Res Public Health 19(9):5619

Yang S, Sun LP, Zhong Y, Du JS, Hu X (2015) The water quality assessment and eutrophication evaluation of Jinhe River. Ecological Science 34(5):105–110

Zhao P, Chen F, Li L (2010) Effects of straw mulching on inorganic nitrogen and soil urease in winter wheat field. Acta Agriculturae Boreali-Sinica 25(3):165–169

Zhang YC, Jiang DG, Li JH (2013) Characteristics of eutrophication and its affecting factors in gate-controlled river network system of Chongming Island. Journal of Lake Sciences 25(3):366–372

Zhang ZS, Cheng GF, Chen X, Zhu H, Wu ZF, Liu XG (2013) Purification of micro-polluted water in aquaculture pond by integrated oxidation pond and constructed wetland system. China Water & Wastewater 29(19):22–25

Zhao YW, Yang ZF (2005) Preliminary study on assessment of urban river ecosystem health. Adv Water Sci 16:349–355

Download references

Acknowledgements

We thank Haifei Yang for his assistance in collecting field data and doing laboratory analysis. Two anonymous reviewers are thanked for their critical and constructive comments on the original manuscript.

This study was financially supported by the Innovation Program of Shanghai Municipal Education Commission (2019–01-07–00-05-E00027), the National Natural Science Foundation of China (U2240220), the Open Research Fund of Key Laboratory of Ocean Space Resource Management Technology (KF-2022–105), and China Postdoctoral Science Foundation (2021M691023).

Innovation Program of Shanghai Municipal Education Commission,2019-01-07-00-05-E00027,Ya Ping Wang,National Natural Science Foundation of China,U2240220,Ya Ping Wang,Key Laboratory of Ocean Space Resource Management Technology，MNR,KF-2022-105,Benwei Shi

Author information

Authors and affiliations.

State Key Laboratory of Estuarine and Coastal Research, School of Marine Sciences, East China Normal University, Shanghai, 200062, China

Biaobiao Peng, Benwei Shi, Ya Ping Wang, Jingjing Li, Xinmiao Zhang & Xiaoyu Liu

Key Laboratory of Ocean Space Resource Management Technology, Ministry of Natural Resources, 310012, Hangzhou, China

Ministry of Education Key Laboratory for Coast and Island Development, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210093, China

Ya Ping Wang

Administrative Service Center of Shanghai Municipal Water Affairs Bureau, Shanghai, 200050, China

College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, People’s Republic of China

Shanghai Municipal Engineering Design Institute (Group) CO., LTD, Shanghai, China

You can also search for this author in PubMed   Google Scholar

Contributions

Study conception and design were conducted by Lei Mo, Anglu Shen, and Yifan Ding. Material preparation, data collection and analysis were performed by Mo, Anglu Shen, Yifan Ding, Biaobiao Peng, Jingjing Li, Xinmiao Zhang and Xiaoyu Liu. The first draft of the manuscript was written by Biaobiao Peng, Benwei Shi and Ya Ping Wang, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Ya Ping Wang .

Ethics declarations

Competing interests.

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Peng, B., Shi, B., Wang, Y.P. et al. Establishment and application of ecological health evaluation system for urban and rural rivers in Yangtze Estuary. Anthropocene Coasts 6 , 9 (2023). https://doi.org/10.1007/s44218-023-00024-8

Download citation

Received : 17 October 2022

Revised : 09 May 2023

Accepted : 09 May 2023

Published : 23 May 2023

DOI : https://doi.org/10.1007/s44218-023-00024-8

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• River ecosystem
• Ecosystem health assessment
• Chongming Island
• Indicator system
• Yangtze Estuary
• Find a journal
• Publish with us
• Track your research

Essay On River

500 words essay on river.

Rivers are the backbone of human civilizations which provide freshwater that is the basic necessity for human life. We cannot live without water and rivers are the largest water bodies for freshwater. In fact, all civilizations in the past and present were born near river banks. In other words, they are veins of the earth that make life possible. Through an essay on rivers, we will take a look at their importance and how to save them.

Importance of Rivers

We refer to rivers as the arteries of any country. No living organism can live without water and rivers are the most important source of water. Almost all the early civilizations sprang up on the river banks.

It is because, from ancient times, people realized the fertility of the river valleys. Thus, they began to settle down there and cultivate the fertile valleys. Moreover, rivers originate from mountains which carry down rock, sand and soil from them.

Then they enter plains and water keeps moving slowly from the mountainsides. As a result, they deposit fertile soil. When the river overflows, this fertile soil deposits on the banks of rivers. Thus, bringing fresh fertile soil constantly to the fields.

Most importantly, rivers help in agriculture. In fact, a lot of farmers depend on rivers for agricultural purposes. Rivers have the ability to turn deserts into productive farms. Further, we can use them for constructing dams as well.

Further, rivers also are important highways. That is to say, they offer the cheapest method of transport. Before road and railways, rivers were essential means of transportation and communication.

In addition, rivers bring minerals down from hills and mountains. We construct damns across the river for generating hydel power and also preserve the wildlife. Further, they also come in use for encouraging tourism and developing fisheries.

Save Rivers

As pollution is on the rise, it has become more important than ever to save rivers. We must take different measures to do so. First of all, we must use biodegradable cleaning products and not use chemical products for body washing.

Further, we must not waste water when we shower. After that, we must install the displacement device in the back of the toilet for consuming less water. It is also essential to turn the tap off while brushing or shaving.

Moreover, one must also switch off the lights and unplug devices when not in use. This way we save electricity which in turn saves water that goes into the production of electricity. Always remember to never throw trash in the river.

Insulating your pipes will save energy and also prevent water wastage. Similarly, watering the plants early morning or late evening will prevent the loss of water because of evaporation . Finally, try to use recycled water for a carwash to save water.

Get the huge list of more than 500 Essay Topics and Ideas

Conclusion of the Essay on River

Rivers are essential as they are nature’s blessings for human beings. It provides us with so many things but nowadays, they are being polluted on a very large scale. We must all come together to prevent this from happening and saving our rivers for a better future.

FAQ of Essay on River

Question 1: What is the importance of rivers?

Answer 1: Rivers are important as they carry water and nutrients to areas all around the earth. Further, rivers play quite an important part of the water cycle, as they act as drainage channels for surface water. Most importantly, they provide excellent habitat and food for many of the earth’s organisms.

Question 2: How can we protect our rivers?

Answer 2: We can protect our rivers by segregating our household garbage into biodegradable and non-biodegradable waste. Moreover, volunteering with NGOs and community groups is also great option to save rivers from pollution.

Customize your course in 30 seconds

Which class are you in.

• Travelling Essay
• Picnic Essay
• Our Country Essay
• My Parents Essay
• Essay on Favourite Personality
• Essay on Memorable Day of My Life
• Essay on Knowledge is Power
• Essay on Gurpurab
• Essay on My Favourite Season
• Essay on Types of Sports

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Download the App

The Nile Water: a River of History and Vitality

This essay about the Nile River Valley explores its historical significance, modern-day vitality, and the challenges it faces. It highlights the Nile’s role as a cradle of civilization, sustaining ancient societies like Egypt, while also serving as a vital lifeline for millions of people today. The essay discusses the importance of sustainable management practices to address issues such as pollution, water scarcity, and climate change, emphasizing the need for international cooperation to ensure the Nile’s continued health and prosperity.

How it works

The Nile River Valley stands as an emblem of ancient civilization and modern vitality, a testament to the enduring legacy of humanity’s interaction with nature. Stretching over thousands of miles through the heart of Africa, the Nile has nurtured civilizations, shaped cultures, and sustained life for millennia.

At the heart of the Nile’s significance lies its role as a cradle of civilization. The ancient Egyptians, recognizing the fertile potential of its floodwaters, established one of the world’s earliest and most sophisticated societies along its banks.

With ingenuity and resourcefulness, they harnessed the river’s power to cultivate crops, build monumental structures, and develop a complex system of governance and religion that left an indelible mark on human history.

Beyond its historical importance, the Nile River continues to be a lifeline for millions of people across the region. Its waters provide sustenance for agriculture, support ecosystems teeming with biodiversity, and serve as a vital source of drinking water and hydropower. In countries like Egypt and Sudan, the Nile is not just a river but a symbol of national identity and pride, weaving through the fabric of society and shaping the rhythms of daily life.

Yet, the Nile also faces a host of challenges in the modern era. Rapid population growth, urbanization, and industrialization have placed unprecedented pressure on its resources, leading to issues such as pollution, habitat destruction, and water scarcity. Climate change further exacerbates these challenges, altering rainfall patterns, increasing temperatures, and threatening the delicate balance of the Nile’s ecosystem.

Addressing these challenges requires a holistic approach that balances the needs of both people and the environment. Sustainable management practices, such as improved water conservation, ecosystem restoration, and integrated water resource management, are essential to ensure the long-term health and vitality of the Nile River Basin. International cooperation and collaboration among riparian countries are also critical to address transboundary issues and promote equitable sharing of water resources.

In conclusion, the Nile River stands as a symbol of resilience, adaptability, and interconnectedness, bridging the past with the present and offering hope for the future. Its rich history and vital importance underscore the need for responsible stewardship and collective action to safeguard this precious resource for generations to come. As we navigate the complexities of the modern world, let us draw inspiration from the Nile’s enduring legacy and work together to ensure its continued vitality and prosperity.

Cite this page

The Nile Water: A River of History and Vitality. (2024, May 12). Retrieved from https://papersowl.com/examples/the-nile-water-a-river-of-history-and-vitality/

"The Nile Water: A River of History and Vitality." PapersOwl.com , 12 May 2024, https://papersowl.com/examples/the-nile-water-a-river-of-history-and-vitality/

PapersOwl.com. (2024). The Nile Water: A River of History and Vitality . [Online]. Available at: https://papersowl.com/examples/the-nile-water-a-river-of-history-and-vitality/ [Accessed: 18 May. 2024]

"The Nile Water: A River of History and Vitality." PapersOwl.com, May 12, 2024. Accessed May 18, 2024. https://papersowl.com/examples/the-nile-water-a-river-of-history-and-vitality/

"The Nile Water: A River of History and Vitality," PapersOwl.com , 12-May-2024. [Online]. Available: https://papersowl.com/examples/the-nile-water-a-river-of-history-and-vitality/. [Accessed: 18-May-2024]

PapersOwl.com. (2024). The Nile Water: A River of History and Vitality . [Online]. Available at: https://papersowl.com/examples/the-nile-water-a-river-of-history-and-vitality/ [Accessed: 18-May-2024]

Don't let plagiarism ruin your grade

Hire a writer to get a unique paper crafted to your needs.

Our writers will help you fix any mistakes and get an A+!

Please check your inbox.

You can order an original essay written according to your instructions.

Trusted by over 1 million students worldwide

1. Tell Us Your Requirements

2. Pick your perfect writer

3. Get Your Paper and Pay

Hi! I'm Amy, your personal assistant!

Don't know where to start? Give me your paper requirements and I connect you to an academic expert.

short deadlines

100% Plagiarism-Free

Certified writers

Proposed Updates to Framework for Biological Integrity, Diversity and Environmental Health

Today, the U.S. Fish and Wildlife Service is proposing to both revise the existing Biological Integrity, Diversity, and Environmental Health (BIDEH) policy and implement a new rule that will guide management of national wildlife refuges. The proposals will help provide a consistent, transparent, and science-based approach for evaluating both existing and new management practices at national wildlife refuges, in support of the mission of the National Wildlife Refuge System. These proposals will support conservation throughout the Refuge System and equip wildlife refuge managers with a framework to better tackle the dual threats of climate change climate change Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale. Learn more about climate change and biodiversity loss. 

“These important updates will provide a consistent, transparent approach and help strengthen the Service’s ability to achieve the Refuge System mission to conserve, manage and restore fish, wildlife and plant resources on national wildlife refuges across the United States,” said Service Director Martha Williams. “This will ensure that our national wildlife refuges are a thriving and sustained network of healthy lands and waters that include imperiled species and diverse wildlife populations, all for the benefit of present and future generations.”

These proposals support the conservation of the broad array of fish, wildlife, plants and habitats on refuges by providing refuge managers with a framework by which to evaluate and implement management actions to protect vulnerable species, restore and connect habitats, promote natural processes, sustain vital ecological functions, incorporate Indigenous Knowledge, and increase resilience to climate change. The proposals also provide a decision framework for other management practices such as native predator control, invasive species invasive species An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars. Learn more about invasive species management, pesticide use, mosquito control and other practices. While the proposals direct a default position regarding the use of each practice, they also provide refuge managers with the flexibility to implement these practices as necessary to meet statutory requirements and the mission of their refuges.

The authority for the proposed revised policy and new rule is derived from the  National Wildlife Refuge System Improvement Act of 1997 , which requires the Secretary of the Interior, acting through the Service, to ensure that the biological integrity, diversity and environmental health of the Refuge System are maintained.

The proposed rule will publish in the Federal Register on February 2, 2024, opening a 30-day comment period until March 4, 2024. The notice will be available at  http://www.regulations.gov , Docket Number: FWS-HQ-NWRS-2022-0106 and will include complete details on the proposals on the national wildlife refuges and how to submit your comments.

The Refuge System is an unparalleled network of 570 national wildlife refuges and 38 wetland management districts. There is a national wildlife refuge national wildlife refuge A national wildlife refuge is typically a contiguous area of land and water managed by the U.S. Fish and Wildlife Service  for the conservation and, where appropriate, restoration of fish, wildlife and plant resources and their habitats for the benefit of present and future generations of Americans. Learn more about national wildlife refuge within an hour’s drive of most major metropolitan areas. More than 67 million Americans visit refuges every year. National wildlife refuges provide vital habitat for thousands of species and access to world-class recreation, from fishing, hunting and boating to nature watching, photography and environmental education.

The U.S. Fish and Wildlife Service works with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people. For more information, visit www.fws.gov , or connect with us through any of these social media channels:  Facebook ,  Instagram ,  X (formerly known as Twitter),  LinkedIn ,  YouTube and  Flickr .

Media Contacts

Latest press releases.

You are exiting the U.S. Fish and Wildlife Service website

You are being directed to

We do not guarantee that the websites we link to comply with Section 508 (Accessibility Requirements) of the Rehabilitation Act. Links also do not constitute endorsement, recommendation, or favoring by the U.S. Fish and Wildlife Service.

• Skip to main content
• Keyboard shortcuts for audio player

Your Health

• Treatments & Tests
• Health Inc.
• Public Health

Why writing by hand beats typing for thinking and learning

Jonathan Lambert

If you're like many digitally savvy Americans, it has likely been a while since you've spent much time writing by hand.

The laborious process of tracing out our thoughts, letter by letter, on the page is becoming a relic of the past in our screen-dominated world, where text messages and thumb-typed grocery lists have replaced handwritten letters and sticky notes. Electronic keyboards offer obvious efficiency benefits that have undoubtedly boosted our productivity — imagine having to write all your emails longhand.

To keep up, many schools are introducing computers as early as preschool, meaning some kids may learn the basics of typing before writing by hand.

But giving up this slower, more tactile way of expressing ourselves may come at a significant cost, according to a growing body of research that's uncovering the surprising cognitive benefits of taking pen to paper, or even stylus to iPad — for both children and adults.

Is this some kind of joke? A school facing shortages starts teaching standup comedy

In kids, studies show that tracing out ABCs, as opposed to typing them, leads to better and longer-lasting recognition and understanding of letters. Writing by hand also improves memory and recall of words, laying down the foundations of literacy and learning. In adults, taking notes by hand during a lecture, instead of typing, can lead to better conceptual understanding of material.

"There's actually some very important things going on during the embodied experience of writing by hand," says Ramesh Balasubramaniam , a neuroscientist at the University of California, Merced. "It has important cognitive benefits."

While those benefits have long been recognized by some (for instance, many authors, including Jennifer Egan and Neil Gaiman , draft their stories by hand to stoke creativity), scientists have only recently started investigating why writing by hand has these effects.

A slew of recent brain imaging research suggests handwriting's power stems from the relative complexity of the process and how it forces different brain systems to work together to reproduce the shapes of letters in our heads onto the page.

Your brain on handwriting

Both handwriting and typing involve moving our hands and fingers to create words on a page. But handwriting, it turns out, requires a lot more fine-tuned coordination between the motor and visual systems. This seems to more deeply engage the brain in ways that support learning.

Shots - Health News

Feeling artsy here's how making art helps your brain.

"Handwriting is probably among the most complex motor skills that the brain is capable of," says Marieke Longcamp , a cognitive neuroscientist at Aix-Marseille Université.

Gripping a pen nimbly enough to write is a complicated task, as it requires your brain to continuously monitor the pressure that each finger exerts on the pen. Then, your motor system has to delicately modify that pressure to re-create each letter of the words in your head on the page.

"Your fingers have to each do something different to produce a recognizable letter," says Sophia Vinci-Booher , an educational neuroscientist at Vanderbilt University. Adding to the complexity, your visual system must continuously process that letter as it's formed. With each stroke, your brain compares the unfolding script with mental models of the letters and words, making adjustments to fingers in real time to create the letters' shapes, says Vinci-Booher.

That's not true for typing.

To type "tap" your fingers don't have to trace out the form of the letters — they just make three relatively simple and uniform movements. In comparison, it takes a lot more brainpower, as well as cross-talk between brain areas, to write than type.

Recent brain imaging studies bolster this idea. A study published in January found that when students write by hand, brain areas involved in motor and visual information processing " sync up " with areas crucial to memory formation, firing at frequencies associated with learning.

"We don't see that [synchronized activity] in typewriting at all," says Audrey van der Meer , a psychologist and study co-author at the Norwegian University of Science and Technology. She suggests that writing by hand is a neurobiologically richer process and that this richness may confer some cognitive benefits.

Other experts agree. "There seems to be something fundamental about engaging your body to produce these shapes," says Robert Wiley , a cognitive psychologist at the University of North Carolina, Greensboro. "It lets you make associations between your body and what you're seeing and hearing," he says, which might give the mind more footholds for accessing a given concept or idea.

Those extra footholds are especially important for learning in kids, but they may give adults a leg up too. Wiley and others worry that ditching handwriting for typing could have serious consequences for how we all learn and think.

What might be lost as handwriting wanes

The clearest consequence of screens and keyboards replacing pen and paper might be on kids' ability to learn the building blocks of literacy — letters.

"Letter recognition in early childhood is actually one of the best predictors of later reading and math attainment," says Vinci-Booher. Her work suggests the process of learning to write letters by hand is crucial for learning to read them.

"When kids write letters, they're just messy," she says. As kids practice writing "A," each iteration is different, and that variability helps solidify their conceptual understanding of the letter.

Research suggests kids learn to recognize letters better when seeing variable handwritten examples, compared with uniform typed examples.

This helps develop areas of the brain used during reading in older children and adults, Vinci-Booher found.

"This could be one of the ways that early experiences actually translate to long-term life outcomes," she says. "These visually demanding, fine motor actions bake in neural communication patterns that are really important for learning later on."

Ditching handwriting instruction could mean that those skills don't get developed as well, which could impair kids' ability to learn down the road.

"If young children are not receiving any handwriting training, which is very good brain stimulation, then their brains simply won't reach their full potential," says van der Meer. "It's scary to think of the potential consequences."

Many states are trying to avoid these risks by mandating cursive instruction. This year, California started requiring elementary school students to learn cursive , and similar bills are moving through state legislatures in several states, including Indiana, Kentucky, South Carolina and Wisconsin. (So far, evidence suggests that it's the writing by hand that matters, not whether it's print or cursive.)

Slowing down and processing information

For adults, one of the main benefits of writing by hand is that it simply forces us to slow down.

During a meeting or lecture, it's possible to type what you're hearing verbatim. But often, "you're not actually processing that information — you're just typing in the blind," says van der Meer. "If you take notes by hand, you can't write everything down," she says.

The relative slowness of the medium forces you to process the information, writing key words or phrases and using drawing or arrows to work through ideas, she says. "You make the information your own," she says, which helps it stick in the brain.

Such connections and integration are still possible when typing, but they need to be made more intentionally. And sometimes, efficiency wins out. "When you're writing a long essay, it's obviously much more practical to use a keyboard," says van der Meer.

Still, given our long history of using our hands to mark meaning in the world, some scientists worry about the more diffuse consequences of offloading our thinking to computers.

"We're foisting a lot of our knowledge, extending our cognition, to other devices, so it's only natural that we've started using these other agents to do our writing for us," says Balasubramaniam.

It's possible that this might free up our minds to do other kinds of hard thinking, he says. Or we might be sacrificing a fundamental process that's crucial for the kinds of immersive cognitive experiences that enable us to learn and think at our full potential.

Balasubramaniam stresses, however, that we don't have to ditch digital tools to harness the power of handwriting. So far, research suggests that scribbling with a stylus on a screen activates the same brain pathways as etching ink on paper. It's the movement that counts, he says, not its final form.

Jonathan Lambert is a Washington, D.C.-based freelance journalist who covers science, health and policy.

• handwriting

Take the Quiz: Find the Best State for You »

What's the best state for you ».

US Proposes End to Federal Coal Leasing in Wyoming Powder River Basin

FILE PHOTO: Dump trucks haul coal and sediment at the Black Butte coal mine outside Rock Springs, Wyoming, U.S. April 4, 2017. REUTERS/Jim Urquhart/File Photo

(Reuters) - The Biden administration on Thursday proposed an end to future coal leasing on federal lands in Montana and Wyoming's Powder River Basin, the nation's most productive coal-producing region, in part because of the sector's emissions that worsen climate change.

The two proposals from the U.S. Bureau of Land Management respond to a 2022 federal court order requiring the agency to analyze the climate and public health impacts of burning fossil fuels in its land use plans for the areas.

The plans would not affect existing leases, and production would continue at mines in Wyoming until 2041 and in Montana until 2060, BLM said.

The agency noted the sharp decline in coal production in the region since its peak in 2008. Powder River Basin mines produced 258 million short tons of surface coal in 2022, down from 496 million in 2008, according to the Energy Information Administration. Wyoming accounts for most of that production.

Most Powder River Basin coal is used for electricity generation. EIA projects that by 2050, U.S. coal-fired generating capacity will be less than half of 2022 levels as the nation shifts to cleaner sources.

The decision marked a win for environmental groups that sued the agency to stop new coal leasing in the region.

"For years, conservation groups have litigated to get to this point — arguing that the federal government cannot simply lease away our public lands to coal companies while ignoring the impacts to public health," Drew Caputo, an attorney with Earthjustice, said in a statement. "We are grateful that the Biden administration has shown the courage to end coal leasing in the Powder River Basin and at long last turn the page on this climate-destroying fuel."

Senator John Barrasso of Wyoming said the decision would kill jobs and reduce revenues his state needs for schools, roads and other services.

"President Biden continues to wage war on Wyoming's coal communities and families," Barrasso said in a statement.

The release of the draft plans will kick off a 30-day comment period. BLM said it will approve the plans after resolving any protests or complaints during that time.

(Reporting by Nichola Groom; Editing by Aurora Ellis)

Copyright 2024 Thomson Reuters .

Join the Conversation

Tags: environment , United States , coal

America 2024

Health News Bulletin

Stay informed on the latest news on health and COVID-19 from the editors at U.S. News & World Report.

Sign in to manage your newsletters »

Sign up to receive the latest updates from U.S News & World Report and our trusted partners and sponsors. By clicking submit, you are agreeing to our Terms and Conditions & Privacy Policy .

You May Also Like

The 10 worst presidents.

U.S. News Staff Feb. 23, 2024

Cartoons on President Donald Trump

Feb. 1, 2017, at 1:24 p.m.

Photos: Obama Behind the Scenes

April 8, 2022

Photos: Who Supports Joe Biden?

March 11, 2020

Flag Display Rattles SCOTUS Experts

Lauren Camera May 17, 2024

Will Trump Testify in His Own Trial?

Laura Mannweiler May 17, 2024

Viral House Spat Shows Chaotic Congress

Aneeta Mathur-Ashton May 17, 2024

QUOTES: Trump on Gun Control Policy

Cecelia Smith-Schoenwalder May 17, 2024

Leading Indicators: Economy Is Softening

Tim Smart May 17, 2024

Key Moments From Cohen Cross-Examination

Laura Mannweiler May 16, 2024

• Share full article

Advertisement

Supported by

Guest Essay

As Bird Flu Looms, the Lessons of Past Pandemics Take On New Urgency

By John M. Barry

Mr. Barry, a scholar at the Tulane University School of Public Health and Tropical Medicine, is the author of “The Great Influenza: The Story of the Deadliest Pandemic in History.”

In 1918, an influenza virus jumped from birds to humans and killed an estimated 50 million to 100 million people in a world with less than a quarter of today’s population. Dozens of mammals also became infected.

Now we are seeing another onslaught of avian influenza. For years it has been devastating bird populations worldwide and more recently has begun infecting mammals , including cattle, a transmission never seen before. In another first, the virus almost certainly jumped recently from a cow to at least one human — fortunately, a mild case.

While much would still have to happen for this virus to ignite another human pandemic, these events provide another reason — as if one were needed — for governments and public health authorities to prepare for the next pandemic. As they do, they must be cautious about the lessons they might think Covid-19 left behind. We need to be prepared to fight the next war, not the last one.

Two assumptions based on our Covid experience would be especially dangerous and could cause tremendous damage, even if policymakers realized their mistake and adjusted quickly.

The first involves who is most likely to die from a pandemic virus. Covid primarily killed people 65 years and older , but Covid was an anomaly. The five previous pandemics we have reliable data about all killed much younger populations.

The 1889 pandemic most resembles Covid (and some scientists believe a coronavirus caused it). Young children escaped almost untouched and it killed mostly older people, but people ages 15 to 24 suffered the most excess mortality , or deaths above normal. Influenza caused the other pandemics, but unlike deaths from seasonal influenza, which usually kills older adults, in the 1957, 1968 and 2009 outbreaks, half or more deaths occurred in people younger than 65. The catastrophic 1918 pandemic was the complete reverse of Covid: Well over 90 percent of the excess mortality occurred in people younger than 65. Children under 10 were the most vulnerable, and those ages 25 to 29 followed.

Any presumption that older people would be the chief victims of the next pandemic — as they were in Covid — is wrong, and any policy so premised could leave healthy young adults and children exposed to a lethal virus.

The second dangerous assumption is that public health measures like school and business closings and masking had little impact. That is incorrect.

Australia, Germany and Switzerland are among the countries that demonstrated those interventions can succeed. Even the experience of the United States provides overwhelming, if indirect, evidence of the success of those public health measures.

The evidence comes from influenza, which transmits like Covid, with nearly one-third of cases transmitted by asymptomatic people. The winter before Covid, influenza killed an estimated 25,000 here ; in that first pandemic winter, influenza deaths were under 800. The public health steps taken to slow Covid contributed significantly to this decline, and those same measures no doubt affected Covid as well.

So the question isn’t whether those measures work. They do. It’s whether their benefits outweigh their social and economic costs. This will be a continuing calculation.

Such measures can moderate transmission, but they cannot be sustained indefinitely. And even the most extreme interventions cannot eliminate a pathogen that escapes initial containment if, like influenza or the virus that causes Covid-19, it is both airborne and transmitted by people showing no symptoms. Yet such interventions can achieve two important goals.

The first is preventing hospitals from being overrun. Achieving this outcome could require a cycle of imposing, lifting and reimposing public health measures to slow the spread of the virus. But the public should accept that because the goal is understandable, narrow and well defined.

The second objective is to slow transmission to buy time for identifying, manufacturing and distributing therapeutics and vaccines and for clinicians to learn how to manage care with the resources at hand. Artificial intelligence will perhaps be able to extrapolate from mountains of data which restrictions deliver the most benefits — whether, for example, just closing bars would be enough to significantly dampen spread — and which impose the greatest cost. A.I. should also speed drug development. And wastewater monitoring can track the pathogen’s movements and may make it possible to limit the locations where interventions are needed.

Still, what’s achievable will depend on the pathogen’s severity and transmissibility, and, as we sadly learned in the United States, how well — or poorly — leaders communicate the goals and the reasons behind them.

Specifically, officials will confront whether to impose the two most contentious interventions, school closings and mask mandates. What should they do?

Children are generally superspreaders of respiratory disease and can have disproportionate impact. Indeed, vaccinating children against pneumococcal pneumonia can cut the disease by 87 percent in people 50 and older. And schools were central to spreading the pandemics of 1957, 1968 and 2009. So there was good reason to think closing schools during Covid would save many lives.

In fact, closing schools did reduce Covid’s spread, yet the consensus view is that any gain was not worth the societal disruption and damage to children’s social and educational development. But that tells us nothing about the future. What if the next pandemic is deadlier than 1957’s but as in 1957, 48 percent of excess deaths are among those younger than 15 and schools are central to spread? Would it make sense to close schools then?

Masks present a much simpler question. They work. We’ve known they work since 1917, when they helped protect soldiers from a measles epidemic. A century later, all the data on Covid have actually demonstrated significant benefits from masks.

But whether to mandate masks is a difficult call. Too many people wear poorly fitted masks or wear them incorrectly. So even without adding in the complexities of politics, compliance is a problem. Whether government mask mandates will be worth the resistance they foment will depend on the severity of the virus.

That does not mean that institutions and businesses can’t or shouldn’t require masks. Nor does it mean we can’t increase the use of masks with better messaging. People accept smoking bans because they understand long-term exposure to secondhand smoke can cause cancer. A few minutes of exposure to Covid can kill. Messaging that combines self-protection with communitarian values could dent resistance significantly.

Individuals should want to protect themselves, given the long-term threat to their health. An estimated 7 percent of Americans have been affected by long Covid of varying severity, and a re-infection can still set it off in those who have so far avoided it. The 1918 pandemic also caused neurological and cardiovascular problems lasting decades, and children exposed in utero suffered worse health and higher mortality than their siblings. We can expect the same from the next pandemic.

What should we learn from the past? Every pandemic we have good information about was unique. That makes information itself the most valuable commodity. We must gather it, analyze it, act upon it and communicate it.

Epidemiological information can answer the biggest question: whether to deploy society-wide public health interventions at all. But the epidemiology of the virus is hardly the only information that matters. Before Covid vaccines were available, the single drug that saved the most lives was dexamethasone. Health officials in Britain discovered its effectiveness because the country has a shared data system that enabled them to analyze the efficacy of treatments being tried around the country. We have no comparable system in the United States. We need one.

Perhaps most important, government officials and health care experts must communicate to the public effectively. The United States failed dismally at this. There was no organized effort to counter social media disinformation, and experts damaged their own credibility by reversing their advice several times. They could have avoided these self-inflicted wounds by setting public expectations properly. The public should have been told that scientists had never seen this virus before, that they were giving their best advice based on their knowledge at the time and that their advice could — and probably would — change as more information came in. Had they done this, they probably would have retained more of the public’s confidence.

Trust matters. A pre-Covid analysis of the pandemic readiness of countries around the world rated the United States first because of its resources. Yet America had the second-worst rate of infections of any high-income country.

A pandemic analysis of 177 countries published in 2022 found that resources did not correlate with infections. Trust in government and fellow citizens did. That’s the lesson we really need to remember for the next time.

John M. Barry, a scholar at the Tulane University School of Public Health and Tropical Medicine, is the author of “The Great Influenza: The Story of the Deadliest Pandemic in History.”

The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips . And here’s our email: [email protected] .

Follow the New York Times Opinion section on Facebook , Instagram , TikTok , WhatsApp , X and Threads .

• SI SWIMSUIT
• SI SPORTSBOOK

Doc Rivers Fires Back at JJ Redick Calling Him Out

Joey linn | may 14, 2024.

• Los Angeles Clippers

During a segment of ESPN's First Take earlier this year, former NBA guard JJ Redick called out his former coach Doc Rivers, saying, "I've seen the trend for years. The trend is always making excuses. Doc, we get it. Taking over a team in the middle of a season is hard... But it's always an excuse. It's always throwing your team under the bus... There's never accountability with that guy."

Redick played under Rivers with the LA Clippers, and it seems the two did not always see eye to eye. In a recent appearance on The Stephen A. Smith show, Rivers addressed these comments from Redick, saying, "JJ has had a problem with me for a while. And that's fine... In JJ's case, we didn't sign him back with the Clippers. I stopped playing him as much because he wasn't very effective in the playoffs. That's all known... JJ Redick's best numbers of his career was under one coach and you're looking at him. I'm the one who grabbed him out of Milwaukee and decided to start him. From that point on, his career took off."

Doc Rivers Responds to JJ Redick: "JJ Redick best numbers of his career was under one coach and your looking at him. I'm the one who grabbed him out of Milwaukee and decided to start him. From that point on, his career took off" [via @TheSASshow ] pic.twitter.com/PHyfswTGZO — BASKETBALL ON 𝕏 (@BASKETBALLonX) May 14, 2024

Making sure to emphasize that Redick was not very effective in the playoffs, Rivers addressed why the former NBA guard feels a certain type of way about him, but also said he has no issue with that.

Related Articles

Philadelphia 76ers Star Reveals Honest Feelings on James Harden

Exclusive: Russell Westbrook Opens Up About Role With Clippers

James Harden Opens Up About Playing for Clippers After Rough Few Years

Title: Credentialed writer covering the NBA for Sports Illustrated's FanNation Email: [email protected] Education: Communication Studies degree from Biola University Location: Los Angeles, California Expertise: NBA analysis and reporting Experience: Joey Linn is a credentialed writer covering the NBA for Sports Illustrated's FanNation. Covering the LA Clippers independently in 2018, then for Fansided and 213Hoops from 2019-2021, Joey joined Sports Illustrated's FanNation to cover the Clippers after the 2020-21 season. Graduating from Biola University in 2022 with a Communication Studies degree, Joey served as Biola's play-by-play announcer for their basketball, baseball, softball, and soccer teams during his time in school. Joey's work on Biola's broadcasts, combined with his excellence in the classroom, earned him the Outstanding Communication Studies Student of the year award in 2022. Joey covers the NBA full-time across multiple platforms, primarily serving as a credentialed Clippers beat writer.

Follow joeylinn_

Time in Elektrostal , Moscow Oblast, Russia now

• Tokyo 06:15PM
• Beijing 05:15PM
• Kyiv 12:15PM
• Paris 11:15AM
• London 10:15AM
• New York 05:15AM
• Los Angeles 02:15AM

Time zone info for Elektrostal

• The time in Elektrostal is 8 hours ahead of the time in New York when New York is on standard time, and 7 hours ahead of the time in New York when New York is on daylight saving time.
• Elektrostal does not change between summer time and winter time.
• The IANA time zone identifier for Elektrostal is Europe/Moscow.

Time difference from Elektrostal

Sunrise, sunset, day length and solar time for elektrostal.

• Sunrise: 04:06AM
• Sunset: 08:40PM
• Day length: 16h 34m
• Solar noon: 12:23PM
• The current local time in Elektrostal is 23 minutes ahead of apparent solar time.

Elektrostal on the map

• Location: Moscow Oblast, Russia
• Latitude: 55.79. Longitude: 38.46
• Population: 144,000

Best restaurants in Elektrostal

• #1 Tolsty medved - Steakhouses food
• #2 Ermitazh - European and japanese food
• #3 Pechka - European and french food

Find best places to eat in Elektrostal

• Best pizza restaurants in Elektrostal
• Best restaurants with desserts in Elektrostal
• Best dinner restaurants in Elektrostal

The 50 largest cities in Russia

Idaho doctor with love of adventure dies in avalanche he apparently triggered while skiing

An Idaho emergency room doctor who connected adventure-seeking to acts of altruism died on Friday in an avalanche that he apparently triggered while skiing.

The Sawtooth Avalanche Center reported that a skier was killed on Friday while backcountry skiing on Donaldson Peak in Idaho’s Lost River Range. The Custer County coroner identified the skier as emergency department physician Dr. Terrence “Terry” O’Connor, according to Idaho Mountain Express .

O’Connor was on a down climb with another experienced backcountry skier Friday when he “triggered and was caught in a small wind slab avalanche,” the avalanche center reported. The slide then triggered a second, larger avalanche.

His skiing partner, who was not identified, called for help using a satellite communication device before following his path and locating him. They dug O’Connor out of the snow and began CPR.

A search-and-rescue team responded but O’Connor did not survive the accident, the avalanche center said.

The Idaho EMS Physician Commission confirmed his death in the accident in a statement posted to Facebook, saying O’Connor’s loss would be felt throughout the state and region.

“Terry was an outstanding physician and played a pivotal role in the early days of the COVID pandemic really demonstrating the public health role of the EMS medical director within a community,” the statement said.

O’Connor worked at the St. Luke’s Wood River Medical Center  in Ketchum, Idaho, according to the hospital’s website. It featured a blog written on O’Connor in 2021 describing his service to the community during the pandemic.

“I work in a small community, but I feel like I can still help with a global health problem,” O’Connor said at the time.

O’Connor also tied his inclination toward acts of selflessness and altruism to his love of adventure. According to the blog, O’Connor had gone to Mount Everest three times, the last of which he was able to summit.

He hosted a podcast called “The Adventure Activist,” which is described as a place for “meaningful conversation” with guests on how they add value to the world and “do some good with their passion for adventure.”

In a 2017 Tedx Talk called “A Life of Adventure: Selfish or Selfless?” O’Connor said his dear friend and climbing partner had died in an avalanche in the Canadian Rockies two weeks before his own adventure on Mount Everest. He questioned why he was seeking such a dangerous summit the entire time he climbed to the top of the mountain, O’Connor said.

Finally making it to the top, O’Connor said he was awestruck but that for some reason he thought suddenly on the death of a woman he met during work he did in Tibet earlier that year. She died of a preventable heart disease that O’Connor said could have easily been managed in a more developed country with resources.

His talk focused on the effect of that awe, noting that research indicated a connection to altruism.

“We’re finding that awe, like a community or religious experience, helps us to bind to others, motivating us to act in collaborative ways,” O’Connor said. “And individuals who experience awe more frequently in their daily lives are also more willing to sacrifice and give more resources to others.”

O’Connor said he looked forward to learning more and hoped others would go on their adventures.

“Whether you find your awe looking up at the trees in the night sky or in the mountains, these moments will always be oxygen for our souls,” O’Connor said. “I just ask you to remember why you might feel that way.”

Doha Madani is a senior breaking news reporter for NBC News. Pronouns: she/her.