The sustainability of water resources worldwide is increasingly imperiled as climate change contributes to the human-induced problems of water supply scarcity and maldistribution. Environmental ...problems associated with water quality, such as aquifer depletion, land subsidence, the seasonal drying of river flows, waterlogging, the salinization of rivers and groundwater, and human health problems from the excessive use of fertilizers and pesticides will require a radical re-thinking of resource-management policy and new tools to help analysts and regulators craft novel solutions. Over the past several decades, with the advent and rapid progress of computational technology, watershed models have increasingly become important and effective tools for tackling a wide range of water resource and environmental management issues and for supporting regulatory compliance. Statistical and machine-learning methods are being used to support and even supplant more traditional simulation models to improve the estimation of the temporal dynamics and patterns of variability in pollutant concentrations and loads. With the advancements in modeling approaches for water quality, there have also been developments in decision-support tools for water quality management. This reprint describes innovative decision-support approaches from around the world and across sectors that can be applied by stakeholders, government entities, and regulators to reduce environmental pollution and result in cost-effective and sustainable water management strategies.
Traditional urban drainage degrades receiving waters. Alternative approaches have potential to protect downstream waters, but widespread adoption requires robust demonstration of their feasibility ...and effectiveness. We conducted a catchment‐scale experiment over 19 years to assess the effect of dispersed stormwater control measures (SCMs), measured as a reduction in effective imperviousness (EI) on stream water quality in six sites on two streams. We compared changes in those sites over 7 years as EI decreased, to changes in the 12 preceding years, and in three reference and two control streams. SCMs reduced phosphorus concentrations and summer temperature to reference levels in dry weather where EI was sufficiently reduced, but effects were smaller with increased antecedent rain. SCMs also reduced nitrogen concentrations which were influenced by septic tank seepage in all sites. SCMs had no effect on suspended solids concentrations, which were lower in urban than in reference streams. SCMs increased electrical conductivity: along with reduced temperature this is evidence of increased contribution of groundwater to baseflows. This experiment strengthens inference that urban stormwater drainage increases contaminant concentrations in streams, and demonstrates that such impacts are reversible and likely preventable. Variation in degree of water quality improvement among experimental sites suggests that achieving reference water quality would require SCMs with large retention capacity intercepting runoff from nearly all impervious surfaces, thus requiring more downslope space and water demand. EI is a useful metric for predicting stream water quality responses to SCMs, allowing better catchment prioritization and SCM design standards for stream protection.
Plain Language Summary
The way we drain our cities and towns pollutes and erodes our streams and rivers. Water running off, and heated by, roofs and roads carries damaging particles and chemicals. The stormwater drains and pipes that we build transport the polluted runoff, quickly and untreated, to downstream waters. To test if creek water quality downstream of stormwater drainage can be restored, we conducted an experiment. 100s of rain‐gardens that allow water to soak into surrounding soils and be taken up by plants, and rainwater tanks for harvesting, were installed in two suburban catchments. We compared before and after conditions in creeks downstream of the treatments, with conditions in other degraded urban streams, and in undegraded forested streams. Filtering and harvesting stormwater reduced summer temperatures and reduced concentrations of phosphorus and nitrogen, critical contaminants for healthy streams. The reductions were greatest in dry weather, and after small amounts of rain. To achieve water quality similar to forested streams, we need rain‐gardens and harvesting systems that catch runoff from nearly every roof and road upstream. Achieving that will require reserving space near pipe outlets to streams for final treatment systems, and finding ways to use the excess water generated by roofs and roads.
Key Points
A long‐term catchment‐scale experiment strengthens inference that urban stormwater drainage increases stream contaminant concentrations
Extensive use of dispersed stormwater control measures can reverse stormwater‐induced degradation of stream water quality
Achieving reference stream water quality requires retention, treatment and loss of runoff from nearly all catchment impervious surfaces, with high performance standards
The purpose of this study was to evaluate groundwater quality and health risks of nitrogen pollution in the Shenfu mining area of northwest China. Statistical analysis, Durov diagrams, Gibbs diagrams ...and correlation analysis were applied to analyse the groundwater chemistry. Entropy weighted water quality index was applied for groundwater quality assessment. The non-carcinogenic risks to adults and children due to drinking nitrogen-contaminated groundwater were assessed using the models recommended by US Environmental Protection Agency. The study shows that the abundances of anions and cations are in the order of HCO
3
−
> SO
4
2−
> Cl
−
and Ca
2+
> Na
+
> Mg
2+
, respectively. Gibbs diagrams reveal that groundwater chemistry is mainly controlled by rock weathering. Cation exchange and the dissolution of aluminate minerals, carbonate minerals and halite are the main sources of major ions in the groundwater. More than half of the groundwater in the study area is medium quality, marginally suitable for multiple purposes. NH
4
–N, NO
2
–N and organic matter are the main pollutants which mainly derived from agricultural and industrial activities. The mean total hazard index (THI) value of nitrogen for adults and children is 1.563 and 3.126, respectively, which surpasses the permissible limit (THI = 1) recommended by USEPA. Moreover, the NO
3
–N level in some medium quality water, which is considered suitable for drinking purposes according to Chinese drinking water quality standards, poses high non-carcinogenic risks to adults and children. Therefore, the Chinese government should revise the concentration limit of NO
3
–N (20 mg/L) in medium quality water so as to ensure the safety of drinking water.
The accurate assessment of large-scale and complex coastal waters is a grand challenge due to the spatial nonstationarity and complex nonlinearity involved in integrating remote sensing and in situ ...data. We developed a water quality assessment method based on a newly proposed geographically neural network weighted regression (GNNWR) model to address that challenge and obtained a highly accurate and realistic water quality distribution on the basis of the comprehensive index of Chinese Water Quality Classification Standards. Using geostationary ocean color imager (GOCI) data and observations from 1240 water quality sampling sites, we conducted experiments for a typical large-scale coastal area of the Zhejiang Coastal Sea (ZCS), People’s Republic of China. The GNNWR model achieved higher prediction performance (average R 2 = 84%) in comparison to the widely used models, and the obtained water quality classification (WQC) maps in May of 2015–2017 and August 2015 can depict intuitively reasonable spatiotemporal patterns of water quality in the ZCS. Furthermore, an analysis of WQC maps successfully illustrated how terrestrial discharges, anthropogenic activities, and seasonal changes influenced the coastal environment in the ZCS. Finally, we identified essential regions and provided targeted regulatory interventions for them to facilitate the management and restoration of large-scale and complex coastal environments.
Remotely sensed hyperspectral data can support more effective water quality monitoring. Nevertheless, the variability and complexity of urban river water make it hard to retrieve comprehensive water ...quality characteristics directly, so that most current water quality assessments rely on semiempirical, semianalytical, or bio-optical approaches. In this study, we carried out simultaneous in situ hyperspectral data and water quality measurements. We used the 382 hyperspectral data from urban rivers of Zhongshan City in the Pearl River Delta to test how well the random forest (RF) and one-dimensional convolutional neural networks (1D-CNNs) algorithms retrieved the newly established water quality index (WQI). The RF algorithm also identified essential wavelengths for retrieving the WQI. Our results demonstrate that the RF and 1D-CNN algorithms performed well in WQI estimations. The 1D-CNN model performed significantly better than the RF model, especially on high WQI samples. Both models were insensitive to smoothing of the hyperspectral data, showing that the noise of the original hyperspectral reflectance data has a limited impact on the algorithms. In addition, when we used the essential wavelength data (mainly located between 580-590 nm and near 722, 751, 821, and 830 nm) as input data, we achieved better retrieval results. The 1D-CNN model performed the best with an <inline-formula> <tex-math notation="LaTeX">R^{2} </tex-math></inline-formula> of 0.87, RMSE of 0.574, and RPIQ of 3.082 when we used the top tenth percentile of the essential wavelength data. This study demonstrates the potential of the 1D-CNN algorithm for hyperspectral data analysis to retrieve comprehensive water quality.
This study was carried out to delineate the occurrence and spatial distribution of groundwater fluoride in a loess area of China and to determine the geochemical and anthropogenic factors that ...influence its concentration. Water quality was assessed for drinking purpose by comparing with the national and WHO drinking water guidelines, and the impacts of fluoride on human health were also quantified using the health risk assessment model recommended by the USEPA. The results demonstrate that groundwater in the study area is slightly alkaline in nature, and its quality is generally good except slightly excessive TDS, TH, Na
+
, F
−
, and nitrate at some local locations. High-fluoride groundwater is mainly distributed in the southeast part of the study area, which is in accordance with the groundwater flow direction in this area. Groundwater fluoride is mainly of natural origin and is dominantly controlled by natural factors such as pH, specific hydrochemical environment, ion exchange, and saturation state of minerals. Fluoride contributes the most to the total health risk in the present study. Children are at higher health risk than adults in this area. Establishing central water supply system and rainwater harvesting system are suggested to guarantee safe drinking water supply in this area.
Urban surface water is an important freshwater resource, and the surface water environment is increasingly being destroyed. Dynamic monitoring of surface water is of great significance for protecting ...the ecological environment. Remote sensing technology provides technical support for surface water monitoring, which overcomes the drawbacks of traditional manual sampling. It has been widely applied in surface water monitoring. The paper systematically reviews the research progress of remote sensing technology in surface water monitoring from the aspects of remote sensing data, inversion models and water quality parameters. Advantages and disadvantages of inversion models (analytical methods, empirical methods, semi-empirical methods, machine learning methods and comprehensive methods) are compared and analysed. Furthermore, we summarize the research progress of remote sensing technology in monitoring chlorophyll a (Chl-a), total suspended matter (TSM), coloured dissolved organic matter (CDOM), transparency and non-photosensitive parameters. Although remote sensing technology provides new ideas for surface water monitoring, there are still some problems that need to be solved, such as remote sensing signals being affected by the atmosphere, poor portability of inversion models, low resolution of satellite sensors, and susceptibility to external factors. Therefore, future research should combine multi-source data, conduct in-depth research on the optical characteristics of surface water bodies, optimize inversion methods, construct transferable inversion models, break through temporal and spatial limitations, and promote the rapid development of surface water pollution monitoring and warning.
The water quality of Himalayan rivers and streams is deteriorating due to multitude of anthropogenic and natural influences and the changes are more pronounced in smaller hill basins with high human ...influx. Inadequate data and lack of monitoring further exacerbate the situation. The surface water quality of one such hill stream, Neeru was evaluated for potability and irrigation quality. The water quality parameters were analysed at 25 sampling stations over a stretch of 30 km across four seasons during a 2-year study from January 2014 to December 2015. The CCME Water Quality Index (WQI) indicated excellent water quality in upstream stations, while the midstream and a few downstream stations revealed varying degrees of impaired water quality. Although the irrigation quality of the stream was excellent, pollution levels near urban areas were rather high, necessitating considerable treatment for human consumption. The factor analysis yielded seven components with Eigenvalues greater than one that accounted for 83.656% of the variance and enabled the grouping of selected parameters based on comparable characteristics. The hydrogeochemical characteristics of the water samples indicated that they lie within the zone of rock dominance, while the trilinear diagram depicted the Ca-bicarbonate rich stream water. The study concluded that the upstream stations revealed pristine water quality, which significantly degraded towards human settlements. It thus calls for regular and long-term monitoring of the surface water quality to ensure the continuous and sustainable use of this important water body.
Numerous indicator models have been developed and utilized for the assessment of pollution levels in water resources. In the present study, modified water quality index (MWQI), integrated water ...quality index (IWQI), and entropy-weighted water quality index (EWQI) were integrated with statistical analysis for the assessment of drinking water quality in Umunya suburban district, Nigeria. There is no known study that has simultaneously compared their performances in water quality research. Overall, the results of this study showed that the water supplies are threatened by heavy metal pollution. The parametric quality rating analysis observed that Pb contamination has the most significant impact on the water supplies. Hierarchical cluster analysis was proved very efficient in the allotment of the possible sources of pollution in the study area. MWQI results classified the water supplies as “marginal”, signifying that they are frequently threatened. Based on the IWQI, 26.67% of the samples are suitable for drinking, 13.33% are acceptable for domestic uses, and 60% are unfit for drinking purposes. Similarly, the EWQI results showed that 60% of the samples are unfit for human consumption, whereas 40% are suitable. Investigation into the performance and sensitivity of the MWQI, IWQI and EWQI models in water quality assessment was analyzed and the results showed that they are all sensitive, efficient and effective tools. This study has indicated that the integration of the three models gives a better understanding of water quality. The excessive concentration of some potentially toxic heavy metals in the water supplies suggests that the contaminated water supplies should be treated before use.
Ensuring safe water supply for communities across the United States is a growing challenge in the face of aging infrastructure, impaired source water, and strained community finances. In the ...aftermath of the Flint lead crisis, there is an urgent need to assess the current state of US drinking water. However, no nationwide assessment has yet been conducted on trends in drinking water quality violations across several decades. Efforts to reduce violations are of national concern given that, in 2015, nearly 21 million people relied on community water systems that violated health-based quality standards. In this paper, we evaluate spatial and temporal patterns in health-related violations of the Safe Drinking Water Act using a panel dataset of 17,900 community water systems over the period 1982–2015. We also identify vulnerability factors of communities and water systems through probit regression. Increasing time trends and violation hot spots are detected in several states, particularly in the Southwest region. Repeat violations are prevalent in locations of violation hot spots, indicating that water systems in these regions struggle with recurring issues. In terms of vulnerability factors, we find that violation incidence in rural areas is substantially higher than in urbanized areas. Meanwhile, private ownership and purchased water source are associated with compliance. These findings indicate the types of underperforming systems that might benefit from assistance in achieving consistent compliance. We discuss why certain violations might be clustered in some regions and strategies for improving national drinking water quality.
PDF