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The water quality index is very often used to classify the water quality of a river. The paper aims to develop a new improvised water quality indicator using statistical methods. To reduce the number of analysed chemical parameters and simplify the tests, WQImin was used. The results of the research conducted in Serbia in 2019 were subjected to correlation and principal component analysis (PCA). This reduced the number of parameters from 29 to 8, significantly reducing the time and cost of laboratory analyses. The temporal and spatial variability evaluation can be performed using WQImin, which consists of dissolved oxygen, total phosphorus, orthophosphate, total dissolved solids, suspended solids, chlorides, ammonium, and nitrite nitrogen. The main sources of river contamination were untreated industrial sewage, fish farming wastewater, and soil erosion. The highest level of pollution was observed in winter. Good water quality was found in the river's upper course and very good in the lower course. Water quality values obtained based on a complete and simplified set of parameters were strongly correlated with each other. [ABSTRACT FROM AUTHOR]

Amid rapid global urbanization, understanding eco-sustainability challenges in megacities like Delhi is crucial both locally and globally. This study introduces a novel multi-criteria group decision-making approach, the Z-Fuzzy Step-Wise Weight Assessment Ratio Analysis (SWARA), to address these complex challenges. This method prioritizes key eco-sustainability components like air quality index (AQI), water quality index (WQI), Temperature, and Precipitation, based on their impact, aiming to enhance resource allocation and environmental quality. Criteria weights are determined using fuzzy analytical hierarchical processing with Z-numbers, which manage decision-makers' uncertainty through a reliability function, illustrating their confidence levels and supporting the adaptability and effectiveness of eco-sustainability measures. A case study is conducted on seven sub-cities in Delhi examining their unique environmental impacts and urban sustainability challenges. Moreover, the most effective component of eco-sustainability say AQI is also dependent on some factors like PM10, PM2.5, SO 2 , O 3 , NO 2 , and CO. Considering these factors as inputs, an interval type-3 fuzzy logic system (IT3FLS) has been constructed to predict AQI, supporting timely interventions and improvements in eco-sustainability management. The IT3FLS model demonstrated exceptional precision across all Delhi sub-cities, with low root means square error (<0.05), and high R2 values (>0.94), affirming its effectiveness. To validate the Z-Fuzzy SWARA rankings, we compared them with existing Z-Fuzzy methods, consistently ranking AQI first. The IT3FLS's AQI predictions were also compared with those from fuzzy logic and advanced machine learning algorithms, demonstrating superior performance. Finally, the study underscores the managerial implications, emphasizing their role in guiding decision-making and strategy implementation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Data from state agencies provide valuable information for assessing water quality. • It is possible to evaluate water quality over time with supplemented public data. • Water quality in the Mataquito River basin has declined over the last 40 years. • Highest water quality occurs at basin outlet in winter, and Andes station in spring. The Water Quality Index (WQI) is an essential tool for monitoring trends, conducting scientific research, and making informed decisions. It offers a comprehensive view of the spatiotemporal variation in water quality in a watershed. Water quality data from various environmental assessment sources are often scattered and contain valuable information that researchers do not use. This study addresses the challenge of analyzing temporally and spatially dispersed monitoring data to assess water quality in riverine ecosystems over time. Our objective was to investigate fluctuations in water quality by constructing an aggregate water quality index, combining data from multiple public monitoring initiatives over 40 years in the Mediterranean region of central Chile, specifically in the Mataquito River Basin. Hydrochemical data were obtained from the measurement records available through the National Water Quality Monitoring Network of the Dirección General de Aguas of the Ministry of Public Works, integrating additional information from the water quality output station in the basin, which included sources from the Ministry of the Environment. Outliers for each parameter were removed and a data availability criterion was defined in relation to the total number of campaigns. Missing data were imputed to complete the matrix of water quality parameters. A total of 550 sampling campaigns provided 6624 water quality data points distributed across 10 chemical parameters and two chemical indicators, which were used to calculate the water quality index. The aggregation WQI water quality function was calculated using a modified additive method. Our research revealed that supplemented data offer valuable insights into evaluating water quality in the river ecosystems of the Andean watershed. In the lower zone, the water quality was determined to be good, while in the middle of the basin near the Andean Cordillera, it was considered acceptable. The analysis of the WQI over a decade indicated changes in water quality, irrespective of the station location in the watershed and the level of human intervention. The WQI values suggest a decrease in the water quality over the past 40 years. This study demonstrates that integrating information from diverse environmental monitoring sources into a WQI can be used to assess water quality trends and patterns in the Andean watersheds of Central Chile over time and space. These findings have significant implications for water management and decision making, providing a solid foundation for implementing appropriate strategies aimed at preserving water quality and ensuring water security in central Chile. [ABSTRACT FROM AUTHOR]

Water quality is one of the determinants of human well-being and ecosystem health. The increasing deterioration of its quality is one of the most widespread and worrisome environmental problems. In this context, the dynamics of water quality of the Cunas River in rural and urban areas in the central region of Peru during 2017–2019 was evaluated. A total of 168 water samples were collected from 56 sampling sites and nine physicochemical parameters and three heavy metals were determined. The results obtained reveal that the physicochemical parameters did not exceed the environmental quality standards for water, except BOD 5 and Fe. Cluster analysis generated three statistically significant clusters based on similar water quality characteristics and the year of study. Group 1 consisted of sectors S6 (2019) and S7 (2017–2019), group 2 consisted of S5 (2017–2019) and S6 (2017 and 2018), and group 3 consisted of S1, S2, S3 and S4 (2017–2019). The PCA generated three main factors with eigenvalues >1, explaining 76.45% of the total variance. PC1, PC2 and PC3 explained 57.6%, 10.08% and 8.70%, respectively. Water quality according to the WQI in the rural sectors was qualified as good quality water and in 67% of the urban sectors, as poor quality water. [ABSTRACT FROM AUTHOR]

Ha Long Bay is a UNESCO World Heritage Site in Vietnam with unique natural scenery. Development and socio-economic activity impact its water quality. In the context of the Vietnam National Standards, historical follow-up data taken over a five-year period (2016 to 2020), for twenty-eight widely dispersed sampling sites, has been used to carry out a temporal assessment of seawater quality utilizing a Water Quality Index (WQI) method. The analysis shows that the seawater quality is generally acceptable over this period. However, the calculated WQI values for the "pandemic year" of 2020 compared to the data for 2016 to 2019, demonstrate a significantly lesser impact for the bay overall and, more specifically, for seventeen individual sites. Ten sites remain unaffected, and one site shows a significantly higher impact. This study demonstrates how the occurrence of the pandemic in 2020 may be exploited for the interrogation of anthropogenic impacts around the bay. [Display omitted] • Seawater quality in Ha Long Bay, Vietnam, is impacted by anthropogenic activities. • Seawater quality was tracked from 2016 to 2020 using the Water Quality Index. • A lesser environmental impact for the pandemic year of 2020 was demonstrated. • The pandemic was exploited to interrogate anthropogenic impacts around the bay. • The COVID-19 pandemic allowed validation of the WQI and available data quality. [ABSTRACT FROM AUTHOR]

Groundwater in coastal areas, with surging population and growing settlements, is constantly at risk of pollution. Alappuzha is one of the most well-developed coastal districts in the southwestern Indian state of Kerala and employing various physico-chemical parameters (pH, EC, TDS, alkalinity, hardness, and contents of sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride, sulphate, nitrate, and fluoride), this study aims to evaluate the drinking and irrigation water qualities of its groundwater resources and present their spatial distributions using the GIS platform. In the moderately hard to very hard groundwater of Ca-Mg-SO4 type, the ions dominate with order Ca > Na > Mg > K and HCO 3 > Cl > SO 4 > CO 3 > F. The water quality index (WQI) values (0.85–144, avg., 26.77) established the suitability of drinking water, revealing 53 % and 45 % of samples are lies under the categories of excellent and good, respectively. Only 2 % of the sample are in extremely poor water category. SAR, RSC, Na%, PI, KR and MH indices established that almost all of the groundwater can be used for agriculture, and the samples from northern coast showed vulnerability to contamination. • Groundwater in Alappuzha district (India) contains Ca-Mg-SO4 type. • One-fifth of samples in moderately hard to very hard groundwater categories. • WQI revealing 53 % and 45 % samples under the excellent and good. • The study area groundwater more suitable for dinking and agriculture purposes. [ABSTRACT FROM AUTHOR]

Safe and reliable drinking water is one of the major prerequisites for a healthy life, as water is of fundamental importance for life on earth. Microbiological contamination is an important waterquality problem faced all over the world. Pathogen contamination of rivers that are primarily used for drinking water is an urgent consideration. For this study, seven samples were taken from different sites at different seasonal periods across four months: January, March, July, and October, all in 2019. The physico-chemical evaluation focused on the pollution of water caused by human activities. The Canadian Council of Ministries of the Environment Water Quality Index methodology (CCME WQI) was used in this study for rating the water quality index (WQI) of the Euphrates River. Physicochemical parameters including pH, temperature, nitrate ion, calcium, magnesium, total hardness, sulfate ion, chloride, total dissolved salts, electrical conductivity, alkalinity, and turbidity were determined. Water samples were analyzed for the presence of trace elements (copper and zinc). The microbiological examination included the determination of counts of bacteria Enterobacteriaceae cultivated at 36°C--37°C for 18--24 h. The results of the physico-chemical analysis and mean microbial counts of the investigated water samples were compared with the set standards (WHO guidelines for drinking water quality). Most of the physico-chemical term data indicated poor quality concerning turbidity, conductivity, and sulfate ion concentration with values much higher than the permissible standards. Water pH varied 7.6 with 574.714 ± 65.688 mg/L dissolved solids, EC (1,105.821 ± 143.986 µS/cm), tur (19.289 ± 2.845 NTU), and hardness (405.8 ± 40 mg/L) (within limit). Calcium (106.629 ± 7.244 mg/L), magnesium (43.232 ± 4.439 mg/L), and sulfate (299.964 ± 11.397 mg/L) exceeded permitted levels whereas nitrate ions were below the limit (3.564 ± 0.342 mg/L). The concentrations of trace elements, including zinc, in the current water samples were >0.01 mg/L. The bacteriological quality of most water samples analyzed in the current study did not meet the standards set for drinking water as the results showed that the count of total aerobic bacteria had reached the maximum level (114 x 10-6) cell/mL. The results of this study, therefore, show that the bacteriological data and physico-chemical parameters of the different water samples had values beyond the maximum tolerable limits recommended by the WHO for drinking water. The second part of this work focused on the spatial variability of the WQI of the Euphrates River study area, and the water samples reveal that the majority fall under marginal to poor WQI. [ABSTRACT FROM AUTHOR]

A hydrochemical study of the stream’s water in the Alaknanda basin has been carried out for the samples collected in 2016–2017 during high and low flow. The hydrochemical facies is Ca2+– HCO³ – types for most of the samples. Gibbs ratio and Cl–/[sum anion] ratio shows that the rock weathering is the primary source of solute in stream water. Apportioning of the weathering indicated that silicate, carbonate and mixed type of weathering are dominated by 52%, 19%, and 29% respectively in the watersheds. Base ion exchange index (IBI CaI1, IBII CaI2) suggested that stream chemistry is influenced by ion exchange and stream water also has deeper sources of water through joints and fissures in the watersheds. A comparison between ion concentrations in the samples suggested that few samples had magnesium and fluoride more than permissible limits. Based on dissolved ions in stream water, the water quality index indicates 80%, 14%, and 6% falls into the excellent to good, poor and unsuitable category respectively. High Kelly index and permeability index for some samples indicated the impact of rock type on water quality that may affect local agricultural productivity. [ABSTRACT FROM AUTHOR]

Sixty-five water samples were collected in July 2016 in the Mathura district and have experimentally determined the physio-chemical parameters and evaluated by comparing their values with Bureau of Indian Standards (BIS). The aim of the study is to find out the status of water quality in Mathura district. Results show that Total Hardness(TH), Total Dissolved Solids (TDS), Cl− and Mg2+ are found to be very much higher than (>50%) the permissible limit. Majority of the samples have high values NO 3 − and Cl−. The sources of Ca2+, Mg2+, Na+ and K+ are from the weathering process. In general, water chemistry is governed by complicated weathering procedure, ion exchange, impact of horticultural and sewage. CCME WQI values ranged from 1.862 to 82.254 and shows that the quality of water is good to poor. Agriculture indices like Gibbs Plot, Percent sodium (Na%), Residual Sodium Carbonate (RSC), Sodium Adsorption Ratio (SAR), Permeability Index (PI) Potential salinity and Magnesium hazard has values 0.50 to 0.99, 8.37% to 86.66%, −90.59 to 7.71 meql−1, 9.59 to 96.34, 1.82 to 21.82, 4.58 to 112.83 meql−1, and 45.57 to 8221.03 respectively. These values show that the quality of water is poor and moderately suitable for irrigation purpose. It also indicates that an anthropogenic effect on groundwater quality needs water management strategy according to their regional demand for humans. [ABSTRACT FROM AUTHOR]

• WQIs are effective water quality reporting tools. • SWOT analysis highlights the potential and limitations of indices. • A narrative review supports the application of the SWOT analysis. • CCMEWQI shows high flexibility is the most usable index. • Index application requires consistent monitoring. Water quality indices (WQIs) are well-established tools for water quality management and effective community communication. However, distinct WQIs construction processes give rise to differences in their measurability and flexibility. The present study objective was to evaluate the effectiveness of commonly used WQIs, applied to measure drinking water quality. Their benefits and limitations were discussed based on Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis. The most frequently used WQIs were the Horton (HWQI), National Sanitation Foundation (NSFWQI), Tiwari and Mishra (TMWQI), and Canadian Council of Ministers of the Environment (CCMEWQI) WQIs. The SWOT (Strength, Weakness, Opportunity, and Threat) analysis showed that the main limitations of these indices derive from their data aggregation model and from input parameter availability and selection. Among the WQIs studied, the CCMEWQI showed the highest potential and flexibility. These findings may serve as a driving force for water monitoring and surveillance systems to review their data collection and information production processes to achieve WQI full potential. [ABSTRACT FROM AUTHOR]

Abstract Our study assessed the actual water situation in the estuarine area of Lake Wuli, Meiliang Bay, Lake Taihu, China, based on eutrophication levels and status of water quality using the trophic level index (TLI) and water quality index (WQI) methods. In the wet (August 2017) and dry (March 2018) seasons, 22 estuarine areas were tested at 69 sampling sites, which included lake and rivers. Five parameters—chlorophyll a (Chl- a), total phosphorus (TP), total nitrogen (TN), Secchi disk (SD) and permanganate index (COD Mn)—were measured to calculate the TLI, and 15 parameters—temperature (T), pH, electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS), TN, TP, ammonium (NH 4 -N), nitrate (NO 3 -N), nitrite (NO 2 -N), COD Mn , calcium (Ca2+), magnesium (Mg2+), chloride (Cl−) and phosphate (PO 4 -P)—were measured to calculate the WQI. The average TLI and WQI values in the wet season were 61.69 and 60.70, respectively, and the eutrophication level and water quality status were worse than that in the dry season (TLI: 57.40, WQI: 65.74). Significant differences were observed between three parts of Lake Wuli (West, Middle and East). Regardless of wet or dry season, East Wuli had worse eutrophication levels and water quality status than the other parts, whereas West Wuli showed less severe levels. DO, TN and COD Mn used in the minimum WQI (WQI min) were the most effective parameters in our study. WQI min had stricter standards than WQI when analyzing water quality in the estuarine area of Wulihu. Factor analysis from principal component analysis (PCA) indicated that N might be the main factor affecting water quality of the most eastern sites in the wet season, and P may be the main factor in the dry season. Our results provide a valuable contribution to inform decision-making for the management of water environments by providing the actual water situation of the estuarine area of Lake Wuli. Graphical abstract Unlabelled Image Highlights • Eutrophication and status of water quality were assessed in the estuarial area of Lake Wuli. • Differences were observed between seasons and three different parts of Lake Wuli. • The wet season experienced worse eutrophication and water quality than the dry season. • East Wuli had worse eutrophication and water quality status than the other parts of the lake. • WQI min had stricter standards than WQI when analyzing water quality in this research. [ABSTRACT FROM AUTHOR]

In water quality monitoring, one of the main concerns is the increasing level of heavy metals in water resources due to human activities. This study aimed to present a framework in which, first, a new ontology-based water quality index (WQI) was developed by multi-criteria decision-making models in fuzzy environment and then, it was coupled with geographic information system (GIS) in order to model the temporal and spatial water quality changes in groundwater resources that are being supplied for drinking. The study screened for heavy metals in 45 wells in the west and northwest side of Shiraz, Iran from for a 5-year period. Six heavy metals including Pb, Zn, Hg, Cd, As, and Cr were embedded in the WQI among which the annual mean concentrations of Pb, Zn, Cd, Cr, and As increased during the research period but remained below World Health Organization (WHO) standard values in all years but, only the mean concentration of mercury exceeded the recommended WHO standard values. The methodology clearly discovered that over the time, water quality degradation has been moved from the northern part to the middle and then the southern part of Shiraz because of significant increase in heavy metals concentration which was due to the industrial development in the eastern part of the city. Groundwater quality declined over the time leading to a gradual increase in number of wells with poor water quality; however, most of them demonstrated excellent or good quality for drinking purpose. The presented framework could provide a practical pathway to portray and predict how urban development will affect the groundwater quality in future and find out its pattern. [ABSTRACT FROM AUTHOR]

The present study was conducted to examine the water quality of karst springs located along the Piedmont of Béni-Mellal Atlas (Morocco) for drinking purposes. Twenty-five water samples were collected from seven springs in June, July, August and September 2013, and May 2016 have been analyzed for their physicochemical and microbial characteristics. The analytical data of temperature, pH, DO, TAC, TH, oxidizability and NH 4 + showed that all sampled springs are suitable as drinking water according to Moroccan and the World Health Organization (WHO) standards. Nevertheless, EC, turbidity, and NO 3 − were sometimes noted higher than the allowable limits, what would be ascribed to erosion and leaching of soil and karstic rocks. The microbial analysis revealed the presence of fecal contamination (total coliforms, E. coli , and intestinal enterococci) in all springs at various times. The water quality index (WQI) calculated based on physicochemical and microbial data reveled that water quality categorization for all sampling springs was found to be ‘medium’ to ‘good’ for drinking uses in the National Sanitation Foundation WQI (NSF-WQI), and ‘‘necessary treatment becoming more extensive’’ to ‘‘purification not necessary’’ in the Dinius' Second Index (D-WQI). The Aine Asserdoune and Foum el Anceur springs showed the good quality of drinking water. According to Moroccan standards for water used for drinking purposes, the waters belong to category A1 that requires becoming drinkable a simple physical treatment and disinfection. From the type of parameters present in quantities exceeding drinking water limits, it is very obvious that these water resources are under the influence of anthropogenic activities such as sewage, waste disposal, deforestation and agricultural activities, caused land degradation and nonpoint pollution sources. Environmental attention, such as systematic quality control and adequate treatment before being used for drinking use and access to sewage sanitation, are required to guarantee sufficient protection of the studied springs. [ABSTRACT FROM AUTHOR]

Lake Taihu Basin, one of the most developed regions in China, has received considerable attention due to its severe pollution. Our study provides a clear understanding of the water quality in the rivers of Lake Taihu Basin based on basin-scale monitoring and a water quality index (WQI) method. From September 2014 to January 2016, four samplings across four seasons were conducted at 96 sites along main rivers. Fifteen parameters, including water temperature, pH, dissolved oxygen (DO), conductivity, turbidity (tur), permanganate index (COD Mn ), total nitrogen, total phosphorus, ammonium (NH 4 -N), nitrite, nitrate (NO 3 -N), calcium, magnesium, chloride, and sulfate, were measured to calculate the WQI. The average WQI value during our study period was 59.33; consequently, the water quality was considered as generally “moderate”. Significant differences in WQI values were detected among the 6 river systems, with better water quality in the Tiaoxi and Nanhe systems. The water quality presented distinct seasonal variation, with the highest WQI values in autumn, followed by spring and summer, and the lowest values in winter. The minimum WQI (WQI min ), which was developed based on a stepwise linear regression analysis, consisted of five parameters: NH 4 -N, COD Mn , NO 3 -N, DO, and tur. The model exhibited excellent performance in representing the water quality in Lake Taihu Basin, especially when weights were fully considered. Our results are beneficial for water quality management and could be used for rapid and low-cost water quality evaluation in Lake Taihu Basin. Additionally, we suggest that weights of environmental parameters should be fully considered in water quality assessments when using the WQI min method. [ABSTRACT FROM AUTHOR]

This study emphasizes hydrogeochemistry and quality degradation of groundwater in the upper Kodaganar basin, located in Dindigul district, South India. The Kodaganar basin has a particular significance and requires great attention because groundwater is the only major source for domestic and irrigation consumption. Twenty wells in the basin are randomly identified for sampling groundwater. The standard sampling procedures and laboratory experiments are followed for analyzing each sample. Index representing the suitability of drinking water is estimated based on the recommendations of Canadian Council of Ministry of Environment. The spatial distribution of the suitability was prepared by inverse distance weighted method. The traces of pollution and sources of pollution analyzed through Piper diagram suggested the role of natural and anthropogenic causes. The Gibbs boomerang diagram for both season illustrated around 85% of anions concentration dominated by rock type and also 80% of cation concentration influenced by surface interactions. This survey concludes that the overall drinking suitability of groundwater is fair in 7 wells and good in 13 wells. Only nine wells are found suitable for irrigation and rest of the wells can be used for irrigation only after minor treatment. [ABSTRACT FROM AUTHOR]

Water quality in Great Lakes coastal wetlands has been studied for decades, but few studies look at water quality changes in multiple sites over many years and relate that to land cover. In this study, water quality at 22 sites in two regions along the north shore of Lake Ontario (Bay of Quinte in the east and Durham Region in the west) was compared over a period of 12 years (2003–2014) and related to land cover data from two time periods (1999–2002 and 2009–2011) at four spatial scales; 500 m, 1000 m, 2000 m wetland buffers, and the quaternary watershed. Water Quality Index (WQI) scores significantly increased over time in both regions, and turbidity and pH both significantly decreased over time in both regions. Land cover data showed regional differences between east and west, with the western sites having higher percentage of urban land at all scales. There were significant relationships between land cover (% Natural and % Urban) and WQI score at several scales, but the relationships were strongest at the watershed scale. We found that sites in the western region showed a greater amount of change in land cover between the two time periods, compared to the eastern sites. The results of this study provide some key insights on the impact of urbanization on Great Lakes coastal wetlands, and on how they can be managed in the future. [ABSTRACT FROM AUTHOR]

The chemical characteristics of groundwater can indicate water quality condition and provide useful information for pollution source identification. This study aimed to understand the effects of dissolved organic matter (DOM) on ionic composition of groundwater and identify the main ions and sources of pollution. The Lake Taihu is a typical eutrophic lake in China. In this study, the hydrochemical composition of groundwater in the surrounding aquifer of Lake Taihu Basin was analyzed. The results showed that the values of water quality index (WQI) range from 13.29 to 56.26 (good water quality). The dominant hydrochemical type of groundwater was Ca–Mg–HCO3 type, and the rock dominance was the major mechanism controlling the groundwater chemistry. With an increasing concentration in dissolved organic carbon (DOC), the Na+, Mg2+, and HCO3– concentrations all showed a sharp increase followed by a slow increase, while the NO3– concentration showed an opposite trend, indicating the DOM can affect the ions composition. In addition, K+ was positively correlated with NO3–, As, and Cd. Hence, DOM input may directly or indirectly change the hydrochemistry of groundwater. Besides, the NO3– concentration in groundwater was much higher than that in Lake Taihu, indicating that the NO3– in groundwater mainly came from surface soil leaching. The anthropogenic sources are probably the main sources of different ions, including K+, NO3–, As, and Cd. This study can help to better understand the effects of lake eutrophication on groundwater and its pathways. [Display omitted] • Groundwater hydrochemical characteristics in Lake Taihu was explored. • DOC can affect the concentrations of Na+, Mg2+, HCO 3 − and NO 3 − in groundwater. • K+, As, and Cd were mainly derived from the application of chemical fertilizers. • Pb was mainly originated from the water–rock interactions in the aquifer. [ABSTRACT FROM AUTHOR]

The study assessed the evolution of water indicators of Remeți water body that is located in the Remeți locality in the Upper Tisa, a Natura 2000 protected area. Thus, electric conductivity, dissolved oxygen, oxygen saturation, temperature, pH, turbidity, ammonium concentration (NH 4 +), nitrates (NO 3 −), nitrites (NO 2 −), orthophosphate (PO 4 3−), dissolved Fe, Mn, water hardness, alkalinity (A) and chloride were measured over the January (I)-October (X) 2021 period. This water course was subjected to anthropic pressure, being polluted with nutrients such as ammonium and orthophosphate ions, iron and manganese. The concentrations of other metals were either low (Al, Ba, Li, Ga, Rb, Ni, Sr, Zn, Cu, Ti) or below the detection limit (Pb, Cd). The study was performed over a period of 8 months, namely January 2021–October 2021, covering the 4 seasons, in order to establish their influence on the level of water quality indicators. Exceeded turbidity values and high concentrations of ammonium, orthophosphate and dissolved iron were found, these being generally higher in the summer-autumn months. Dissolved oxygen concentrations were low in the summer-autumn months. Based on the values of the physico-chemical indicators, two types of water quality indices WA-WQI (weighted arithmetic water quality indices) and CCME-WQI (Canadian Council of Ministers of the Environment water quality indices) were calculated to evaluate the global water quality and its evolution over the seasons with a single value. WA-WQI values varied in the range of 78.56–761.63, with a tendency to increase in autumn, showing an intensified tendency of global water quality deterioration due to an increase in ammonium, turbidity, iron and orthophosphates in autumn months while CCME-WQI values were between 39.6 and 68.9, being fair in winter-spring months and marginal / bad in summer and autumn months. The results of this study are advantageous in identifying the level of pollution of Remeți water course, being a signal for local authorities in taking the necessary measures to reduce the pollution around it, for a better human health and conservation of the ecosystems hosted in the protected area. • The quality of Remeți Strem was reduced with a downward trend over the seasons. • Dissolved oxygen concentrations were low in the summer-autumn months. • The water had a high turbidity and increased concentrations of NH 4 +, Fe and PO 4 3−. • WA- WQI values increase in the summer and autumn seasons. [ABSTRACT FROM AUTHOR]

The aim of this study is evaluate water quality of the Aksu River, the main river recharging the Karacaören-1 Dam Lake and flowing approximately 145 km from Isparta province to Mediterranean. Due to plan for obtaining drinking water from the Karacaören-1 Dam Lake for Antalya Province, this study has great importance. In this study, physical and chemical analyses of water samples taken from 21 locations (in October 2011 and May 2012, two periods) through flow path of the river were investigated. The analysis results were compared with maximum permissible limit values recommended by World Health Organization and Turkish drinking water standards. The water quality for drinking purpose was evaluated using the water quality index (WQI) method. The computed WQI values are between 35.6133 and 337.5198 in the study. The prepared WQI map shows that Karacaören-1 Dam Lake generally has good water quality. However, water quality is poor and very poor in the north and south of the river basin. The effects of punctual and diffuse pollutants dominate the water quality in these regions. Furthermore, the most effective water quality parameters are COD and Mg on the determination of WQI for the present study. [ABSTRACT FROM AUTHOR]

Water quality standards of raw water resources are getting more stringent in Taiwan. This is due to the higher number of potential contaminants released to the water bodies leading to the potential risks to the human health. Raw water resources, including one river and three reservoirs representative of the major raw water resources in northern and central Taiwan, at four locations were selected to measure turbidity, electrical conductivity (EC), oxidation and reduction potential (ORP), pH, alkalinity, total organic compounds (TOC), zeta potential, particle size, Al, Fe and heavy metal contents. Natural organic matter (NOM) was also examined using high-performance size-exclusion chromatography to distinguish the different molecular weight distribution of organic compounds, such as humic acids, that might affect the subsequent raw water treatment. TOC is highly related to NOM, biochemical oxygen demand (BOD5) and chemical oxygen demand, and the influent standard is 4 mg/L in Taiwan. EC, ORP, pH, alkalinity, TOC and zeta potential had values of 231.68-350.60 µS/cm, 210.5-271.55 mV, 8.17-8.58, 65.65-86.25 mg/L, 1.54-2.73 mg/L and -16.58 to -22.60 mV, respectively. However, average turbidity (128.24 NTU) and average particle size at the Daiji River (5,067.56 nm) were higher than those at the Shimen, Yongheshan and Liyutan Reservoirs (2.20-6.39 NTU and 1,105.12-1,627.26 nm, respectively). These measured data and metal contents (the latest three years' data, at least two seasons including summer and autumn) met the regulatory standards in Taiwan. Water quality index (WQI) containing dissolved oxygen solubility, faecal coliforms, pH, BOD5, nitrates, total phosphates, temperature deviation, turbidity and total solids indicated good conditions for three reservoirs and medium condition for Daiji River. NOM, which might produce potential disinfectant by-products, had similar patterns and contained humic acids and low molecular weight acids (LMWs), with the intensity order of Yongheshan Reservoir > Shimen Reservoir > Liyutan Reservoir > Daiji River. The Carlson trophic state index and field-emission scanning electron microscope plot of filtered solid of raw water showed the potential risk of algae to drinking water safety. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating the groundwater quality within the urban reach of Gridhumal river sub-basin. 29 groundwater samples were collected with different categorization during post-monsoon (POM) and summer (SUM) seasons respectively. Various physical and chemical parameters viz., pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Total Alkalinity, cations such as, Ca 2+ , Mg 2+ , Na + , anions such as NO 3 − , SO 4 2− , F − , Cl − were analyzed and were compared with the standard guidelines recommended by WHO, ICMR, BIS. GIS techniques were used to find out the distribution of groundwater quality on land use pattern. Results indicated that the EC, TDS, TH, Na + , Cl − , NO 3 − level in groundwater samples was above critical limits, and it was found to be very high in wastewater irrigated areas in the urban reach of Gridhumal river sub-basin. Geochemical analysis of groundwater samples shows the predominance of Na-Cl and NaHCO 3 types. The geochemical data was interpreted using WQI for drinking water quality and were found not suitable for drinking purposes. With Wilcox diagram, only 30% and 21% groundwater samples show suitability for irrigation for post monsoon and summer season. The US Salinity Laboratory Staff plot depicted that all the post monsoon groundwater sources are C3-S3, C4-S4 type and C4-S4 for the summer season. 17% samples show C3-S1 type for both the season. From the HC analysis in the groundwater samples have been classified into two groups, one is ionic and another metals group. PCA results revealed the existence of seven significant principal components indicating how processes like rock-water interaction and anthropogenic activities influence groundwater quality. Seven factors which together explain 83.33% and 77.85% of the total variance in the post monsoon and summer season respectively. In comparing heavy metal contents present in water samples with BIS/WHO standards, Pb, Cr and Cd concentrations were found to be present above the maximum permissible limits and were found in the following order Cd < Pb < Fe < Cr < Mn < Zn. By results, it is concluded that groundwater is not suitable for irrigation and drinking purposes due to long term use of wastewater, anthropogenic activities, over-extraction of groundwater and changes in land use pattern. [ABSTRACT FROM AUTHOR]

Evaluation of groundwater quality and their controlling processes are very important for the sustainable utilization of groundwater in any region. In the present study, 100 groundwater samples were collected during pre-monsoon and post-monsoon 2019 from the tube well and public water supply wells in Mewat district, Haryana to investigate the water quality for drinking purposes and their controlling hydrogeochemical processes through an integrated approach. Different methods like conventional hydrogeochemical analysis, ion ratio plots, and water quality index (WQI) were applied. The results showed that the groundwater of Mewat is highly saline, with the average concentration of total dissolved solids (TDS) during the pre-monsoon (PRM) and post-monsoon (POM) being 4435 mg/L and 4938 mg/L, respectively. Statistical results revealed that anion concentrations follow the order as Cl− > SO 4 2− > HCO 3 − > NO 3 − while cation concentrations were Na+ > Ca2+ > Mg2+ > K+. The dominant hydrochemical types of Mewat groundwater were identified to be Ca2+.Mg2+- SO 4 2−.Cl− and SO 4 2−.Cl−- Na+. Silicate weathering, evaporation, and cation exchange were the three factors that control the composition of groundwater of Mewat. The chloro-Alkali indices indicate the dominance of direct base cation exchange reaction in the study area. Moreover, the results of the water quality evaluation showed that the values of WQI ranged from 72 to 3683 and 51 to 2451 during PRM and POM, respectively. WQI classes, namely Very poor and Poor water for drinking, are cumulatively represented by 64% and 58% of the total samples over the PRM and POM. And groundwater of Mewat was found mostly not suitable for drinking purposes. This is the first work in the Mewat district to assess the groundwater quality using WQI and their controlling hydrogeochemical process. This study provides insight into fundamental processes and aquifer controlling factors that are significant for the sustainable management of Mewat groundwater resources. • Pre-monsoon and post-monsoon seasons data was used to characterize the hydrochemistry and assess groundwater quality of the Mewat region. • Silicate weathering, evaporation, and cation exchange were the three factors that control the composition of groundwater of Mewat. • Groundwater from >50% area of Mewat found not suitable for drinking purposes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Appraisal of water quality index and integrated water quality index (IWQI). • Unit weight calculation based on analytical hierarchy process (APH). • Development of a "comprehensive water quality index (CWQI)" for groundwater. • Development of six distinct water classes based on CWQI. • CWQI is robust and superior to those of WQI and IWQI. The popular water quality index (WQI) and the recently developed integrated water quality index (IWQI) were used to evaluate the potability of 32 groundwater samples collected from Nalagarh valley, Himachal Pradesh, India. But their analytical results were surprisingly contrasting. While WQI classified 14 of the samples as 'excellent' and 17 as 'good', IWQI put all of them under 'unsuitable' category. This led to the development of a new index, called 'comprehensive water quality index (CWQI)', on the basis of analytical hierarchy process (AHP). Unit weights and sub-index values of both relaxable (that have both acceptable and permissible limits) and non-relaxable (that have only one guideline value) parameters were considered in the calculation process. Two segments were calculated: P CWQI (positive CWQI) and N CWQI (negative CWQI) with their scores varying between 0 and 1 and 0 and (−0.840), respectively. Grading of water quality from drinking perspective was done essentially with N CWQI scores, such as 'excellent' (when N CWQI = 0), 'good' (N CWQI = 0 to −0.21), 'marginal' (N CWQI = −0.21 to −0.42), 'poor' (N CWQI = −0.42 to −0.63), 'very poor' (N CWQI = −0.63 to −0.84) and 'unacceptable' (N CWQI = <−0.84). In fact, when N CWQI = 0, higher the P CWQI , better the water quality. When two water samples had the same N CWQI score, they were graded by their respective P CWQI score. When two water samples had the same magnitudes of P CWQI and N CWQI , they were graded equally. On the basis of this classification, groundwater in majority of the study area was classified under 'good' category for drinking purposes in absence of an alternative source of water. Compared to WQI and IWQI, CWQI proved itself to be a robust and comprehensive technique for assessing the groundwater quality. It was hence recommended to be used universally for groundwater quality assessment. [ABSTRACT FROM AUTHOR]

River Damodar situated in the South Bengal region of India is the main source of water for the surrounding industries and agricultural places. The objective of the present study is to evaluate the water quality of Damodar River in terms of an index under the influence of several physical and chemical parameters by using Canadian Council of Ministers of Environment Water Quality Index (CCME WQI) method as the river has been subjected to enormous contamination in recent times. Water samples have been procured from eight different locations along the river bank in the pre-monsoon, monsoon, and post-monsoon for the entire period of 2012. Immensely complex data were coined into a single term for the sake of convenience using CCME WQI method. This index consists of three elements: scope, frequency, and amplitude. Besides this, the seasonal variation of different water quality parameters like pH, total dissolved solid, total suspended solid, conductivity, turbidity, dissolved oxygen, chemical oxygen demand, biological oxygen demand, chloride, fluoride, chromium, alkalinity, total hardness, calcium and magnesium hardness, oil, grease, and total Coliform were also assessed during the aforementioned time period. The relationships among the eight sampling stations were emphasized by cluster analysis to characterize and evaluate CCME WQI that produces an index value in the range of 0–100 to reflect the worst and best quality water, respectively. Nevertheless, the CCME WQI values obtained from the respective stations depict fair values on an average except the last sampling station Tetul Bagan Gas Canal where the river water is heavily contaminated and thus require pre-treatment before use. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Development of an objective and rational framework (M E D -WQI) for water quality assessment that uses entropy and deviation-based approach. • Evaluation of M ED -WQI using synthetic dataset by comparing with existing Composite WQI. • Assessment of river Ganga's water quality status using M ED -WQI. In this study, a comprehensive multiplicative water quality index, M ED -WQI, for surface water quality assessment has been developed that uses sub-index functions based on deviation from maximum contaminant level of respective parameters. The parametric weights in M ED -WQI were computed using entropy based approach to eliminate subjectivity. Using a synthetic dataset the performance of M ED -WQI has been compared with Composite WQI (CWQI) that is based on Saaty's analytical hierarchical process. The results indicated that in comparison to CWQI, M ED -WQI approach provides an objective and rational framework that eliminates clustering effect in providing the water quality status. Further, M ED -WQI has been applied to an exhaustive water quality dataset of river Ganga, one of the major perennial rivers of India. Out of 224 sampling locations, 167 sites have been associated with excellent or good water quality class whereas 57 sites are identified with either fair, poor, or heavily-polluted water quality class. Furthermore, the water quality classes correlated well with the type of anthropogenic activities carried out at the site. [ABSTRACT FROM AUTHOR]

Highlights: [•] EF and I geo were used to determine metals enrichment in sediment, River Soan. [•] Cd, Zn and Pb enrichment were more in sediments. [•] RI revealed moderate ecological risk in the suspended sediment samples. [•] WQI suggests water quality was good during the pre-monsoon season. [•] Cd, Zn and Pb threats to aquatic ecosystem should not be ignored. [ABSTRACT FROM AUTHOR]

Abstract: A modified water quality index (WQI) was used to evaluate the water quality of intensive culture ponds of Litopenaeus vannamei. Multivariate statistical technique, principal component analysis (PCA), was applied to interpret the large complex water quality data set generated over a span of 120 days (from 1st July to 28th October, 2008) with weekly monitoring of 11 variables in four different shrimp ponds. The PCA revealed three, four, three, and three latent factors that accounted for 82.843%, 81.6%, 81.629%, and 84.801% of the total variance in the water quality data sets from each of the four shrimp ponds, respectively. The varifactors indicated that the variables responsible for water quality deterioration were mainly related to organic matter group (COD and BOD5), natural condition group (pH and T), and nutrient group (TAN, Chl-a and DIP) in intensive shrimp ponds. A modified WQI based on the varifactors was applied to evaluate the water quality in shrimp culture ponds. The result revealed that the overall water quality in the shrimp ponds were mainly excellent during the early period and deteriorated in the mid to late period. The WQI evaluates water quality synthetically; furthermore, it reveals the outcome when some of the other variables deteriorate significantly. Thus, this study illustrates the necessity and usefulness of multivariate statistical techniques for interpreting large and complex data sets regarding water quality in shrimp culture pond. Furthermore, the evaluation results revealed that the modified WQI can be used as a tool for determining water quality. [Copyright &y& Elsevier]

Abstract: Anthropogenic activities over the years had adversely affected the environment especially the river and its ecosystem. This paper aims to study the river quality status of Salak River (locally known as Batang Salak) and map the river based on their water classes. 18 samples were collected and tested for physical-chemical parameters (pH, temperature, DO, BOD, COD, TSS, TDS, EC and NH3-N) and heavy metals (As, Cr, Cu, Mn, Ni, Pb and Zn). Subsequently, the quality of the river is determined using Water Quality Index (WQI) and classified according to the National Water Quality Standards (NWQS) for Malaysia. The results show that the river has low level of DO (range 2.08-2.34mg/L) and high level of COD (range 645-1044mg/L), and Pb (range 0.01-0.09mg/L). Based on the WQIs and NWQS, the river quality status for Salak River falls under Class IV which indicates that the river is slightly polluted. Further actions should be taken into consideration to further improve the quality of Salak River, hence, promoting a healthier environment to the surrounding communities. [Copyright &y& Elsevier]

The lakes in Bangalore are disappearing fast and the ones that remain are on the verge of extinction. Bellandur Lake is 130 years old, situated in Varthur Hobli, towards Bangalore south of Bellandur village. The limnological monitoring study has been carried out during a year and the results reveals that the lake is highly eutrophic with low dissolved oxygen (DO) values and high concentrations of biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, phosphate and heavy metal concentrations as observed from the sludge samples. Extreme discharge of sewage and other effluents into the lake make the lake water unsuitable for drinking, bathing and the sustenance of the ecosystem as a whole. It is also attempted to identify the pollution level of the lake by employing the water quality index (WQI) method and the multivariate analysis. [ABSTRACT FROM AUTHOR]

Abstract: Intrinsic uncertainties and subjectivities of environmental problems have been increasingly dealt by using computation methods based on artificial intelligence. In order to evaluate this tool''s applicability, this study proposed the creation of a new water quality index based on fuzzy logic, the fuzzy water quality index (FWQI). The performance of the index proposed in the present work is assessed through a comparison with several water quality indices (WQIs) suggested in the literature, using data from hydrographic surveys of the Ribeira de Iguape River, in the southwestern part do São Paulo State, Brazil, from 2004 to 2006. The index was reasonably close to the other indices and showed a good correlation with the WQI traditionally calculated in Brazil. This new index may also be used as an alternative tool for decision-making in environmental management. [Copyright &y& Elsevier]

The suitability of groundwater for drinking and irrigation purposes is potentially disturbed by a variety of factors, including climate change, salinization and risky agricultural practices. The region of Kebilli (Southwestern Tunisia) is marked by an arid climatic condition with a Saharan tendency. However, the spatial partition of the stress factors was not addressed so far in spite of the increasing demand for groundwater to the agricultural and domestic activities which supports the social and economic pressure. Therefore, Water Quality Index (WQI) and Fuzzy Logic models were applied to evaluate the groundwater quality in the Kebilli region for both drinking and irrigation purposes using the geographic information system (GIS) environment to analyze the spatial partition of various factors. According to the analytical results, the calculated values of WQI are between 83.421 and 436.858 for drinking and range from 50 to 77 for irrigation purposes. The prepared Fuzzy spatial maps show that the "desirable" and "acceptable" classes of groundwater quality samples are situated in the center of the studied region, while the "undesirable" quality of groundwater is observed mainly at the Southeastern sectors due to the domestic and agricultural activities besides the over-exploitation of the aquifer. In addition, the Fuzzy membership levels generated into a GIS-based maps give a high correlation of 0.88 and 0.79 with assessed values of WQI for both drinking and irrigation purposes respectively. Grouping analyses also confirm the resulted maps, in turn, the anthropogenic effects coincides globally with the unsuitable areas for both drinking and irrigation purposes. Consequently the perturbations in the fragile environment of the oasis ecosystem are closely related to the deterioration of the groundwater quality and the intensive use of fertilizers and pesticides for agricultural needs in the Kebilli region. The research results may improve the understanding of the groundwater sustainability and as support decision makers for planning the water management and its protection. • Comparison between Fuzzy logic results and WQI gives reliable results. • Fuzzy Logic plays an important role in groundwater quality assessment. • Multi-criteria evaluation approach is powerful to assess the water suitability. • GIS integrated Fuzzy logic and WQI helps delineate appropriate water pumping areas. • The results are helpful to ensure the sustainability of groundwater management. [ABSTRACT FROM AUTHOR]

• Groundwater in the western, southern and central parts of the Sbiba plain is suitable for drinking, domestic and irrigation uses. • The deterioration of groundwater quality is linked to natural processes: water-clay interactions, dissolution and evaporation effects. • Anthropogenic pollution resulted from agricultural activities has a slight effect on WQI. • Tritium helps to define three recharge periods: from actual to 18 years, from 30 to 56 years, and older than 56 years. Hydrochemical and isotopic tracers of groundwater of the Mio-Plio-Quaternary aquifer in the Sbiba plain, central west Tunisia, are used to assess the groundwater quality for drinking and irrigation purposes as well as identifying sources of salinity variation. In this plain, the evaporation and water-rock interactions including dissolution of evaporite and carbonate minerals and cation exchange are the principal hydrochemical processes controlling the groundwater salinization and water types. Moreover, a secondary effect of salinity increase is due to the return flow of irrigation water and mixing between old and recent water within the aquifer. These phenomena are proved by the environmental isotope study. Several water quality parameters for drinking and irrigation purposes were applied. Water Quality Index (WQI) values indicate that 50 % of groundwater samples are suitable for drinking usage with "excellent" and "good" categories. According to Percent Sodium (%Na), Sodium Adsorption Ratio (SAR) and Residual Sodium Carbonate (RSC), all groundwater samples are suitable for agricultural irrigation activities. Based on the electrical conductivity (EC) and Wilcox classification, it appears that only 57 % of water samples are suitable for irrigation use; more than 50 % of these samples are "good" and "permissible". In general, groundwater in the western and central parts of the Sbiba plain is suitable for drinking and irrigation purposes. However, an attention should be accorded to groundwater salinization processes. [ABSTRACT FROM AUTHOR]

Groundwater is the primary source of fresh water for agriculture and other purposes in the Wadi El-Assiuty area; therefore, the preservation of its supply and quality is of great importance. The present study aims to evaluate the groundwater quality in the newly reclaimed parts of Wadi El-Assiuty by integrating hydrochemical data, multivariate statistical analyses, and a water quality index (WQI). In this study, 48 groundwater samples were collected and analyzed for 12 physicochemical parameters. Multivariate statistical approaches, including a correlation matrix, factor analysis, and hierarchical cluster analysis, were applied to differentiate the source of the water quality variation and determine the cause of groundwater deterioration. The factor analysis identified three main factors describing the groundwater quality in the study area, and the cluster analysis indicated two main distinct clusters of the analyzed variables. The spatial variation maps of the analyzed parameters were developed using interpolation techniques within a geographic information system environment. The WQI was applied according to the chemical drinking-water quality standards of the World Health Organization (WHO) with respect to the 12 parameters measured to evaluate the suitability of the groundwater for human consumption. The resultant WQI showed that approximately 54% of the collected groundwater samples were of an acceptable quality for human consumption with respect to the 12 parameters measured. The suitability of groundwater for irrigation was evaluated according to the salinity hazard (as electrical conductivity, EC), sodium adsorption ratio (SAR), sodium percentage (Na%), and magnesium hazard (MH). From the results, 40% of the collected samples were "permissible" for irrigation with respect to the EC, 82% were "good" to "excellent" with respect to the SAR values, 29% were "permissible" with respect to the Na%, and 90% were "suitable" with respect to the MH. • Evaluation of groundwater chemistry in Wadi El-Assiuty, Eastern desert, Egypt. • Rock-water interaction and ion exchange are governing factors in groundwater chemistry. • Multivariate statistical approaches for groundwater quality assessment. • Groundwater quality analyses for human consumption and irrigation purposes. • Suitability map for drinking purposes using a groundwater quality index technique. [ABSTRACT FROM AUTHOR]

• Uncertainty of water quality index (WQI) weights were assessed using Monte-Carlo framework. • Weights of four standards including BIS, WHO, IRISI, and ICMR were evaluated. • The ISIRI standard could not lead to accurate estimation of WQI in Iran. • Weights uncertainties in WQI parameters significantly affects the final water quality classes. • The summer uncertainties were greater than those in winter. Water Quality Index (WQI) have been recently used for evaluating water resources quality. This index is developed to assist the water resources management and their allocation for different purposes. The confidence in WQI evaluation is required for decision making. Developing WQI involves various steps that some of them have associated with the uncertainties. Uncertainties sources such as water quality sampling, measuring variability, operator biases are previously studied, whereas uncertainty associated to allocated weights of quality parameters for calculating WQI are rarely studied and seldomly evaluated. For the first time in WQI evaluations, a framework based on Monte-Carlo method is proposed to assess uncertainties associated with establishment of probabilistic weight values for WQI. Monte-Carlo simulation was used for randomly generating weights based on the posterior probability density functions (PDFs) and investigating the uncertainty throughout the computation of the WQI. Four scenarios of water quality guidelines and the weights that recommended as the functions of proposed standards in these guidelines were evaluated during dry and wet seasons. This paper studies the weight allocation uncertainty of WQI, based on application of WQI in 1189 groundwater samples of Kerman aquifer, Iran. The results showed how can provide valuable information about the confidence of WQI values. Also, the results revealed that the most variation between classes based on the applied scenarios was achieved for "excellent" and "unsuitable" classes for WQI. Therefore, application of this index in practical projects and decision making requires considerable effort for appropriate weighting of quality parameters to have reliable assessment of water resources quality. The findings of the proposed framework can support judgments on water quality conditions. [ABSTRACT FROM AUTHOR]

Hou et al. (2016) recently developed a water quality index (WQI) for assessing water quality of five typical reservoirs. Despite all the merits of the practical WQI, it suffers from lack of uncertainty consideration; a fact that motivated the present discussion focusing on mitigation of uncertainty in water quality assessment. In this regard, superiority of employing fuzzy WQI (FWQI) rather than crisp WQI is emphasized. Due to robustness of FWQI in handling uncertainties surrounding data acquisition, employment of fuzzy concept can improve water quality assessment and monitoring to generate results which are more consistent with real world conditions. [ABSTRACT FROM AUTHOR]