Wilcox Diagram Research Articles

Hydrochemical characteristics and water quality evaluation of shallow groundwater in Suxian mining area, Huaibei coalfield, China

The aim of this study is to evaluate the hydrogeochemical characteristics and water environmental quality of shallow groundwater in the Suxian mining area of Huaibei coalfield, China. The natural formation process of shallow groundwater in Suxian is explored using Piper trilinear charts and Gibbs diagrams, and by examining the ratios between the major ions. United States Salinity Laboratory (USSL) charts, Wilcox diagrams, and the water quality index (WQI) are further employed to quantify the differences in water quality. The results reveal that the main hydrochemical facies of groundwater are HCO3–Ca, and that silicate dissolution is the main factor controlling the ion content in shallow groundwater. The USSL charts and Wilcox diagrams show that most of the water samples would be acceptable for use in irrigation systems. The WQI results for each water sample are compared and analyzed, and the quality of groundwater samples around collapse ponds is found to be relatively poor.

Evaluation of River Chenab water quality with respect to its users, using different classification schemes

Abstract The Chenab River has always offered a cradle for civilizations in Punjab province of Pakistan; however, in recent times, the quality of this river has been gradually degraded due to several point and non-point pollution sources being introduced in its water. The riverine water quality was evaluated to check the suitability of water for drinking, livestock and irrigation purposes. Water samples (n = 54) were collected across the river, over a period of three years (2012–2014) and subjected to physicochemical analysis. Water quality index rating revealed that the water of River Chenab fell under the marginal category for drinking and livestock watering, due to the presence of heavy metals pollution above safe limits. Irrigation suitability parameters, such as the sodium absorption ratio (SAR), residual sodium carbonate (RSC), Na (%), Kelley's ratio (KR), magnesium hazard (MH) and the permeability index (PI) were measured, and most of the samples were within the safe limit. The piper classification of hydro-chemical parameters revealed that the alkaline-earth metals and strong acids exceed the alkali metals and weak acids, respectively. A Wilcox diagram indicated the alkali hazard was low while salinity hazard has an increasing trend. Spatiotemporal distribution of the pollutants highlighted minimal pollution until Qadirabad site (S4) which gradually keeps worsening at the downstream sites. Two factors of water quality deterioration were identified as pollution addition from the point and nonpoint sources, and diversion of the water through canals. It is inevitable to manage water quality of the Chenab River by reducing point sources pollution, through law enforcement.

Chemical Characteristics of the Karmanasha River Water and Its Appropriateness for Irrigational Usage

Water is a prime natural resource and precious national asset and one of the chief constituents of the environment. The chemical characteristics play a key role in terms of ecological and economic perspectives in the river water. The characterization and evaluation of river water quality in the Karmanasha River is necessary due to its immense importance in the livelihood of the people in the core urban areas of Kathmandu valley, Nepal. In this study, the surface water samples were collected from 16 sites with a 0.5 km interval to characterize and evaluate the water quality mainly from the perspective of its irrigational usage. The assessment was carried out by applying electrical conductivity (EC), sodium percentage (Na%), sodium adsorption ratio (SAR), permeability index (PI), Kelly’s ratio (KR), magnesium adsorption ratio (MAR), cation ratio of soil structural stability (CROSS), Wilcox diagram and water quality index (WQI) including the general hydrochemistry. The general hydrochemistry of river water indicates slightly alkaline in nature with mean pH value 8.07, and the dominance order of major ions follows the pattern of Ca2+>Mg2+>Na+>K+ for cations, and HCO3->Cl->NO3- for anions. Furthermore, the results revealed that the water is safe for irrigation purposes based on EC, Na%, SAR, KR, MAR, CROSS, and Wilcox diagram. The results also specified that no severe degradation in water, however, the low DO, and high BOD and COD values than that of the standard value prescribed by Nepal Drinking Water Quality Standard, signify the anthropogenic signature in the river water. This study provides the baseline information about the WQI and suitability of irrigation water quality, and further in-depth studies are required at spatiotemporal levels to get in-depth insights about the ecological health of the river.

HYDROCHEMICAL EVALUATION OF THE AZRAQ UNCONFINED AQUIFER, JORDAN

The groundwater hydrochemical characteristics of the Azraq Basin were investigated and evaluated statistically. The presence of an underground saline water body in the Qa’ Al-Azraq area has made this specific part of the basin.  38 samples from 38 GW wells were collected to understand the GW hydrochemistry of the Azraq unconfined aquifer that is mainly composed of marl, evaporites, limestone and clay formations. The PCA analysis indicates that Na, Mg, Cl, Ca, and K contribute the variance in the chemical composition of the GW samples. Piper, Durov and Wilcox diagrams indicated that the water types are mainly earth alkaline with prevailing SO4 and Cl, and alkaline water with prevailing SO4 and Cl. The main processes in the basin are dissolution or mixing and reverse ion exchange in which Na and Cl are prevailing. The GW is mainly oversaturated concerning aragonite, calcite and dolomite as indicated by the excess input of Mg and Ca ions from the rock-water interactions, while anhydrite (CaSO4), halite (NaCl), and gypsum (CaSO4.2H2O) are generally undersaturated. The effect of the agricultural activities in the study area is reflected by the positive correlation between NO3 and PC2. Wilcox diagram indicates that the samples are in the medium to very high salinity slots with the majority in the high salinity slot and in the low and medium alkali hazard zone, while few samples show high to very high alkali hazards. The simulated salinity for the next 30 years shows alarming danger and requires immediate attention as the Qa’ area is expected to become saline with TDS values of 2500 to 4600 mg/l, unsuitable to use for domestic and/or agricultural purposes.  

Impact assessment of faecal sludge on groundwater and river water quality in Lucknow environs, Uttar Pradesh, India

The present study aims at Faecal Sludge (FS) characterization and assessing water quality impacted due to waste dumping in one of the India's most polluted cities, Lucknow. In order to accomplish the objective; FS, groundwater and river water were sampled from the study area in the post monsoon season.Ground water and river water data were assessed by using Piper diagram, Gibbs' diagram, Water Quality Index (WQI), Wilcox's diagram, US Salinity Laboratory's(USSL) diagram and multivariate statistical analysis.The study reveals that FS sample contains considerable amounts of electrical conductivity, cations and anions.Piper diagram demonstrates that dominance of the anions is mainly HCO3in groundwater and river water. Whereas, Gibbs' diagram depicts that the chief source of soluble ions is weathering of rocks over which water flows. The ground water samples were grouped into excellent, good and poor while river water samples were grouped as good, poor, very poor and unsuitable for drinking as per WQI. Wilcox and USSL diagram indicated the majority of the samples are suitable for irrigation in groundwater and river water. Major Principal Components (PCs) have been identified by principal component analysis for groundwater and river water that explained 76% and 85% of the total variance in the dataset, respectively.PC1, PC2, PC3 and PC4 reflect the weathering, weathering along with anthropogenic, geochemical and anthropogenic component in groundwater, respectively. While for river water, PC1, PC2 and PC3 indicate mineral, anthropogenic and hardness component, respectively. Hierarchical cluster analysis depicts three types of cluster for groundwater and two types of cluster for river water samples based on the similarities in chemical composition. The study signifies that open dumping of waste is influencing the groundwater quality in solid waste disposal &slum area while pollution load of river water in downstream is increasing due to discharge of effluent.

Assessment of groundwater quality for drinking and irrigation uses in taluka Ratodero, district Larkana, Sindh, Pakistan

ABSTRACT The study was carried out to examine the different water quality parameters for groundwater of taluka Ratodero, district Larkana, Sindh, Pakistan. The samples from hand pumps were collected from 25 different locations during October 2019. The parameters like Electrical conductivity (EC), total dissolved solids (TDS), pH, total hardness, Cl, alkalinity, SO4, Na, Mg, K, Ca, Fe, Zn, Pb, Cd, Ni, Cr, Cu, Mn, Co, As and fluoride were examined. The groundwater was also tested for suitability for irrigation based on sodium adsorption ratio, Kelly's index, permeability index, sodium percentage (Na%), salinity hazard and Wilcox diagram. The samples were also examined for water quality index (WQI) and contamination index. The statistical analyses were carried out by calculating cluster analysis, correlation coefficient and hydrochemical facies between different parameters to evaluate the water quality. The results of physico-chemical parameters were compared with World Health Organization guideline. Twelve samples (48%) were not suitable for drinking on the basis of EC and TDS, and results of chloride and fluoride of 36% samples were not fit for drinking purposes and 9 (36%) samples were of poor quality based on WQI, contaminated index (Cd), Pb, Ni and Cd. The chronic daily intake indices and hazard quotient indices were calculated, and results showed that Ratodero city groundwater was of concern for human health. The treatment methods are recommended for unsuitable groundwater samples for drinking purpose. The results of water quality for irrigation indicated that 60–80% of the samples were suitable for irrigation.

Impact assessment of coal mining on groundwater chemistry and its quality from Brajrajnagar coal mining area using indexing models

Groundwater chemistry and quality studies have been carried out in the Brajrajnagar coal mining area to find its suitability for human consumption, domestic use, agriculture use as well as industrial purposes. A total of fifty-four water samples were collected in Polyethelene containers from several surface and groundwater sources during the summer month of May, 2015. Physical parameters like pH, electrical conductivity (EC), total dissolved solids (TDS) and temperature were measured in situ. Major ions (Na+, K+, Ca2+, Mg2+, SO42− NO3−, Cl−, F− and HCO3−) and trace elements (B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Ba and Pb) were analysed in the laboratory. Hydrogeochemical facies present in the groundwater have been identified. On the basis of water chemistry, water quality index (WQI), heavy metal pollution index (HPI), and heavy metal evaluation index (HEI) were determined to ascertain the overall quality of the water for drinking purposes. Suitability of the water for the agricultural purposes was also determined using sodium percentage (Na%), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), US salinity diagram, Wilcox's diagram, Kelly's ratio (KR) and permeability index (PI). The overall groundwater quality studies show that 15% samples are poor in quality for drinking purposes and 43% water samples require special treatment prior to irrigation. The present work will help the local government bodies and mining planners to understand the spatial variation of the quality of groundwater of the Brajrajnagar coal mining area. It will also help to know about the degradation in the water quality and its possible sources and to adopt appropriate monitoring programmes and strategies for protection of the water resources of the region.

Countrywide Groundwater Quality Trend and Suitability for Use in Key Sectors of Korea

Under changing climate, increasing groundwater use has risen the concern for groundwater quality variations over recent years, to maintain a healthy ecosystem. The objectives were to identify trend of temporal variations in groundwater quality and its suitability for different uses in Republic of Korea. Water quality data were collected from 198 monitoring stations of Groundwater Quality Monitoring Network (GQMN), annually for the period of ten years (2008–2017). Non-parametric trend analysis of a Mann–Kendall test and Theil–Sen’s slope was done on groundwater physico-chemical data of ten years. Groundwater suitability evaluation was done for use in main sectors including domestic (drinking) and agriculture (irrigation). For drinking suitability analysis, results were compared with World Health Organization (WHO) and Korean Ministry of Environment (KME) established guidelines. For irrigation suitability evaluation, electrical conductivity (EC), Sodium Adsorption Ratio (SAR), percent of Na+, Residual Sodium Carbonate (RSC), US Salinity Laboratory (USSL), and Wilcox diagram were used. Most significantly, water type belongs to Ca-HCO3 and Ca-SO4 types, but a small proportion belongs to Na-CO3 and Na-Cl types. Approximately, 96% and 93% of groundwater samples are suitable for drinking, based on WHO and KME guidelines, respectively. Around 98% and 83% of groundwater samples are in suitable range for irrigation use, based on USSL and Wilcox diagrams, respectively.

AN ASSESSMENT OF GROUNDWATER QUALITY FOR THE SUITABILITY OF IRRIGATION IN RELIZANE PLAIN, ALGERIA

Located in an area characterized by an arid climate, the plain of La Mina, records an annual rainfall of 300 mm and an evapotranspiration equal to 1500 mm, which generates a deficit of 1200 mm, this shortage of water allocated to agriculture, forced farmers to use groundwater. The soils of the plain of the Mina and in particular the soil of the irrigated perimeters, suffer from a problem of salinization. Irrigation methods and the quality of the water used are the decisive triggers. The results of the hydrochemical analyzes carried out, focused on the major elements of these waters. They mainly have a sodium chloride facies, an EC average of (5.16 dS / m) which indicates that the waters are heavily salted, an average value of (SAR) of 20.67, shows that there is a very high risk of sodicity, playing a role in the physical degradation of soils. The Riverside and Wilcox diagrams show that it is the C4S4 class which is the most dominant, corresponding to a water of very high salinity and strongly sodium of poor quality, not recommended for irrigation.

Physicochemistry and water quality of Loktak Lake water, Manipur, India

ABSTRACT A total of 32 surface water samples (pre – and post-monsoon) from different locations of Loktak Lake, Manipur, were studied for physicochemistry and water quality to assess its potability. Parameters, namely, water temperature, pH, electrical conductivity (EC), major ions (Ca2+, Mg2+, Na+, K+, HCO3ˉ, Clˉ, NO3ˉ, PO4 3ˉ and SO4 2ˉ), dissolved silica (H4SiO4) and potentially toxic elements (Fe, Mn, Cu, Zn, Ni, Cr, Co, Cd and Pb) were analysed. The water is neutral to alkaline in pre-monsoon and slightly acidic to alkaline in post-monsoon. Twenty-five percent of the post-monsoon samples have a higher pH than the WHO acceptable limit. The water is soft with low EC and total dissolved solids (TDS). The pre-monsoon samples have a relatively higher concentration in the majority of parameters studied except HCO3ˉ, SO4 2ˉ, NO3ˉ, PO4 3ˉ, dissolved organic carbon and dissolved inorganic carbon. The concentration of cations (mg/L) follows an order of Ca2+> Mg2+> Na+ > K+ and that of anions HCO3ˉ > Clˉ > NO3ˉ > PO4 3ˉ > SO4 2ˉ. The concentration of Pb in the majority of samples was above the acceptable limit for drinking. The lake water chemistry is mainly derived from rock-forming minerals besides anthropogenic sources. Carbonate weathering dominantly influences the water chemistry along with a minor contribution from silicate weathering. The main hydro-geochemical facies is Ca-Mg-HCO3. The sodium adsorption ratio, Na%, residual sodium carbonate and the Wilcox diagram indicate the suitability of Loktak water for irrigation. Based on the water quality index, the majority of pre-monsoon samples are of poor category contrary to the post-monsoon samples which are of good category. Therefore, for its potability, pre-monsoon waters from the river inlets, the national park region and the lake’s northeastern portion and post-monsoon waters from the Phubala River inlet and near the Thanga Island require pre-treatment.

The modeling and prediction of the quality of the groundwater resources in Tuyserkan plain using the optimized artificial neural network

Tuyserkan plain is an important agricultural plain located in Hamadan province, Iran. Despite the severe decline of the water levels in aquifers, the quality of the plain has not been evaluated in recent years. The present study aimed to analyze the data of 15 wells during 12 years to evaluate the quality of groundwater in this area using the Wilcox diagram for the aquifer. The electrical conductivity (EC) of the plain was interpolated using the Kriging method to evaluate its spatial distribution since this parameter has caused a decline in the quality of the groundwater in the plain. According to the findings, the EC value was higher in the eastern parts of the plain and Tuyserkan city, which was described as the spatial distribution of the parameter. The Pearson's correlation-coefficient was used to assess the correlations between EC and other parameters. To predict and model the EC value, multi-layer perceptron artificial neural network (MLP-ANN) were used. According to the results of the Pearson's correlation-coefficient, the reduced number of the data led to the decreased expenditures of the experiments in obtaining the input data. The third model was finally obtained with the lowest number of the input parameters, low error, and high correlations between the predicted and actual data. In this model, two input parameters and five neurons were obtained in a hidden layer (R: 0.997, mean: 8.634, NRMSE: 0.05) using the momentum and hyperbolic tangent functions, indicating the high potential of MLP-ANNs in the prediction and modeling of groundwater quality.

Irrigation Suitability Assessment of Groundwater in an Open Mining Area in Grassland Area

In this paper, the investigation of groundwater in open-pit coal mine in grassland was carried out. The hydrochemical parameters of groundwater were detected. The chemical types of the groundwater were analyzed. The temporal variation characteristics of groundwater parameters were studied, and the suitability of the irrigation water quality was analyzed. The results showed that the main hydrochemical types of groundwater were SO4 2-•Cl--Na+•Mg2+ and SO4 2-•Cl--Na+•Mg2+(Ca2+). USSL analysis showed that most of the groundwater samples in the study area belonged to the type of high salinization and low alkali damage. Wilcox diagram analysis showed that most of the groundwater was in good and usable water quality area, and no groundwater sample was in unusable area. The results of single factor index SAR, %Na, RSC and PI analysis showed that most of groundwater was suitable for irrigation. Therefore, the groundwater in the study area was generally suitable for irrigation in pastoral areas. This study is of great significance to the rational development and utilization of groundwater resources.

Groundwater quality and associated human health risk assessment in parts of Raebareli district, Uttar Pradesh, India

Groundwater is a primary drinking water source in various parts of Indo-Gangetic plain. Many rural agglomerations in this alluvial plain face scarcity of safe drinking water. Yet, there is a lack of public awareness and scientific studies in these areas, and Raebareli district is one of them. Groundwater samples collected from handpumps, dugwells, and tubewells were analysed for various physico-chemical parameters and compared with drinking standards for drinking suitability. The elevated concentrations of nitrate can be attributed towards heavy fertilizer application and irrigation practices, whereas rock-water interaction can be a cause for higher fluoride concentrations in groundwater. The ionic abundance was in order of HCO3− > Na+ > Cl− > SO42− > Mg2+ > Ca2+ > NO3− > K+ > F−, and HCO3− > Na+ > Cl− > SO42− > Ca2+ > Mg2+ > NO3− > K+ > F− during the pre-monsoon and post-monsoon seasons respectively. Irrigation suitability of groundwater was also assessed using Sodium Absorption Ratio, Wilcox diagram, Doneen's plot, Kelley's index, Magnesium Hazard, and other suitable indices. The analysis suggested that there is a medium to high salinity hazard in the area. As per Kelley's index, approximately 57% of the samples were found unsuitable for irrigation practices. Non-carcinogenic health hazards associated with nitrate and fluoride and their impacts on adult men and children were also assessed. The ‘Total Hazard Index’ values ranged from 0.4 to 14.5 in children, and 0.3 to 10.8 in adult men. The results also suggested that more than 82% of the samples for children and 77% for adult men could possibly impart non-carcinogenic health hazards.

Percolation pond with recharge shaft as a method of managed aquifer recharge for improving the groundwater quality in the saline coastal aquifer

The deterioration of groundwater quality has become a serious problem for the safe drinking water supply in many parts of the world. Along coastal aquifers, the saline water moves landward due to several reasons even though significant rainfall is available. The objective of the present study is to investigate the impact of a combined recharge structure including a percolation pond and a recharge shaft in improving the groundwater quality of the surrounding area. The area chosen for this study is Andarmadam, Thiruvallur district of Tamil Nadu. As a part of the study, a suitable site was selected for the construction of a percolation pond based on preliminary field investigations in 2012. Three piezometers were also constructed near the percolation pond to investigate the impact of the structure on groundwater recharge. Further, a recharge shaft was added to this structure in 2013 to overcome the clogging issues at the pond bottom and to enhance the recharge. The impact of the percolation pond on groundwater was assessed by comparing the periodical groundwater level fluctuations with rainfall in the area. The fluctuations in groundwater level near the percolation pond show variations before and after the construction of recharge shaft. The amount of water recharged through the percolation pond during the water year 2012–2013 was estimated as 250–300 m3. The volume of recharge was calculated to be increased more than twice after the construction of recharge shaft inside the percolation pond, on the assumption that recharge through the pond surface remained almost same as before. The dilution of ionic concentration in water was three times higher after the construction of recharge shaft. The long-term groundwater quality in the surrounding area of the pond improves gradually with time. The total dissolved solids (TDS) decrease considerably with time due to the dilution of dissolved solids in water with the fresh water recharging into the aquifer. The Wilcox diagram of most of the water samples after the construction of the recharge structure fall in the excellent to good category, indicating improvement in irrigation water quality.

Hazar Gölü Havzasında (Elazığ, Türkiye) Sulama Suyu Kullanımı için Su Kalite Değerlendirmesi

The goal of this work was to research the suitability of water sources for agricultural use in the Lake Hazar Basin For this purpose, samples are taken from 61 locations during the wet period and 60 locations during the dry period in 2015 and analyzed pH, electrical conductivity, calcium, magnesium, sodium, potassium, bicarbonate, chloride and sulfate parameters. Based on these analyses sodium percentage (Na%), sodium absorption ratio (SAR), residual sodium carbonate (RSC), magnesium ratio (MR), permeability index (PI) and Kelly’s ratio (KR) were calculated. Also, the usability of groundwater in agricultural activities is evaluated according to Wilcox and United States Salinity Laboratory (USSL) Diagrams. The EC, SAR, Na%, RSC, PI, KR and MR values revealed that suitability of waters as irrigation water, except for a few locations close to the lake. Similar results were obtained from classifications made according to USLL and Wilcox diagrams. The thematic maps of water quality parameters displayed that the groundwater quality decreases along the flow path from high elevations to lake level.

Evaluation of Irrigation Water Quality by Data Envelopment Analysis and Analytic Hierarchy Process-Based Water Quality Indices: the Case of Aksaray City, Turkey

In this study, two water quality indices (AHP-IWQI and DEA-IWQI) based on Data Envelopment Analysis and Analytic Hierarchy Process have been produced in order to evaluate the water quality of surface waters used in agricultural irrigation. Depending on the efficiency scores of indices, two different water quality classification systems, which are composed of four suitability categories, have been defined. The 10 different alternatives and a total of 13 sub-criteria classified under 3 main criteria groups were used in the establishment of a hierarchical structure. For the sub-criteria, efficiency scores for electrical conductivity and sodium adsorption ratio having the highest efficiency score were calculated as 0.214 and 0.148, respectively. The results obtained from the indexes were compared with the results of the United States Salinity Laboratory and Wilcox diagrams. The comparative results of the predictions by AHP- and DEA-based indexes show that the accuracy ratio of the DEA-IWQI is higher than of the AHP-IWQI.

Source rock weathering and groundwater suitability for irrigation in Purna alluvial basin, Maharashtra, central India

Purna alluvial basin is characterized by low to high level groundwater salinity having adverse effect in a large area, however, the basin still lacks one-time data of any season regarding hydrogeochemistry and quality assessment for drinking and irrigation purposes. The present work is aimed to determine various weathering indices and estimation of groundwater quality for irrigation purpose. The interpretations are based on the study of total 158 samples, collected from dug wells (60) and bore wells (98) during both pre- and post-monsoon periods of the year 2009. The plots between Ca+Mg vs. SO4+HCO3, Na vs. Cl and Na vs. HCO3 reveal that most of the samples fall below the equiline that indicates prevalence of silicate weathering. The USSL diagram (Wilcox diagram) demonstrates higher concentration of points in the fields of C2S1 and C3S1 for both the aquifers, indicating high salinity and low to medium sodium water; however, a few sample points positioned in C3S4 and C4S4 fields indicate high salinity but medium to high sodium. The values of Na%, RSC, Kelley ratio and magnesium ratio for most of samples exhibit doubtful to unsuitable categories of groundwater for irrigation from both the aquifers during pre- and post-monsoon periods. The vast data bank generated for entire basin is significant for government and non-government organizations for future planning and management.

Temporal Variation of Tropical Karst Groundwater Suitability for Irrigation in Gremeng Resurgence, Gunungsewu Karst Area, Indonesia

Analysis of groundwater availability for irrigation purposes pertains to not only quantity but also quality. The characteristics of groundwater quality essentially define crop productivity and determine whether or not crops can grow. This research was designed to identify the suitability of karst groundwater for irrigation temporally (in one year), with an example of Gremeng Resurgence in Gunungsewu Karst Region, Indonesia. It drew on data on electrical conductivity and several major ions, such as potassium, magnesium, sodium, and calcium, by analyzing % sodium content (Na%), Sodium Adsorption Ratio (SAR), and groundwater suitability for irrigation using the Wilcox and USSL diagrams. These analyses revealed that the water quality observed varied by seasons owing to the effects of dilution by rain and water-rock interaction in the karst region. However, this temporal variation was not substantial so that the classes of groundwater suitability only ranged between good and excellent, and the salinity hazard levels differentiated into low until medium.

Water quality and land use/cover changes in the Phewa Watershed, Gandaki Province, Nepal

Knowledge and understanding of land use and water quality nexus is an important precursor for assessing the human-water interactions and sustainable freshwater management. In this study, the land use/cover change (LUCC) and water quality assessment with respect to drinking and irrigational purposes were carried out in Phewa Lake, Nepal. A total of 20 water samples were collected during the winter and summer seasons in 2017 and were analysed for major hydrochemical variables. The water quality index of Phewa Lake was found to be 5.15 and 2.57 during the winter and summer, respectively, indicating the suitability of water for drinking purposes. The results revealed that the electrical conductivity, sodium percentage, and sodium adsorption ratio were found to be 38.80 µS/cm, 16.99, and 0.10, respectively in the summer and 85.06 µS/cm, 14.68, and 0.15, respectively in the winter. Similarly, permeability index, Kelly’s ratio, magnesium hazard, cation ratio of soil structural stability, and Wilcox diagram exhibited that the water was suitable for irrigation in both seasons with relatively better quality in the summer. The dynamic pattern of LUCC in the Phewa watershed exhibited an increase in the spatial extent of forest, shrub-land, grassland, and built-up area, whereas decreasing trend of agricultural land, barren land, and water bodies. Irrespective of the seasonality, the LUCC-water quality nexus showed elevated concentrations in the proximity of the urban settlements. The present study could be helpful for the restoration of water quality by sustainable land-use practices in the Himalayan region.

Impacts of drought phenomenon on the chemical quality of groundwater resources in the central part of Iran-application of GIS technique.

In the recent decades, global warming has caused water shortages all over the world. This study aimed to investigate the impacts of drought caused by climate change on the chemical quality of groundwater in Saveh County, Markazi province, Iran. The physicochemical parameters of 29 wells were analyzed by the Standardized Precipitation Index (SPI) during the drought period 2004-2015. Wilcox and Schoeller diagrams were applied to evaluate the water quality of wells for irrigation and drinking purposes, respectively. Schoeller diagram was consulted to show the relative concentrations of anions and cations typically expressed in milliequivalents per liter. Also, the Wilcox diagram was consulted to determine the suitability of water for agriculture purposes. Finally, the geographic information system was applied to the zoning of the groundwater quality parameters. According to the results, almost 90% of wells were in the category of "very salty and harmful for agriculture uses" in the last year of the study period (2015). The Schoeller diagram suggests that the water quality of 72.5, 10.4, 65.5, 100, 44.9, and 69% of wells were inappropriate and exceeded the Iranian National Standard level, in terms of TDS, TH, Na+، Mg2+, Cl-, and SO42- in 2015, respectively. A decrease in yearly average precipitation during the studied period has not only caused overuse of groundwater as the primary water resources but also led to a significant decline in its chemical quality.