The Simine-rud river in the central part of Hamedan district is emanated from some small rivers of Alvand northern valleys and north eastern mountains in Hamadan. This river arrives in Famenin city (south east of Hamedan) named Ghare-chay River. The main objective of this study was to evaluate the water quality of Simine-rud river for irrigation using Wilcox diagram. The experiment was carried out during July 2006 to June 2007. After identifying the rivers that flowed into Simine-rud, 13 sampling sites were selected to take monthly samples for determination of pH, EC, Ca2+, Mg2+ and Na+. Based on the averages of the results, sodium adsorption ratios (SAR) was calculated and then Wilcox diagram was used. Considering the EC and SAR values in selected stations, Simine-rud showed a gradual increase in pollution (salinity and sodicity) and decrease in water quality across the river from the top to the down. According to Wilcox diagram, water quality of the studied rivers was eralnated as good and medium classes (C1S1-C3S1) for irrigation purpose.

Background & Objectives: Monitoring and quality control of water resources are important tools to manage and protect these valuable resources. Hiroo River is the principal source of water supplies for Khalkhal and Kosar cities. The purpose of this work was to investigate water quality of Hiroo River by NSFWQI and WILCOX indices.Methods: In this descriptive cross-sectional study; pH, DO, BOD, TS, NO3, PO4, turbidity, temperature, fecal coliform, EC, Na, K, Ca, and Mg were determined. NSFWQI and WILCOX indices were applied. Data were analyzed by determining the above mentioned quality indices.Results: In the optimum situation, NSFWQI was related to S1 with the value of 74 in February 2009 indicating good water quality. Minimum value of 53 was determined for NSFWQI at S3 in August 2009 representing medium water quality.Conclusion: Water quality was good in upstream (S1) due to lack of contamination sources, however, discharging wastewater of Khalkhal and Givi cities to the river decreased water quality gradually in downstream (S2 and S4). Average of data obtained indicates that all the monitoring stations fall in C (medium) category based on NSFWQI classification.

In this study, the water quality of the Talar River was evaluated based on the National Sanitation Foundation Water Quality Index (NSFWQI), the Iranian Surface Water Quality Index (IRWQISC), and the Wilcox Diagram (WILCOX) at six different stations along the river during a hydrological year from October 2022 to September 2023. Subsequently, statistical analyses, including a correlation matrix and a dendrogram diagram, were utilized to study the relationships among various water quality parameters. In autumn, the poorest water quality based on the IRWQISC index was observed at the fourth station, with a value of 4. 16, indicating very poor quality for the river. Additionally, the NSFWQI analysis revealed the worst water quality at the fifth station during summer, with a score of 23. 63. However, at the first station in spring, the river's water quality slightly improved due to increased rainfall during this season. According to the Wilcox Diagram, which depends solely on two parameters—Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR)—the worst result was observed at the sixth station in autumn. This result, classified as C3S2, corresponds to moderate quality for agricultural purposes. As we move downstream, it is evident that increased agricultural and urban activities contribute to a decline in water quality across all indices. Moreover, reduced rainfall in certain months significantly exacerbates this deterioration in water quality.

Determining the quality of groundwater is one of the key elements of water usage in drinking, agriculture and industry sectors. Rafsanjan plain is one of the most economical plains in the country due to the existence of pistachio orchards. Therefore, proper management and careful study of groundwater in this plain is an essential need. The present study was conducted to evaluate the groundwater quality of the Rafsanjan plain with agricultural applications. In the first stage, after selecting the effective parameters for water quality assessment, weighting was performed by Analytic Hierarchy Process (AHP) method and then the groundwater quality of the study area was determined using GIS software and bases on water quality standard provided by the University of California. According to the results of the final zoning of groundwater quality, about 1.6% of the study area has very good quality, 20% has medium quality, 52.7 has poor quality and 25.7 has very poor quality.  In addition, based on the statistical analysis of the Wilcox diagram, 1.5%, 16.2%, and 60.2% of the wells in the study area had good, medium and poor quality, respectively. Moreover, 22.1% of the wells are not included in the diagram due to very poor quality. This research revealed that a GIS-AHP-based method could analyze these kinds of data spatially and consistent results could be obtained.

Groundwater is an important source of exploitation in arid and semiarid regions. In the Azarshahr plain, due to the reduction in annual precipitation and lack of surface runoff, groundwater resources play an important role in supplying agricultural, drinking, industrial and domestic water requirements. The aim of this study was to evaluate the quality of groundwater resources in Azarshahr plain for agricultural irrigation and to analyze the EC and SAR variations by using geostatistical methods. For spatial mapping of SO4, Cl, TDS, EC and SAR, the observational data from 47 wells in this region, which were measured during the years 2003-2017, were utilized. In order to select the best interpolation method, Kriging approach with Gaussian variogram and IDW methods were used. The obtained results revealed that the Kriging with Gaussian variogram had the lowest RMSE and the highest NS values. The results of the groundwater quality classification (using Wilcox diagram) and EC/ SAR zoning showed that the groundwater quality in the Azarshahr plain is very saline (C4S1) in most of the cases, which might be linked to the higher amounts of withdrawals from the aquifer.

“Ardabil Plain” is a middle plain that is located in northern width with geographical charactristics of 38o, 04’ to 38o, 25’, and eastern length with geographical charactristics of 48o, 10’ to 48o, 37’. This plain with width of 900 kilometers with an average height of 1350 meters is surrounded by its elevated and high highlands. Great portion of the boundary which was studied is covered by Quaternary sediments (the new one and the old one), by Quaternary sediments consisting of gravel, sand, silt and clay that include the border and the center of this plain. As you move from east and south-east towards west and north- west the amount of coarse-grained alluviums and succulent decreases. In west and north-west the boundary of output of water is nominal and is not suitable for digging a well. According to results of the analysis on a sample of 35 deep well in the region in 14 phases of the time, it is observed that in eastern area, that is at enterance of aquifer the qualitity of water is suitable, but in south-west area because of vicinity with plaster components, existence of surface current and round washing and also mineral water springs (sulphate), the quality of water decreases and the type of water changed into clorine and sulphate. With respect to distribution of Schoeller more than 90% of samples are in good condition, concerning their being drinkable. According to categorization of Wilcox, more than 50% of the samples are related to class C1S1.

In this research, the goal of evaluating the accuracy of interpolation methods is the prediction of spatial distribution of some of the quality indices of groundwater in Urmia plain. At first, the water quality data of 20 wells in the years of 2001-2014 were analyzed. The Kolmogorov-Smirnov test showed that the data were not normal and therefore the conversion of the box-cox was used to normalize them. Then, using the GIS software, the best semivariogram model was fitted to the spatial structure of the data. The results showed that for water quality parameters, circular, spherical, and exponential models are the best models for semivariogram. Then, the spatial variations of parameters were studies using different interpolation methods such as Kriging and Inverse Distance Weight with power of one to three. Then, the zoning maps of qualitative parameters were drawing with the most appropriate method in the ArcGIS software. Plain aquifer was also examined considering Wilcox and Schoeller standards for agricultural and drinking purposes. The results of the Wilecox and Schoeller standard showed that 40% of the wells in the plain have brine water to use for agriculture. Also the wells above are of good quality and acceptable for drinking.

In recent decades, the quality of groundwater in most areas of Iran has become critical. In this regard, water resources management, especially groundwater resources has a great importance. The aim of existence research was to investigate the temporal and spatial process of underground water quality changes in Ardakan plain, Yazd Province for drinking and agricultural purposes, according to water quality classification systems of Wilcox and Schuler. In this paper, electrical conductivity, sodium absorption ratio (SAR), magnesium, calcium, chlorine, acidity, sulphate and sodium were measured and then interpolated and subsequently classified according to the Kriging, Wilcox and Schuler methods, respectively. The results showed that, except for the parts of the North-East, the rest of the plain have reasonably suitable quality for drinking and with the passage of time, the quality of underground water has been deteriorated. In the case of agricultural, the same setting exists and most of the pollution has been associated with the northern and Eastern parts of the area, which has been expanding over the recent decades. The main reasons of decreasing water quality, on the one hand, can be due to the over-exploitation of water resources as the result of the expansion of urban areas and industrial activities, particularly in the city of Ardakan and Meybod, dominance of traditional agriculture and extensive cultivation of pistachio trees. On the other hand, this reduction in water quality could be attributed to the recent droughts which has diminished groundwater recharge as well.

Hydro geochemistry of surface and ground waters is a useful way to identify performing reactions in aquifers and also in recognizing effective natural and anthropogenic polluting factors in these sources. In order to study surface and ground waters quality of shahid Hashemi- Nejad gas refinery region, located 35 km south of Sarakhs town, 17 water samples were collected. Parameters of pH, temperature, electrical conductivity and total dissolved solids were measured in the field, and water samples were analyzed for major anions and cations concentrations in geochemical lab. Using Piper diagram, sodium sulfate and sodium chloride type and facies were determined for the water samples. Ca2+/Mg2+ v.as Mg2+ ,Ca2+/Ca2++Mg2+ v.as SO42-/SO42-+HCO3- compound diagrams, total hardness and PCO2 proved carbonates dissolution. Na+/Na++Cl-, Ca2+/Ca2++SO42-, HCO3-/å anions, HCO3-/SiO2 , SiO2/Na++K+-Cl-, Na++K+ and SO42-+Cl- ionic ratios determined factors such as ion exchange, dissolution of Gypsum, Halite and sulfates of sodium-potassium, and weathering of carbonates and silicates as the most important effective parameters on chemical composition of water sources in this area. In Log (aCa2+/a(H+)2) and Log (aMg2+/a(H+)2) v.as Log (aNa+/a(H+)2) diagrams, which are used for specifying soluble silicate minerals in water, all water samples showed the dissolution of Kaolinite except two samples which were located at clinochlore mineral zone. Calculating saturation indices using PHREEQC software proved that Calcite and Dolomite mineral had super saturation, Halite and Anhydrite under saturation and Gypsum mineral super saturation, under saturation and equilibrium states in all samples. Schoeller and Wilcox diagrams pointed unsuitable quality for drinking and agricultural usages for these water sources. In fact, because of formations presence with high solubility that lay out in large amount of surface, water resources in this area have not suitable quality, and on the other hand shallow water level and high temperature intensify it. Based on obtained results, natural factors have major role in quality area’s water resources.