The purpose of this paper was to assess the quality of groundwater in Behshahr (Iran) based on water quality index (WQI). Sixteen water samples from this coastal aquifer were collected and analyzed to study physico-chemical parameters such as pH, hardness, chloride (Cl), electrical conductivity (EC) and total dissolved solids (TDS). The results showed that the annual average of TDS value increased by 343 mg/l between 1999 and 2015 due to anthropogenic activities. According to WQI, it was concluded that the groundwater quality degraded over the last sixteen-year period so that the percentage of samples identified as "good water" decreased by 18.5% and on the other hand, alas, the percentage of "poor water" quality soared by nearly 12.5%. Correspondence of WQI distribution diagram with that of chloride-bicarbonate ratio attests to the significant contribution of saltwater intrusion to groundwater quality deterioration in this area.

The purpose of this study was to analyze the quality and quantity of groundwater in Sharif Abad Basin, located in Central Iran. The analysis of data collected from 24 observation wells indicated that the mean water table has plummeted about 0.896 m/year during 19 years between 1993 and 2013 due to illegal groundwater pumping, which is the main cause of groundwater quality deterioration in this area. Seventeen samples were collected and analyzed to study physicochemical characteristics of groundwater such as pH, Hardness, Chloride (Cl), Electrical Conductivity (EC) and Total Dissolved Solids (TDS) values. The results were compared to drinking water quality standard published by World Health Organization (WHO) and it was concluded that none of the water samples was potable. The spatial distribution of anions and cations followed an increasing pattern eastwards towards the Salt Lake. The analysis of Hydrochemical facies of groundwater using Piper diagram indicated that the major type of groundwater in this basin is Na-Cl, which is mainly different from common type of fresh water in Iran (Ca-HCO 3 ). Suitability of groundwater for irrigation purpose was assessed using Wilcox diagram and it was shown that all the water samples in 2013 belonged to C4S4 category, meaning they were not suitable for irrigation either. According to the ratio of chloride-bicarbonate, 100% of the samples were contaminated by saltwater intrusion. Also, the sodium-chloride ratio indicated that almost 60% of samples were contaminated by Halite solution. The presence of this solution proves the presence of salt domes in this area.

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