Assessment of groundwater quality for drinking, irrigation, and industrial purposes using water quality indices and GIS technique in Gorgan aquifer

Given the rising concern about limited access to groundwater resource, it is crucial to assess water quality. A total of 68 samples were gathered from 34 wells during 2020 in the dry and wet seasons to study the hydrogeochemical characterization of groundwater in Gorgan aquifer (Iran) using geographic information system (GIS) software. The mean values of pH, electrical conductivity, total dissolved solids, calcium, magnesium, bicarbonate, total hardness, fluoride, nitrate, sulfate, chloride, sodium and potassium were 7.42, 974.56 (µs/cm), 584.72 (mg/L), 105.56 (mg/L), 45.97 (mg/L), 296.89 (mg/L), 391.11 (mg/L), 0.33 (mg/L), 9.4 (mg/L), 89.82 (mg/L), 75.0 (mg/L), 30.55 (mg/L) and 1.79 (mg/L), respectively. The sodium adsorption ratio (SAR) varied from 1.86 to 8.66, below the allowable limits of <10 set for irrigation. Additionally, 64.71% of samples had a Langelier stability index less than zero, indicating a mild to high potential corrosivity of water. The hydrogeochemical facies of the groundwater were of Ca-Mg-CO 3 -HCO 3 and Ca-Mg-Cl-SO 4 . This study provided a clear picture from hydrogeochemical characterization of groundwater regarding the acceptability for drinking, irrigation and industrial usages. However, further monitoring is required to estimate the risks related to droughts, mineral dissolution, saltwater incursion and anthropogenic processes by using GIS and mathematical models.