Assessment of water resources quality of a karstic aquifer in the Southwest of Iran

Abstract

In this study, the pollution risks related to arsenic, fluorine, iron, physicochemical parameters, and various indices have been investigated in the Bazoft dam site. The proposed dam is a double-curvature arch dam with a height of 211 m in order to produce hydroelectric energy and the supply of agricultural and drinking water in the west of Iran. Chemical analysis of water samples obtained from springs, river, and boreholes in the dam site was conducted. Anions such as HCO3, Cl, SO4, CO3, and NO3, and cations including Ca, Na, Mg, K, F, Fe, and As had the highest amounts, respectively. The concentration of assessed variables was lower than the WHO permissible limit. The results of the principal factor analysis (PCA) showed that four factors control 82% of the water quality variations. The factors such as EC, TDS, Na, K, SO4−, CO3, HCO3, total hardness, and alkalinity with 43.10% were the most important factors in the dam site. The heavy metals of iron and arsenic have no meaningful relationship with any of the ions. The accuracy of the relations was investigated based on different statistical criteria. The main processes in controlling the water quality are weathering and the dissolution of the carbonates caused by the interaction of water and rock. Ionic ratios indicated that the water origin of the springs is the dolomitic aquifers and the main source of magnesium is carbonate dissolution. The water resources of the dam site are corrosive, and all indices indicate the appropriate quality of water for irrigation and drinking purposes. Filed studies and boreholes water level variations showed that karstification is limit in the dam site.