ENVIRONMENTAL THREATS TO GROUNDWATER AND ITS EVALUATION OF HYDROCHEMICAL SUITABILITY FOR DRINKING AND IRRIGATION PURPOSE IN THE GOKPINAR DAM BASIN, DENIZLI - TURKEY

Abstract

This study aims to evaluate the hydrochemical properties of groundwater in the Gokpinar Dam basin and its suitability for drinking and irrigation purposes. The dam was built primarily to provide irrigation water for agricultural land downstream. On the other hand, groundwater upstream of the dam is both a vital resource for all the needs of the rural people, as well as providing water for the reservoir and all surrounding springs. The basin is under the pressure of anthropogenic potential pollutants such as agriculture, highway, industry, sewage, domestic wastewater, trout and horse farms. The groundwater samples collected from water wells the basin were analyzed in accordance with standard test procedures for the main quality parameters. The dominant hydrochemical facies of groundwater is the Ca2+ - Mg2+ - HCO3- type. In all samples, alkaline earth metals (Ca2+, Mg2+) and weak acid (CO32-, HCO3-) dominates over the alkalies (Na+, K+) and strong acid (Cl-, SO42-). All of the groundwater samples fall in the rock dominance field. The major reactions contributing to the groundwater chemistry are dissolutions of calcite and dolomite. The trace elements, nitrate and nitrite concentration of all samples fulfill the drinking water standards. Despite potential threats in the basin, the results of the hydrogeochemical assessments have shown that groundwater can be safely used for drinking and irrigation for now. However, it is clear that the pressure on groundwater resources in the basin will increase rapidly due to the increasing water demand and climate change.