ASSESSMENT OF GROUNDWATER QUALITY OF EAST THRACE, TURKEY FOR IRRIGATION PURPOSES WITH THE AID OF GEOGRAPHICAL INFORMATION SYSTEMS

Abstract

Quality of irrigation waters has always been a major concern for crop yield. The study area (Thrace) is one of the main wheat and sunflower production lands of Turkey. In this study quality of groundwaters used for irrigation purposes in east Thrace was assessed. For this objective, groundwater samples (n=18) were collected from deep irrigation wells and later were analyzed for chemical properties.The samples were analyzed for pH, total dissolved solids (TDS), and concentrations of HCO3-, NO3-, Na+, K+, Ca2+, Mg2+ and Cl and spatial distribution maps of these ions and cations were prepared by Geographic Information System (GIS). Subsequently sodium ratio (Na%), sodium absorption ratio (SAR), residual sodium carbonate (RSC) and magnesium hazard (MH) indices of these waters were calculated and spatial distribution maps were prepared by GIS. Distribution maps of these indices showed that majority of the groundwaters in the study area were suitable for irrigation.