Evaluation of drinking water quality of Dargaz plain using analytical hierarchy process in geographical information system

The main goal of this research is zoning of Dargaz plain groundwater quality for drinking purposes. Due to increasing population and demanding for new water resources, study and evaluation of water quality is very important. Based on Schoeller diagram and using Analytical Hierarchy Process and pair wise comparison matrix, the optimum weights of every hydrochemical variables are selected. To evaluate Dargaz plain groundwater quality for drinking water, data from 25 wells during 2008 to 2009 were collected. Raster maps of the study area were prepared with different methods of interpolation. Due to uniformly water quality changes in study area we used the Inverse Distance Weighted interpolation method for preparing zoning maps of sulfate, sodium, chlorine, total hardness, electrical conductivity and total dissolved solids. Final weights of hydrochemical variables determined by pair wise comparison matrix and Analytical Hierarchy Process. Finally, with integrating and overlaying the hydrochemical layers and applying the final weights in the GIS environment, the qualitative potential map of study area were prepared. Finally, suitable sites for drinking purpose specified. The results showed that the southwest part of study area has the best groundwater quality for drinking purposes.