Evaluation and zoning of the quality of drinking water wells in Torbat Jam and Saleh Abad cities based on the WQI index and GIS software

The purpose of this study is to determine the quality of underground drinking water sources in Torbat Jam and Saleh Abad cities using quality index (WQI) and their zoning.In order to determine the quality index of water resources, the results of testing 9 parameters including: (PH, hardness, dissolved solids, calcium, magnesium, sodium, nitrate, chlorine and sulfate) were studied.Samples were taken from 110 spring wells and aqueducts in the region and transferred to the central laboratory of Khorasan Water and Wastewater Company headquarters, which has a standard certificate of 17025 for water chemical tests and the experiments were measured according to the latest standard version of the method in 2005 by the IC chromatograph device.In the final stage, after determining the quality status of drinking water wells, their quality zoning was done in ARC GIS10.2 software.Zoning maps of water resources quality showed that most of the water resources of Torbat Jam city are in the range of excellent and good water quality in terms of WQI index.Also, the results of statistical techniques (multiple regression) showed that sodium (Na) parameter had the highest influence coefficient in determining the WQI index, followed by sulfate, total hardness, chlorine and dissolved solids.Investigating the significance level of land use with quality index by Kruskal-Wallis test showed a significant difference between land use and water quality index.