Evaluation of groundwater resources in Varzeqan City by introducing unsupervised combination method to determine the categories of drinkability

Varzeqan plain is exposed to extensive agricultural and mining activities, as well as the presence of nitrate and arsenic anomalies in the water resources and supplying drinking water from groundwater resources need to asess the groundwater quality. The results of the analysis of groundwater resources in Varzeqan plain in 39 sampling points for 13 effective parameters including major, minor and trace elements, physical and chemical properties, were used to determine drinking water quality. Results of health risk for groundwater consumers and according to the standards of the World Health Organization (WHO) and the Iranian Industrial Research Standard (ISIRI), show that the most effective of these parameters in the quality of drinking water is nitrate and arsenic. In this study, GQI and GWQI indicators were used for evaluation, and according to the output maps of these two indicators, which show the difference in determining the quality of drinking water in the region, It was not possible to select one of these two indicators to determine the drinking ability of water resources in the region, In order to achieve a single map that more accurately expresses the quality categories of drinking water in the area, the unsupervised method was introduced and used, and the results show that the unsupervised method with a higher CI than the results of the two indicators is a more ideal method for assessing the quality of water resources in the region and it is more accurate to determine the drinkability categories of these resources.