Groundwater quality assessment using Aq.QA and GIS technique in Azna city, Lorestan province, Iran

Groundwater is the main source of water supply in Azna city located in Lorestan province. The aim of this study is to assess the suitability of groundwater quality for drinking and agricultural purposes, and also revealing the relationship between quality and geological formations in the study region. For this purpose, distribution of pH, electrical conductivity, total dissolved solids, total hardness have been studied by constituent materials of the groundwater samples including chloride, sulphate, sodium, potassium, calcium, bicarbonate. The samples were collected and analyzed from 50 locations of the study area. In the first step hydro-chemistry of water samples has been evaluated according to data of Piper, Wilcox, and Schoeller diagrams in Aq.QA software. In the second step zoning maps of the main parameters were produced in GIS and were compared with the standards of WHO and ISIRI-1053. Finally, these layers were combined and the quality map of groundwater was produced. The relationship of quality map and geological formations was also considered. The results showed, groundwater quality type of the studied stations is Ca-HCO 3 - and Mg-HCO 3 - according to the Piper diagram. About 96% of groundwater samples fall into C1S2 region on Wilcox diagram while only about 4% fall into C1S1 region for irrigation usage. The study region of these groundwater samples is in the proper range for drinking according to the Schoeller diagram. Based on the zoning map, one could realize that the best quality of drinking water is in the calcareous areas that are located at west and south of the city.