Abstract

The chemical analysis of groundwater samples in 29 well in the Zahedan, Sistan and Baluchestan Province, southeast of Iran was evaluated to determine the hydro-chemical processes and assessment of groundwater quality. In present study the Geographic Information System (GIS) approach was used for Groundwater Quality Index(GQI). The value of this index was reported to be in the average range 48.21% that due to the high amounts of electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), sulfate ( , chloride (Cl−) and sodium (Na+)in the water resources. The Gibbs diagram indicated that groundwater chemistry in this area has obtained mainly from evaporation dominance. Assessment of hydrochemical characteristics using Piper trilinear diagram indicates Na–Cl as the predominant hydrochemical facies. Estimates show that water quality in the area has declined. The reasons for the decline in groundwater quality include the lack of rainfall, incomplete feeding of the aquifer and geology of the surrounding area. Finally, solutions were proposed to maintain and improve groundwater quality in the region.