Ali Rajabi - School of Geology, Department of Engineering Geology, University of Tehran, Tehran, Iran
Keyvan Mokhtari - Regional Water Authority, Markazi Province, Water resources offices of Delijan, Iran

This study was conducted to evaluate the quality of the groundwaters and the impact of geological units on these waters in Hastijan area. For this purpose, 11 samples of water resources have been collected with their appropriate dispersal. Physico-chemical parameters of Mn, Ni, Cd, Cu, Zn, As Fe, Cr, and ions K+, Na+,Ca2+, Mg2+, Cl-, So42-, Hco3- as well as indicators TH, TDS, EC, PH were determined. In order to assess the water quality, the Piper diagram, Gibbs diagram, sodium absorption ratio (SAR), chloro alkaline index (CAI), the saturation index (SI), heavy metal pollution index (HPI) and the metal index (MI) were used. Investigating surrounding rocks of the area showed the existence of limestone, dolomite, sandstone, marl, shale with layers of gypsum have declined the quality of water and have specially increased the salinity and concentration of Na+ and Cl- in groundwater resources of the study area. The calculation of saturation index indicated that these waters are super-saturated toward the dolomite and calcite minerals and under-saturated toward sulfate minerals. The iron concentration in about half of the samples was higher than the standard limits of 0.2ppm caused by iron-bearing sandstones of Zaigun and Lalun formations located just upstream of springs.

groundwater quality, Geological units, drinking water, Hastijan area, Delijan