Abstarct: The goal of this research is groundwater resources exploration in hard formations, by inverse 2D modeling with resistivity data. These data are acquired by symmetric pole- dipole array in Kal Ghornoo valley in west Shahrood. This survey carried out near a water well named “Zobahan”. To facilitate comparison between results of the measured data with the subsurface geology of the well environment. Practical researches for identification of geometrical situation of joints and cracks of the place to be studied. Practical researches such as cracks dip and strike determination and rock type thin section studies show that joints and cracks of this valley have a dip more than 80 degrees and a north south strike. Theoretical studies have shown that pole- dipole array is a suitable array for lateral inhomogeneity resistivity. In this research to prove this claim, sensitivity sections of arrays and mathematical models have been used. According to what discussed, geoelectrical measurements carried out by symmetric pole- dipole array and the acquired data have been modeled by Res2Dinv software. The resulting 2D models, properly show the saturated joints and cracks.The interesting results which concluded from this research, is that lateral inhomogenties properly could be explored from geoelectrical measurements by symmetric pole- dipole array and modeling of the obtained data by Re2Dinv software.