Abstarct: Geoelectrical method was applied in Miami area, located in semnan Province, to determine the lateral and depth extents of water-bearing formation. In this thesis, 1-D and 2-D interpretation of resistivity sounding data has been carried out. 1-D interpretation has been carried out using master curves and softwares such as VES and Ipi2win. I-D interpretation results shows that the resistivity values are higher in the north of the study area. baxsed on these results, the resistivity of the water bearing laxyer in the study area has been estimated 30-40 Ω.m. (according to hydrologic parameters obtained from three water wells in the study area, such as TDS and EC that are less than 1000 units). 2-D interpretation of resistivity sounding data also has been carried out using different software packages such as Ipi2win and Res2dinv. We should mention that these two softwares are used to obtain geoelectric cross sections that show resistivity 2-D variations in the study area. The 2-D interpretation results also verify the higher resistivity values in the north of the study area. Obtaining a linear relationship between the results of 1-D interpretation of resistivity sounding data and hydrologic parameters obtained from three water wells in the study area, we use water resistivity values of the water-bearing laxyers (R_w) nearby the water wells and hydrologic parameters obtained from these wells (such as TDS and EC). ObtainingR_w, we should first compute the formatin factor (F) of the water-bearing laxyers nearby the water wells using porosity values (φ) of these laxyers. For this, we use the Archie’s law which is a simple relationship between porosity and formation factor.¬ We should mention that 1-D interpretation of resistivity sounding data gives us the resistivity of water-bearing laxyers (R_(o )). When we computed F values using Archie’s law, the water resistivity values of the water-bearing laxyers (R_w) is obtained using a formula which is a simple relationship between F, R_(o )and〖 R〗_w. Finally, a linear relationship has been obtained between 1-D interpretation results (in the other wordsR_w) and hydrologic parameters obtained from these three water wells (such as TDS and EC) using regression method.