ABSTRACT
ABSTRACT: Electrical resistivity imaging survey has been conducted to define the geometry of aquifer configuration in Pathri-Rao watershed situated in the Piedmont zone of Himalayan foot hill region, Uttaranchal (presently Uttarakhand), India. Resistivity image profiling data at 9 sites were recorded using IRIS imaging system with 72 electrodes deployed at 10 meter spacing in each site. The profile length at each site was 710 m, oriented in different directions in field as per the survey design and accessibility of space. 2D inversion of each profile data was carried out with topography data using RES2DINV code. Interpreted 2D resistivity image were analyzed in terms of geological formation and geometry of aquifer system in the area. Interpreted resistivity data reveals the unsaturated surface layer resistivity range 100-800 -m. Clay formation is characterized by low resistivity (10-25 -m). Resistivity of aquifer zone in the study area varies from 40-150 -m. Depth, thickness, surface elevation, possible groundwater flow direction and the interaction of shallow and deeper aquifers were also inferred from resistivity image. The results are in general agreement with the results obtained from isotope technique and other hydro-geological data obtained from the area.
