Groundwater resource evaluation in the western part of Kushtia district of Bangladesh using vertical electrical sounding technique

Abstract

Geoelectrical sounding, borehole litholog, and groundwater data have been used for the exploration of groundwater resources in the western part of greater Kushtia district, Bangladesh. This study aimed to delineate the boundary and the depth of aquifers, and assess their vulnerability to near-surface contaminants. Fourteen geoelectrical sounding data are interpreted and the corresponding geoelectrical logs are correlated with the available nearby horehole lithologs. Four distinct geoelectrical layers are identified within the depth of 105 m, namely thin topsoil (8.0-97.6 Om, 0.5-3.6 m), conductive clay-silt-sand layer (8.6-27.5 Om, 1.3-49.4 m), medium resistive fine grained aquifer (25.8-45.0 Om, 10.1-30.4 m), and high-resistive coarse grained water-bearing aquifer (35.0-64.9 Om, 30.0-76.9 m). The shallow aquifer (third layer) is found to occur at a depth ranging between 1.7 and 51 m, whereas the deeper aquifer (fourth layer) is found to occur within the depth between 14 and 52 m, both saturated with water. The groundwater resistivity and formation resistivity factor in the study area is found to vary from 15 to 30 Om and 1.93 to 2.68, respectively. The narrow low-protective layer has made the shallow aquifer highly vulnerable to surface contaminant in the study area