Mapping of laterite zones using 2D electrical resistivity tomography survey in parts of Paschim Medinipur, West Bengal, India: An approach for artificial groundwater recharge

Abstract

Earth’s most valuable and renewable resource ‘groundwater’ is depleting rapidly in the last few decades. Due to lack of proper usage and planning of groundwater leads to water scarcity in some problematic areas of Paschim Medinipur, West Bengal, India. The presence of impervious laterite on the surface as well as in the subsurface is the main problem that hinders the natural groundwater recharge in the area. To overcome this issue, artificial recharge of groundwater and rainwater harvesting can be the best solutions. However, this requires precise information about the subsurface structures. Therefore, 2-dimensional Electrical Resistivity Tomography (ERT) surveys are performed at nine locations (separated by 3–4 km distances) covering a distance of about 30 km along a profile in E–W direction centrally located between Kangsavati (in the north) and Subarnarekha (in the south) rivers. The present study area extended between Village Chirakuti in the west to Village Nandakishorpur in the east, in the Paschim Medinipur district of West Bengal. A principle profile line of 30 km with a station interval of 3–4 km is covered along east–west direction. 2D data is collected at nine locations (with 800 m spread) along the principle profile. Every dataset is interpreted using RES2DINV software. The study reveals that the observed resistivity is highest in the western part (1400 Ωm) and lowest in the eastern part (40 Ωm) of the principle profile. The 2D interpreted resistivity cross-sections reveal that, the western part of the principle profile has conductive layers overlaid by a resistive layer on the top. The eastern part of the principle profile represents flat younger alluvium deposits. Most of these sediments are clayey sand, coarse sand on top and hard clay, small gravels to 10 mm gravels in deeper parts. The water crisis is mainly in the western part. So puncturing the top laterite layers and allowing the runoff water to penetrate into the subsurface may solve the problem. Building watersheds for agriculture in the western part of the principle profile line could help in increasing of the groundwater level in the study area.