Mapping of groundwater potential zones by integrating remote sensing, geophysics, GIS, and AHP in a hard rock terrain

Abstract

Groundwater is a life-sustaining resource that provides for society's daily water needs, supports industrial development, promotes agricultural activities, and maintains ecological balance. In groundwater resource studies, integrating remote sensing, geophysical data, and GIS tools play a critical role in monitoring, analyzing, and protecting groundwater resources for water resources development and management. This study used a comparative approach since it is less labour-intensive, inexpensive, and efficient. The potential groundwater zones were determined by integrating various data sources such as remote sensing, geophysical, and collateral data and using the Analytic Hierarchy Process (AHP) method. Fifteen different thematic layers, including geology, geomorphology, lineament density, topsoil resistivity, topsoil thickness, weathered zone resistivity, weathered zone thickness, first fractured resistivity, first fractured thickness, second fractured resistivity, second fractured thickness, slope, land use/land cover, drainage density, and rainfall, were mapped in this process. The results show that the northern part of the study area has a relatively higher response of groundwater potential zones than the southern portion. Agricultural areas near surface water bodies and forests, characterized by shallow to moderately weathered pediments and pediplains, exhibit favourable groundwater potential. The study identifies five distinct groundwater potential categories based on area coverage:very low (242.44 km2), low (147.52 km2), medium (241.72 km2), high (26.35 km2), and very high (18.51 km2). The predominant factors influencing the groundwater potentiality are top soil thickness, pediment as well as pediplain (shallow to moderately weathered), lithology (charnockite and fissile hornblende biotite gneiss), slope type (gentle), and rainfall (high). A very good correlation between the groundwater potential zones and the well yield aided in validation of the above findings.