Groundwater potential zonation in the Siwalik of the Kankai River Basin, Eastern Nepal

Abstract

For the globally degrading groundwater resources in terms of quantity and quality, proper assessment and management become crucial for their sustainable use. This study aims to delineate the groundwater potential zones using an integrated approach of geographic information system (GIS) and the Analytical Hierarchy Process (AHP) in the Siwalik of the Kankai River Basin, Eastern Nepal. Different thematic layers like hydrogeomorphology, land use/land cover, lithology, slope, topographic wetness index, drainage density, normalized difference vegetation index, lineament density, and aspect were prepared and processed with suitable weights on Saaty's scale. The delineated groundwater potential zones in the study area were categorized as low, moderate, and high. The results showed that approximately 49.38% (130.85 km2) of the total study area has a low potential for groundwater. The moderate zone includes approximately 35.5% (94.07 km2) and the high potential zone includes only 15.05% (39.88 km2) of the area. The potential map was validated with a 70.6% prediction rate using the spatial distribution of the springs in the area. The analysis shows that hydrogeomorphology, LULC, and lithology have a significant control on the occurrences of groundwater. The study signifies the scarcity of groundwater resources, which needs a better management plan and strategies for sustainable use.