Delineation of Groundwater Potential Zones in River Basins Using Geospatial Tools—an Example from Southern Western Ghats, Kerala, India

Abstract

The remote sensing and geospatial tools have wide applications in water resource assessment studies. Satellite images are increasingly being used in groundwater exploration because of their utility in identifying various geomorphic features. The present study has been carried out in two important river basins—the Ithikkara and the Kallada river basins, of Southern Western Ghats, Kerala, India. The groundwater potential zones are delineated from 14 thematic layers such as drainage density, geomorphology, slope, lithology, soil, land use/land cover, lineament density, topographic wetness index, rainfall distribution, roughness, curvature, dissection index, depth to water level and topographic position index using multi-criteria evaluation method. Integration of the factors has been performed in GIS platform using weighted overlay analysis. Different classes of thematic maps have been assigned weights based on influence on groundwater hydrology (through discussions with the experts in the field), and finally, factor ranks are assigned. The final map indicates the potentiality values of groundwater occurrence in the study area, which was classified into three categories—high, moderate and low. A total of 37.2% of the study area fall in low groundwater potential zone, 42.3% in moderate potential zone and 20.5% of the area in high potential zone. The groundwater potential zones delineated using the method are validated with data of springs and dug wells from field investigations, and it was found that the overlay method using GIS and remote sensing gives 95% accuracy.