Delineation of groundwater potential zones using GIS and AHP techniques in Coimbatore district, South India

The study aims to demarcate groundwater potential zones in the Coimbatore district of South India using geographic information system (GIS), remote sensing (RS), and multi-criteria decision analysis (MCDA) methods. A total of 10 thematic layers such as geomorphology, geology, lineament density, land use/land cover (LULC), soil, drainage density, rainfall, slope, curvature and topographic wetness index (TWI) were created and analysed for groundwater potential zone delineation. The analytical hierarchal process (AHP) was employed to assign suitable weights to various thematic maps. The Weighted sum overlay analysis tool of ArcGIS 10.5 was used to overlay the thematic layers to generate the study area's groundwater potential zone (GWPZ) map. The resulting map was categorised into excellent, good, moderate, and poor. The findings indicate that about 16% and 37% of the study area is classified as poor and moderate groundwater potential zones, respectively, while approximately 26% and 21% fall under the good and excellent potential zones. The obtained results were validated using pre-and post-monsoon groundwater fluctuation data, which demonstrated consistency with the methodology adopted. Overall results prove the efficacy of using geospatial technology in combination with AHP in delineating groundwater potential zones. Hence, the results obtained can be helpful for decision-makers in the planning and management of groundwater resources and for locating the sites for new borewells in the study area.