Multicriteria Analysis of Groundwater Potential in Valliyur Region, Tamil Nadu: Integrating Remote Sensing, GIS, and Analytical Hierarchy Process

Groundwater is a vital resource particularly in hard rock terrains where surface water availability is limited. Effective mapping and delineation of groundwater potential zones is crucial for sustainable management and utilization of this precious resource. This study aims to delineate groundwater potential zones in the hard rock terrain of the Valliyur region, South India, using an integrated approach combining remote sensing, Geographic Information System (GIS), and the Analytical Hierarchy Process (AHP). Ten thematic layers represent factors influencing groundwater occurrence, including rainfall, topographic wetness index, geomorphology, lineament density, lithology, vegetation index, slope, soil type, land use/land cover, and drainage density derived from various data sources. The AHP multicriteria decision-making method is employed to assign weights to these parameters based on their relative importance, enabling the integration of weighted thematic layers into a groundwater potential index model. The study area is classified into five groundwater potential zones: very low (0.61%), low (2.46%), medium (52.46%), high (41.05%), and very high (3.42%). The predominance of the medium and high groundwater potential zones is attributed to favorable geomorphological features, suitable lithology, moderate to dense vegetation cover, and moderate rainfall conditions facilitating groundwater recharge processes. Validation of the delineated zones is conducted by comparing observed groundwater level fluctuations from 60 bore well samples, demonstrating an overall accuracy of 85% and a kappa coefficient of 0.77. The findings of this study can guide groundwater exploration, artificial recharge initiatives, and sustainable utilization strategies in the water-stressed hard rock terrain of the Valliyur region, while the integrated approach can be applied to other regions with similar geological and environmental conditions.