Multi-criteria assessment and decision-making approach for planning of groundwater recharge structures in a highland watershed

The Gaj watershed in Kangra Valley, situated in the northwestern Himalayan foothills, hosts rock types like limestone, sandstone, and mudstones, which are substantial to support aquifer lithology. The increasing agricultural, industrial, and domestic activities due to soaring population and tourism in this region indicate a future water-stressed scenario, therefore making this study on groundwater management for future resource planning significant. The chosen groundwater influencing factors (geology, land use/land cover change, geomorphology, terrain roughness index, and other major hydrogeological parameters) were checked for multicollinearity using the variance inflation factor, and their thematic layers were analysed using a multi-criteria assessment model. A decadal analysis for groundwater mapping, spanning the temporal range of 2010 to 2022, revealed marked spatial changes, accompanied by noticeable declines in groundwater potential zones associated with lower rainfall intensity patterns in the study area. The results of the study show that in 2010, 4.20% and 37.90% of the area had very high and high groundwater potential, respectively, in the pre-monsoon period. Similarly, 4.46% and 33.77% of the area had very and high groundwater potential, respectively, in the post-monsoon period of 2010. In the year 2022, 2.63% and 37.08% of the study area had very high and high pre-monsoon groundwater potential, whereas 3.20% and 37.76% of the study area had very high and high post-monsoon groundwater potential. The results were validated using the area under the curve (AUC) operator, showing model accuracy of more than 0.80. High-priority zones for artificial recharge structures were identified in the densely populated foothills, where favourable infiltration and a high risk of future drawdown converge.