Mapping of Groundwater Recharge Potential Zones and Identification of Suitable Site-Specific Recharge Mechanisms in a Tropical River Basin

The increasing demands for the groundwater resources along with decreasing availability, especially in the hard-rock aquifers, call for sustainable groundwater management in India. The present study attempts to identify the potential zones for groundwater recharge, through water conservation measures, in a tropical river basin of Kerala (India), viz., Ithikkara River Basin. The approach enables us to locate the areas suitable for different groundwater recharge structures using remote sensing, geospatial data, and multi-influencing factor technique in the GIS environment. The geo-environmental variables used in the study are lithology, geomorphology, available space for recharge, slope angle, lineament density, soil texture, rainfall, percentage of sand fraction in soil, land use/land cover, and drainage density. The results indicate that lithology, available space for recharge and geomorphology, is the significant variables controlling the groundwater recharge of the study area. The estimated recharge potential zones of the basin are classified into four different classes based on their suitability for groundwater recharge, viz., very good, good, moderate, and least recharge potential zones. Roughly, 50% of the basin area belongs to very good and good recharge zones and is suitable for implementing various groundwater-recharging mechanisms. Based on the variability in the geo-environmental factors of the study area, different artificial groundwater recharge structures (i.e., rainwater infiltration pits, percolation ponds/trenches, injection wells/pond-cum-injection wells and check dams) are suggested using a rule-based approach. The results of the study will be beneficial to the formulation of sustainable groundwater management plans for the region.