Delineation of groundwater recharge potential zones using GIS-AHP and AR feasibility assessment in Prakasam district, Andhra Pradesh, India

Abstract

In water-stressed areas, delineating feasible zones for artificial recharge (AR) to groundwater and pinpointing suitable sites are a challenging task. This study applies a GIS-based analytical hierarchy process (AHP) to delineate groundwater recharge potential zones (GRPZs) by integrating multiple thematic layers. Pairwise comparisons and eigenvalue calculations yielded a consistency ratio (CR) of 0.09, confirming the reliability of the assigned weights. The resulting GRPZs map classifies the 14,122 sq.km study area into five categories: very high (9%), high (17%), moderate (29%), low (31%), and very low (14%). Northwestern and central areas show high recharge feasibility, while the eastern part has low to very low potential. The study also focuses on optimizing and distributing AR structures through a scientific approach for effective planning. Estimations are based on parameters such as weathered zone thickness, total area, rainfall, aquifer volume, water level, runoff, conductivity, and field data like well inventories, lithologs, and yield data. The total estimated unsaturated aquifer volume is 114,135 million cubic meters (MCM), which 124 MCM of surplus rainfall runoff available for recharge. Based on the analysis, a total 3602 artificial recharge (AR) structures, i.e., 2471 check dams (CDs) and 1131 percolation tanks (PTs) have been identified as feasible after accounting 7744 existing structures. Of these, 279 new AR structures (CDs and PTs with recharge shafts (RS)) are proposed in very high to moderate GRPZs. These are expected to harvest 7.17 MCM of rainwater, with 4.30 MCM recharged in drought-prone areas and also promoting farm-dug ponds aid sustainable, cost-effective groundwater recharge. Coastal and shallow water table regions are unsuitable for such interventions.