Assessing the impacts of climate and land cover change on groundwater recharge in a semi-arid region of Southern India

This study examined how Land Use Land Cover (LULC) and climate affect groundwater recharge in Southern India’s semi-arid region. Coupled Model Intercomparison Project Phase6-Global Circulation Models (CMIP6-GCMs) climatic data is used to generate climate projections for the future. The GCMs are ranked for precipitation and temperatures using the Taylor Skill Score (TSS). Rating Metric (RM) is preferred to establish the final rank of the GCMs. Ensemble of projections from the top four ranked GCMs: Max Planck Institute Earth System Model version 1.2 - Low Resolution (MPI-ESM1-2-LR), European Consortium Earth System Model version 3 (EC-Earth3), Max Planck Institute Earth System Model version 1.2 - High Resolution (MPI-ESM1-2-HR), and Institute for Numerical Mathematics Coupled Model version 5 (INM-CM5-0) are used as they estimated the most reliable forecasts for all the three considered parameters. MPI-ESM1-2-LR is the top-ranked GCM with an RM of 0.92. The future LULC map is produced using Cellular Automata and Artificial Neural Networks (CA-ANN). Soil and Water Assessment Tool (SWAT) is used to evaluate the individual impact of climate change on groundwater recharge and the combined impacts of LULC and climate change on groundwater recharge in water-stressed regions (semi-arid) using standard modelling techniques. The SWAT model has been calibrated using monthly discharge data from a gauging station, resulting in an overall accuracy of R² = 0.83 and NSE = 0.81. The SWAT groundwater module is employed to estimate recharge across different time frames: baseline (1985–2014), near-future (2015–2030), mid-future (2031–2060) and far-future (2061–2100), considering moderate (SSP2-4.5) and extreme (SSP5-8.5) emission scenarios. Results indicate that under constant LULC conditions, recharge varied between 135 and 215 mm/year for SSP2-4.5 and 149 to 316 mm/year for SSP5-8.5. Notably, compared to the baseline recharge of 116.4 mm, future groundwater recharge increased under both SSP scenarios. The observed variations in recharge carry significant implications for understanding how varied emission scenarios may impact groundwater resources over the specified time periods.