Groundwater levels and resiliency mapping under land cover and climate change scenarios: a case study of Chitravathi basin in Southern India

Chitravathi basin in India is facing significant challenges as its groundwater resources are facing the impact of land cover and climate change. This study explores the impact of land cover and climate change on groundwater levels and groundwater recharge in the basin using CMIP6 GCMs climate projections data. Taylor Skill Score (TSS) and Rating Metric (RM) were used to rank the GCMs. The top four ranked GCMs, i.e., MPI-ESM1-2-LR, EC-Earth3, MPI-ESM1-2-HR, and INM-CM5-0 were found to produce the most accurate projections under scenarios SSP2-4.5 and SSP5-8.5. Cellular Automata-Artificial Neural Network (CA-ANN) was used to develop future LULC maps. SWAT model was applied for estimating the future groundwater recharge and was calibrated and validated for discharge data, giving the values of R2 = 0.84 and 0.82 and NSE = 0.81 and 0.80 during calibration and validation, respectively. A steady-state groundwater flow model, MODFLOW, was employed to estimate future groundwater levels. Based on the projected groundwater recharge and levels, a resiliency map of the basin was developed. The results indicated that by 2060, under SSP2-4.5 scenario, groundwater levels in the basin would decrease by 54 m, while under the SSP5-8.5 scenario, the decrease would be 62 m. The groundwater resiliency for both SSPs would be poor in 2060. This research will help design and implement adaptation measures to mitigate the impacts of land cover and climate change on Chitravathi basin’s groundwater resources. These findings will help to protect and preserve the basin’s groundwater supplies.