Assessing the impact of climate change on groundwater recharge in the Lower Campaspe River Basin

ABSTRACT Groundwater recharge underpins water security in the highly allocated, semi-arid Campaspe River Basin, but its climate-sensitive future response remains poorly quantified, creating uncertainty for groundwater planning. This study assesses the impact of climate change on groundwater recharge in the Lower Campaspe River Basin using SWAT model calibrated with observed streamflow data for recharge projections. Future projections from two CMIP6 climate models (GFDL and CESM) under low (SSP126) and high (SSP585) emission scenarios were bias corrected using Quantile Mapping and used as inputs into the calibrated SWAT model. Results reveal strong inter-model variability, pronounced spatial contrasts with a north–south gradient, and significant differences across emission scenarios and future periods. Under SSP126, ensemble-average recharge is projected to increase by 62% in the near future, decline by 17% in the mid future, and rise again by 43% in the far future. In contrast, SSP585 simulations indicate consistent reductions in recharge, with average declines of 38, 26, and 32%, respectively. The findings highlight precipitation as the main driver of recharge, with CESM projecting stable or increased recharge under wetter conditions, while GFDL projects substantial declines under drier, warmer scenarios. These recharge projections provide a robust basis for sustainable groundwater planning in the region.