Accurate estimation of climate change impacts on catchment hydrology is essential for effective future water management. The efficacy of such estimations is dependent on proper climate model selection. In this study, an attempt was made to formulate a methodology for climate model selection, evaluating eight climate models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The models were assessed for their ability to simulate variables used in hydrological studies and large-scale atmospheric circulation influencing rainfall in Australia. Five statistical indicators Root Mean Square Error (RMSE), Spatial Correlation (SC), Percentage Bias (Pbias), Normalized Root Mean Square Error (NRMSE), and Nash-Sutcliffe Efficiency (NSE) were used to evaluate the performance, and the models were ranked through Compromise Programming (CP), a multiple criteria decision making technique. Results show that HadGEM3-GC31-LL performed well in most of the categories considered and was top top-ranked model overall followed by GFDL-ESM4, CESM2-CAM6-RT, and CanESM5 for Australia. Conversely, MIROC6 consistently ranked lower in most of the categories. In the context of simulating hydrological variables, CESM2-CAM6-RT, HadGEM3-GC31-LL, and GFDL-ESM4 emerged as the top three models. The robustness of the proposed methodology suggests its applicability for model selection, making it a replicable approach for climate change impact assessment studies in diverse regions.

Groundwater resources have deteriorated in many regions as a result of excessive use to satisfy increasing water demands. Furthermore, climate change has an influence on groundwater in terms of quality and quantity. An investigation of climate change impacts on quality and quantity of groundwater is vital for effective planning and sustainable management of groundwater resources. Despite of the importance of climate change impact studies on groundwater resources, climate change impact studies related to surface water resources have attracted more attention from the research community, leading to limited understanding of the groundwater and climate change relationship. In this paper, a systematic review of the latest literature related to the impact of climate change on groundwater recharge was carried out to provide guidance for future studies.

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.