Climate change impact on blue and green water resources distributions in Beijiang River basin based on CORDEX projections

This study assessed the potential impact of climate change on spatiotemporal distribution of blue and green water resources in the Beijiang River basin, southern China, using the SWAT hydrological model and CORDEX-EAS regional climate models (RCMs). The outputs of three RCMs (namely RMOH, RMPI and RNCC) under two emission scenarios (RCP 2.6 and RCP 8.5) were bias-corrected by using the quantile delta mapping method for the control (1975-2004), near future (2021-2050) and far future (2061-2090) periods. Driven by the corrected climate variables, future blue and green water were assessed by using the SWAT model calibrated with streamflow data. The results indicated that the green water flow in the northwest basin predicted by RMOH under RCP 2.6 would increase up to about 2.7% in 2061-2090; RNCC suggests that most of the basin would experience the most significant reduction in green water storage (over 30%) under RCP 8.5 in.the far future. For blue water, the ensemble mean of three RCMs indicates a slight decreasing trend in the basin north and an increasing one in the south under RCP 8.5 in.the far future. Our findings could help watershed managers evaluate future hydrological risks and design appropriate adaptation strategies.