Hydroclimatological response to dynamically downscaled climate change simulations for Korean basins

We investigated the hydrological response to climate change simulations for three basins in South Korea. To provide fine-scale climate information to the PRMS hydrological model, an ECHO-G B2 simulation was dynamically downscaled using the RegCM3 double-nested system implementing two different convection schemes, namely, the Grell and the MIT-Emanuel (EMU) schemes. The daily minimum and maximum temperatures and precipitation from the nested domain for a grid spacing of 20 km are used as the input for the PRMS run. Two sets of multi-decadal simulations are performed over a reference period (1971-2000) and a future period (2021-2050). We focus on the differences of hydrological impacts in response to both simulations with different performances. Based on the validation of the reference simulations, the EMU simulation shows considerable improvement compared to the Grell simulation, indicating a reduction in the cold and dry biases during summer. This improvement is directly reflected in the hydrological simulation of evapotranspiration and runoff. However, using the RCM simulations without bias-correction showed the limitations of hydrologic simulation, especially snowmelt. Despite large differences in both reference simulations, the change signals of temperature and precipitation derived from the differences between the reference and future simulations show a similar pattern and sign. However, the differences in monthly change in precipitation and temperature between Grell and EMU caused the relatively large differences in runoff changes in the study areas.