Hydrological projection for the Miyun Reservoir basin with the impact of climate change and human activity

Considering the impact of climate change and human activity, hydrological projection in the Miyun Reservoir basin (MYRB) was estimated by the Variable Infiltration Capacity (VIC) model with the output from NCAR-CCSM3 under A1B, A2, and B1 scenarios in 2010-2099. Climate change was the change of temperature and precipitation; and human activity included water withdrawal from river, hydraulic projects, land use/covers change, etc. The VIC model parameters were calibrated in “natural period” without the impact of human activity, i.e., before the breakpoint of the precipitation-runoff double cumulative curve. In order to consider the impact of human activity, the Hydrological Projection Revision Formula was constructed to revise the hydrological projection in two catchments (Xiakuai and Zhangjiafen catchment) covering most parts of the MYRB. Based on the output from NCAR-CCSM3, the MYRB would become warmer and wetter in future climate change scenarios. The results indicated that there might be a slight decreasing trend for runoff in 2020s (2010-2039), but the runoff would increase in 2050s (2040-2069) and 2080s (2070-2099) in MYRB under three climate change scenarios. For example, in 2050s the runoff might increase by 35.2-90.4% and 14.3-51.6% in Xiakuai and Zhangjiafen catchment, respectively, compared to the baseline period (1961-1999). Meantime, a high uncertainty for hydrological projection in MYRB should be focused, because only one GCM was used in this study.