Temporal And Spatial Changes Of Water Supply Capacity In Xiangjiang River Basin Under Future Climate Scenarios

In recent years,due to the impact of climate change and human activities,the problems of ecosystems and water resources around the world have become increasingly serious.Assessing the impact of climate change on water supply in the future is of great significance for formulating rational water resources management and development strategies as well as ecosystem protection.In this study,the Xiangjiang River Basin,a typical subtropical monsoon climate basin in southern China,is taken as the research area.The SDSM（Statistical Downscaling Model）and InVEST（the integrated Valuation of Ecosystem and Tradeoffs model）is applied to simulate the temporal and spatial changes of water supply in the basin under current and future climate change scenarios.In order to provide scientific basis for decision-making of water resources management,the impact of future climate change on water supply in Xiangjiang River Basin was explored.The main contents and research results are as follows:（1）InVEST model shows good applicability in the Xiangjiang River Basin,and the fitting degree of the simulation results and observation series on the annual scale is ideal.The relative error is 4.95%,R² is 0.74 and RMSE is 75.17.Moreover,in the four simulation periods of 2000,2005,2010 and2015,it shows that it can well simulate the temporal and spatial changes of water supply in the Xiangjiang River Basin.（2）SDSM also shows good applicability in the Xiangjiang River Basin,which can well simulate the annual maximum,minimum temperature and precipitation changes in the Xiangjiang River Basin.The simulation R² of precipitation is 0.54 and RMSE is 165.7 mm.The simulation of temperature is better,R² is above 0.96,RMSE is only 0.4℃.（3）Using measured meteorological station data,NCEP（National Centers for Environmental Prediction）reanalysis data,and Representative Concentration Pathways,RCP2.6 and RCP4.5 greenhouse gas emission scenarios under CanESM2 atmospheric circulation model,the climate changes of the Xiangjiang River Basin in the three future periods of 2020s（2020-2035）,2050s（2050-2065）and 2080s（2080-2100）are predicted based on SDSM model.The results show that under RCP2.6 scenario,the minimum temperature and the maximum temperature increase in 2020s and 2050s.While in 2080s,the minimum temperature does not continue to increase and the maximum temperature even decreases.But they still increased by about0.5℃and 0.8℃respectively,compared with the benchmark years（2000-2015）.Under RCP4.5 scenario,the minimum temperature and the maximum temperature in the next three periods all show a rising trend.In2080s,the minimum temperature and maximum temperature increase by about 1.5℃and 1.4℃respectively,compared with the benchmark years;while the precipitation changes little in 2020s under both scenarios.The annual average precipitation in 2050s increases by 9%under RCP2.6 scenario and 18%under RCP4.5 scenario.In 2080s,the annual average precipitation in increased by 10%under RCP2.6 scenario and 20.4%under RCP4.5scenario,compared with the benchmark years.（4）In the prediction of water supply in the future period of Xiangjiang River Basin,the results show that there is little difference between the two scenarios and the water supply in the base period in 2020s.During 2050s,the water supply of Xiangjiang River Basin in RCP4.5 is much higher than that in RCP2.6,which increases by 18.8%under RCP2.6 and 33%under RCP4.5,which is 9.4×10³ m³ha^-1.In 2080s,the water supply of Xiangjiang River Basin has increased by 33.5%compared with the base period,and by 19.3%under RCP 2.6.