Runoff Simulation on the Impact of Climate Change in the Shiyang River Basin
气候变化下石羊河流域径流模拟与影响量化

The Shiyang River Basin has a highest utilization rate for water resources. In this study, a distributed hydrologic model (SWAT) of the middle and upper region of Shiyang River Basin was developed and validated to quantify the impact of climate change. Runoff variation characteristics in the four periods were simulated: 1990s(1988 to 2005), 2020s(2020-2037), 2050s(2050-2067) and 2080s(2080-2097) under different future scenarios and the impact of climate change on future hydrologic regimes and water resources quantified. We found that runoff in every tributary was better simulated based on SWAT and the accuracy supported the impact analysis of future climate change. For the unregulated stations (Zamusi and Jiutiaoling), the average efficiency coefficient was greater than 0.75 and the average relative coefficient was greater than 0.80. For regulated stations expect Shibalipu reservoir, the average efficiency coefficient was greater than 0.40 and average relative coefficient was greater than 0.60. Comparing A2 and B2 scenarios with baseline (1990s), future precipitation and potential evapotranspiration in the 2020s, 2050s and 2080s increase continuously. The rate of monthly precipitation is from -12% to 134% in A2 scenario, -2% to 98% in B2 scenario while the rate of monthly potential evapotranspiration is from 3% to 29% in A2 scenario, 1% to 19% in B2 scenario. The rate of precipitation is greater and the most significant month is April for precipitation and August for potential evapotranspiration. Thus, runoff also increases continuously, but the rate is lower. Comparing the precipitation and potential evapotranspiration under A2 with B2 scenarios, the rate of increase for both in A2 are higher than for B2. Runoff in the middle and upperstream of the Shiyang River Basin will increase slightly; at Zamusi station, it increases from 7.31m3/s in 1990s to 7.97m3/s (A2 scenario) and 7.45m3/s (B2 scenario) in 2080s. The increasing rate is between 1.37% and 9.03%. At Xiying station, it increases from 8.14m3/s in the 1990s to 8.55m3/s (A2 scenario) and 8.26m3/s (B2 scenario) in 2080s. The increasing rate is between 0.12% and 5.04%. The increasing rate in A2 is a greater than for B2 scenario. All studies are expected to support an integrated river basin water resource management system for the Shiyang River Basin under a changing climate.