基于CMIP 6多模式的长江流域气温、降水与径流预估

Temperature,precipitation and runoff prediction in the Yangtze River basin based on CMIP 6 multi-model

【目的】探究未来气候变化对长江流域径流的影响,为长江流域及其他地区的早期洪水预警和防御措施提供依据。【方法】采用国际耦合模式比较计划第6阶段(CMIP 6)多模式集合平均(MME),结合SWAT水文模型,对长江流域1961—2014年气温、降水量和径流等进行评估,并预估了长江流域2020—2099年SSP1-1.9、SSP1-2.6、SSP2-4.5、SSP3-7.0、SSP5-8.5排放情景下的气温、降水量和径流。【结果】(1)相比单一模式,MME历史时期模拟气温和降水效果更好,与观测值的相关系数均大于0.90,MME可以很好地模拟出气温和降水量的空间分布规律。(2)由MME分析可知,2020—2099年长江流域在所有情景下的气温增幅低于50%,降水增量小于20%,在SSP5-8.5情景下模拟的温度值比SSP1-1.9时的温度值高1.23℃,比SSP1-2.6时的温度值高0.99℃。(3)总体上,长江流域未来的年均径流量增加显著,到21世纪末,SSP5-5.8情景下年均径流量将达到40380 m^(3)/s。【结论】本研究揭示了长江流域径流变化趋势与气温与降水之间的相互关系,以及模拟未来气候变化的准确度,同时认为未来长江流域气温、降水量与径流量均呈上升趋势,低碳排放情景下的洪涝灾害相对较少,可为以后长江流域洪涝灾害的预估和区域性气候变化提供依据。

[Objective]This research aims to explore the impact of future climate change on predicted runoff trends in the Yangtze River basin and provide a basis for early flood warning and prevention measures in the Yangtze River basin and other regions.[Method]Temperature,precipitation and runoff in the Yangtze River basin from 1961 to 2014 were evaluated by using the multi-mode set average(MME)of the international coupled model intercomparison project phase 6(CMIP 6)and the SWAT hydrological model and predicted under SSP1-1.9,SSP1-2.6,SSP2-4.5,SSP3-7.0 and SSP5-8.5 emission scenarios from 2020 to 2099.[Result](1)Compared with the single model,MME showed better performance in simulating temperature and precipitation during historical periods,with a correlation coefficient with the observation value was>0.90.Further,MME simulated the spatial distribution of temperature and precipitation well.(2)The MME analysis showed that during 2020 and 2099,temperature and precipitation increases in the Yangtze River basin under all scenarios were<50%and<20%,respectively.Simulated temperature under the SSP5-8.5 scenario was 1.23 C higher than that under the SSP1-1.9 scenario,and 0.99℃higher than that under the SSP1-2.6 scenario.(3)Overall,future annual runff of the entire Yangtze River basin increased significantly and reached 40380 m^(3)/s under the SSP5-5.8 scenario at the end of the 21st century.[Conclusion]Temperature,precipitation and runoff in the Yangtze River basin are predicted to increase in the future,whereas flood disasters under low emission scenarios are relatively less likely.