未来气候变化情景下长江上游年径流量变化趋势研究

依据政府间气候变化委员会(IPCC)第五次评估报告(AR5)未来不同排放情景(RCPs)下的多模式(CMIP5)气温和降水预估结果，构建基于气温和降水的未来径流量预估模型，并以宜昌站为例分析了不同模式不同排放情景下未来80年(2020～2099年)长江上游年径流量的变化趋势。多模式集合平均预估结果表明：在99%的置信水平下，未来80年长江上游年径流量在RCP2.6排放情景下呈不显著增加趋势，在RCP4.5排放情景下呈不显著减小趋势，而在RCP8.5排放情景下则呈显著减小趋势；在RCP2.6、RCP4.5和RCP8.5排放情景下未来80年长江上游年径流量预估均值相对于1961～2000年分别减少6.42%、10.99%和13.25%；同时，未来80年长江上游年径流量变化具有一定的年代际特征，在RCP2.6和RCP4.5排放情景下21世纪初期偏多、中期偏少而后期变化并不明显，在RCP8.5排放情景下则是21世纪中期以前偏多而中期以后明显偏少。本研究方法可为未来气候变化情景预估分析提供技术参考，本研究成果可供气候变化背景下长江上游乃至长江流域水资源开发利用及对策分析提供决策依据。

Trends Variability of Annual Runoff in the Upper Reaches of Yangtze River under Future Climate Change Scenarios

According to the air temperature and precipitation from the projection of IPCC fifth assessment report (AR5), an estimation model of annual runoff is presented in this paper. As an example, the variabilities of annual runoff in the upper reaches of Yangtze River are studies under the different future climate change scenarios of 5 GCMs, which have been analyzed and applied in the IPPC AR5. The results show that the annual runoff time series is a non-significant tendency under the RCP2.6and RCP4.5 scenario, while there is a significant deceasing trend for the annual runoff time series under the RCP8.5 scenario during the period of 2020～2099 at the 99% confidence level. On the other hand, under the RCP2.6, RCP4.5 and RCP8.5 scenario, the decrease in average annual runoff from 2020 to 2099 is 6.42%, 10.99% and 13.25% respectively compared with that of 1961～2000. The work aids understanding of the climate of the upper reaches of Yangtze River under global warming and provides information for regional planning and management of water resources.