气候变化条件下雅砻江流域未来径流变化趋势研究

Long-term runoff change trend of Yalong River basin under future climate change scenarios

雅砻江为我国重要的水电基地,未来气候变化条件下流域径流变化将直接影响雅砻江梯级水库群运行安全和发电调度,因此研究气候变化对雅砻江流域径流的影响十分必要。首先建立了流域月尺度的SWAT模型,然后使用统计降尺度模型(SDSM)模拟未来2006—2100年流域内各站点的气象数据,最后使用流域SWAT模型对未来2006—2100年月径流进行模拟。结果表明,未来雅砻江流域径流呈上升趋势,且增幅随着辐射强迫的增加同步增大,RCP2.6、RCP4.5、RCP8.5这3种典型浓度路径下年平均径流增幅分别为8.9%、12.5%、16.7%,且2020S(2006—2035年)、2050S(2036—2065年)、2080S(2066—2100年)这3个时期年径流量呈现不同的变化趋势,其中RCP2.6浓度路径下为先逐步增加达到峰值后略有减少,RCP4.5浓度路径下为先逐步增加达到峰值后趋于稳定,RCP8.5浓度路径下为持续增加。流域径流年内分配方面,3种典型浓度路径下汛期径流占全年比例在2020S、2050S、2080S这3个时期均为先降后升趋势,整个预测期总体为降低趋势,RCP2.6、RCP4.5及RCP8.5这3种浓度路径下整个预测期的均值分别由基准期的75.9%降低为72.9%、72.0%、71.2%。径流增加会对流域洪水特性产生较大影响,为此应该修正流域设计洪水计算结果和调整防洪调度方案,以降低雅砻江流域梯级水库群因气候变化而产生的运行风险,并提高发电调度效率。

Yalong River basin is an important hydropower base in China.The runoff variation of Yalong River basin under climate change scenarios in future will directly affect the operation safety and power generation dispatch of cascade reservoirs.Therefore,it is necessary to study the impact of climate change on the runoff of Yalong River basin.Firstly,the the monthly SWAT model of the watershed is established,then the meteorological data of each station is predicted by using SDSM from 2006 to 2100.Finally,the future runoff of Yalong River basin is simulated by using the calibrated SWAT model from 2006 to 2100.The results show that the runoff of Yalong River will increase in the future,and increase synchronously with the enhancement of radiation forcing.The annual average runoff growth rates of RCP2.6,RCP4.5 and RCP8.5 are 8.9%,12.5%and 16.7%respectively,and the annual runoff of 2020S,2050S and 2080S under three RCPs shows different trends.Under the RCP2.6,it increases gradually to the peak value and then decreases slightly.Under the RCP4.5,it increases gradually to the peak value and then stabilizes.While under the RCP8.5,it increases continuously.In terms of annual distribution of runoff,the proportion of runoff in flood season under three RCPs decreases first and then increases in the three periods of 2020S,2050S and 2080S.The overall trend in the whole forecast period is decreasing.Under the RCP2.6,RCP4.5 and RCP8.5 concentration paths,the mean proportion of the whole forecast period decreases from 75.9%of the base period to 72.9%,72.0%and 71.2%,respectively.The increase of runoff will have a greater impact on the flood characteristics of the basin.Therefore,the designed flood in the basin should be revised and flood control dispatching schemes adjusted to reduce the operational risk of cascade reservoirs and to improve the efficiency of power generation dispatching in the Yalong River basin due to climate change.