摘要:
通过评估IPCC第四次评估公开发布的22个全球气候模式对长江流域降水和气温的模拟性能,选取了BC-CR-BCM2.0等7个气候模式,利用这些GCM s在A1B、A2和B1三种典型排放情景下的未来气温和降水预测结果,结合BP神经网络模型,在对模型验证效果良好的基础上,预测未来气候变化下长江流域径流变化趋势.结果表明,长江流域未来年平均径流量呈减少趋势,宜昌水文站以枯水年减少为主,未来年平均流量比历史年平均流量减少了520 m3/s;大通水文站则以平水年减少为主,比历史年平均流量减少了250 m3/s,水量的减少对南水北调东中线的调水规模和调配、管理提出了较大的挑战.长江流域多年平均月流量增加将主要发生在1~6月,而7~12月将以减少趋势为主.宜昌站和大通站的1~6月份平均增加幅度分别为29.6%和13.8%,7~12月份的平均减少幅度分别为-18.2%和-11.0%,宜昌站的变幅要高于大通站.宜昌站汛期呈减少趋势,平均为-8.5%,非汛期略有增加.大通站变化趋势与宜昌站相反,汛期呈增加趋势,平均为2.3%,非汛期略有减少.
Abstract:
The performance of twenty-two General Circulation Models(CCMs)in simulating precipitation and temperature are evaluated and validated in the Yangtze River basin.Simulations of these CCMs were used in the IPCC Fourth Assessment Report(AR4).The Bjerknes Center for Climate Research(BCCR)Bergen Climate Model (BCM)2.0,or BCCR_BCM2.0,and other six CCMs stand out from the twenty-two evaluated CCMs.Using an artificial neural network and climate changs projections from the selected seven CCMs under A1 B,A2 and B1 scenarios, the hydrological response to future climate changs in the Yangtze River basin is studied.The projective on the subject is presented.The result shows that there could be a decreasing trend in the mean annual streamflow in the future.At the Yichang station,a dry year condition would be likely to become more common in a warmer world.The reduction of mean annual streamflew could reach as much as 520 m3/s for dry years,while such a reduction would be 250 m3/s for a normal year at the Datong station.The decrease in available water could be a bid challenge to the practice of water allocation and management in the western and central routes of the South-to-North Diversion project.The mean monthly streamflow would be projected to be increasing during January to June,while,the opposite should be true during the second half of the year.At Yichang and Datong,the streamflow increases would be 29.6% and 13.8% during,Tanuary to,Tune and decreases could reach as much as-18.2% and-11% during the second half of the year,respectively.The variation of streamflow could he expected to be larger at Yichang than at Datong.During flooding seasons,there would be a decrease of-8.5% in Yichang streamflow,and a slight incerease for other reasons.In contrast,the Datong streamflow would have a 2.3% increase during flooding seasons,and a slight decrease in non-flooding seasons.
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