三峡运行对长江入海流量及上海城市供水的影响

Impacts of Three Gorges project on the Yangtze River's discharge into the sea and the water supply in Shanghai

三峡的运行使长江入海流量发生变化,从而对长江口的咸潮入侵及上海市长江口水源地的供水产生一定影响。本文收集了大量实测资料,对大通～徐六泾流量关系进行分析,在此基础上,采用统计分析法和数学模型计算等手段定量分析了三峡试运行期和今后正常运行期对入海流量及上海市长江口水源地的影响。分析结果表明:目前在10月至翌年4月,大通流量基本可代表入海流量;总体而言,2003-2008年三峡的运行对长江入海流量影响不大;三峡按照优化的调度方式运行后,在枯水年份的1-3月,入海流量将增加2000m3/s左右,有利于压制河口咸潮,但在上游来水特枯的情况下,长江口水源地最长连续不宜取水天数仍会超过10天,上海城市供水仍存在一定的隐忧。

Operation of the Three Gorges project（TGP） causes changes in the Yangtze River＇s natural discharge into the sea,and consequently produces impacts on the saltwater intrusion to the Yangtze estuary and the reservoir water supply in Shanghai.This paper first studies the relationship between discharges at Datong（DT） and Xuliujing（XLJ） stations,using tremendous field data,and then adopts statistical methods and numerical simulation to make a quantitative analysis of these impacts at two TCP stages,recent test run and normal operation in the future.Results show that at the test-run stage,from October to the next April,the flow at Datong can well represent the Yangtze＇s discharge into the sea,and in 2003-2008 generally this flow was influenced little by the TGP operation.If at the future stage TGP is operated by the optimized scheduling,the discharge into the sea from January to March in a dry year will increase roughly by 2000m3/s,favorable to restraining the saltwater intrusion.Under the conditions of extremely low river flow,however,the reservoir＇s longest consecutive period unsuitable for water intake will still exceed 10 days,and hence the water supply safety of the city will be affected.