长江上游岷江流域水沙变化特征分析

Analysis of flow and sediment variation features of the Minjiang River Basin in the upstream Yangtze River

岷江流域来水来沙过程对三峡水利枢纽工程的正常运行具有较大的影响。通过资料分析,初步认为该流域水沙年际变化主要为:岷江干流段水量变幅不大,沙量在彭山以上地区、彭山—五通桥及以下区域呈减少趋势;而其支流青衣江上游、大渡河上游水量有所减少,但沙量有所增加,来沙量占流域沙量的65%左右,但随着青衣江和大渡河的逐步开发,水利水电工程拦沙作用将逐渐增大,以致岷江彭山—五通桥区间段来沙量将来会有所减少。根据岷江流域主要测站资料分析,并结合流域内水库(水电站)建设情况,除降雨变化可能引起个别年份输沙量有所增加外,岷江高场站水沙关系1991年前无明显变化,但近期水沙关系发生明显变化,较其它年代同水量下沙量相对减小,其减沙原因主要是流域降雨条件变化及水库拦沙作用。

The flow and sediment of the Minjiang River has important influence on the normal operation of Three Gorges Project. Through data analysis, it is concluded that the main annual variation of flow and sediment of the Basin are: flow volume of the main stream of the Minjiang River is not obvious, the sediment in the upstream area of Pengshan, the area between Pengshan and Wutongqiao as well as the downstream area show a reduce tendency; in the upstream of the tributary Qingyi River, the Dadu River, the flow volume reduces and sediment volume increases, the sediment reaches 65% of the total basin. Along with the development of the Qingyi River and the Dadu River, the sediment retaining of the water conservancy and hydropower projects will gradually increase, the flow and sediment volumes in the area between Pengshan and Wutong qiao will decrease. According to the data analysis of the main measurement stations in the Minjiang Basin and in the combination of reservoir (hydropower station)construction condition in the basin, except in individual year, the sediment transportation increase due to precipitation variation, the flow and sediment relation at Gaochang station on the Minjiang River has no obviously change before and after 1991, but in recent years, the sediment volume relatively reduces compared with that of the other years, the cause of sediment reduction are precipitation condition variation in the Basin and sediment retaining of the reservoir.