黄河下游防洪形势变化与治理前景展望

The change and prospect of flood control situation in the Lower Yellow River

实测资料表明,黄河中上游干支流治理已经使下游的防洪形势发生变化,洪峰流量和年沙量大幅度减少,小浪底水库投入运用15年,下游河槽发生强烈冲刷,水位下降超过2m,生产堤的存在已经使22 000m3/s的设计洪水在花园口河段不漫滩,其防洪设计标准千年一遇。无论黄河水沙如何变化,都要经过小浪底水库调节进入下游,黄河窄深河槽具有极强的泄洪输沙能力。分析研究表明,小浪底水库进行多年调沙,相机利用洪水排沙,可长期发挥作用;下游游荡河段通过双岸整治形成高效排洪输沙通道输沙入海,继续冲刷河槽,可实现河床不抬高。建议修建桃花峪水库控制下游大洪水,并进一步纵向冲深河槽。

Field data show that the regulation of the upper and middle reach of the Yellow River created irreversible changes on the downstream flood protection situations,including significant decreased peak flood discharges and annual sediment yield. After the operation of Xiaolangdi Reservoir for 15 years,strong scour occurred and drawdown of water surface elevation has reached about 2 meters. The existence of the production dike makes it possible for flood with design discharge of 22,000m^3/ s to be non- overtopping on the floodplain at Huayuankou reach. The design period of the flood protection standard becomes 1000- year. No matter how the flow and sediment may vary,they are regulated by Xiaolangdi Reservoir before entering the lower reach.The narrow and deep channel has strong flood discharges and sediment transport capacity. Research results have shown that,multi- year sediment regulation by Xiaolangdi Reservoir,and sediment release at the right time by flood,can enhance the long term function of the reservoir. For the lower reach,a couple banks can be used to form an efficient flood discharge and sediment transport corridor to further erode the channel bed. Plan for construction of the Taohuayu Reservoir is also proposed to control large flood events and scour of the river bed.