黄河下游水沙变异与河道响应

对龙羊峡、刘家峡和三门峡3座水库修建后黄河下游的水沙变异与河道响应情况进行了分析,认为:①三门峡水库运用后,汛期下泄水量占全年的比例平均为45%,和天然情况相比减少了15%,排沙量更为集中(占全年的95%以上),和天然情况相比增大了10%左右,水沙更趋不平衡;②汛期洪水减少,洪峰流量和洪峰期水量减小,含沙量增大,形成小水带大沙;③洪水的造床作用明显减弱,使得河流平面尺度和断面尺度减小,河床冲淤演变所涉及的范围有所减小,河道的淤积更加局限在中水河槽内,主槽和嫩滩的淤积导致了“二级悬河”的发育和发展。建议在现有水库对水量实行调节的同时,尽快修建中游泥沙调节水库,实现黄河水沙的统一调控,创造比较和谐的水沙关系,维持黄河健康生命。

Silt-Discharge Variation and Channel Response of the Lower Yellow River

The paper analyzes the silt-discharge variation and channel response of the lower Yellow River after completion of the three reservoirs of Longyangxia,Liujiaxia and Sanmenxia.It concludes that a) after putting into operation of Sanmenxia Reservoir,the discharge of flood season averages about 45% of the whole year proportion,reducing 15% comparing with the natural condition and the sediment ejection is more concentrated(more than 95% of the whole year),increasing about 10% comparing with the natural condition.The silt-discharge trends even more unbalanced;b) Flood is reduced in flood season,both the peak discharge and volume in peak period reduced and sediment concentration increased,forming heavy sediment with less runoff and;c) the function of bed-building of floods is notably weaken,reducing the river plane scale and section scale,reducing the effected range of scoring and deposition evolution to some extent,the channel deposition more concentrated in normal channel and the deposition of the main channel and newly formed floodplain resulted in the development of "secondary elevated river".It suggests building a sediment regulation reservoir on the middle Yellow River while regulating water by existing reservoirs,achieving integrated regulation and control of the Yellow River silt-discharge,creating relative harmonious silt-discharge relationship and keeping the healthy life of the Yellow River.