黄河下游洪峰增值机理与验证

Mechanism of flood peak increase along the lower Yellow River and its verification

针对黄河下游“04.8”洪水出现的洪峰异常增值现象,探讨了洪峰增值的水动力学机理,认为小浪底水库异重流排出的极细高含沙洪水在下游河道输移的过程中,引起河道糙率变小,是造成洪峰异常增值的根本原因。而后采用能够合理反映含沙量及泥沙级配变化对河道糙率影响的黄河河道准二维水沙数学模型,对此洪水进行的模拟,验证了上述观点。同时指出河道糙率变小引起的洪峰增值对黄河下游防洪安全可能造成的危害,应引起有关部门的高度重视。

The paper studies the abnormal phenomenon that a flood peak increased in August. 2004 along the lower Yellow River and its hydrodynamic mechanism. It is found that the flood peak increase was mainly due to decrease of channel roughness in the propagation of high-concentrated flood carrying extra fine sediment which was discharged from Xiaolangdi reservoir. The mechanism of this flood is verified by the simulation with a quasi-2-D numerical model, which includes, among others, roughness change due to concentration and sediment size gradation. It is pointed out that the flood peak increase due to roughness reduction may endanger the security of flood control works along the lower Yellow River, so that attention must be pay to this problem.