河床演变的均衡稳定理论及其在黄河下游的应用

Regime theory on river bed evolution and its application in the Lower Yellow River

在系统分析有关河床演变均衡稳定理论的研究成果基础上,指出河流熵理论的最小可用能耗率原理及其表达式完整地表达了冲积河流河床演变的自动调整作用基本原理,应用河流最小可用能耗率原理的表达式封闭河床演变方程组,建立河床演变均衡稳定数学模型,应用该模型计算了黄河下游各河段在不同水沙条件下的河槽均衡稳定断面,并计算分析了小浪底水库下游的清水冲刷、拦粗排细和水温变化及涨冲落淤等因素对河槽均衡稳定的影响,分析了河道输水输沙优化的临界指标,提出了强化非恒定流调水调沙、调控60-100 kg/m3的不利来水含沙量和以滞洪拦粗排细运用为主等改善小浪底水库运用的措施。

Based on the systemic analysis of theories about riverbed evolution in regime,the principle and formula for minimum rate of available energy dissipation deduced from theory of fluvial entropy is considered to completely express the basic principle of automatic regulation about riverbed evolution of alluvial river. A mathematic model of riverbed evolution in regime was developed with the formula for minimum rate of available energy dissipation to close the equations of riverbed evolution. The model was applied to compute the channei sections in regime under various conditions of flow and sediment in the Lower Yellow River, and the influences were calculated and analyzed for several factors, such as scour of clear flow released from Xiaolangdi reservoir, detaining coarse sediment and releasing fine sediment by the reservoir, change of water temperature, scour at flood rising and siltation at flood recession. Based on analyses of critical indexes for optimal transport of water and sediment, the measures to improve the management of Xiaolangdi reservoir were presented, which include the regulation of unsteady flow, control of the disadvantage sediment concentration of 60 - 100kg/m^3 , and storing coarse sediment by flood detention.