水库下游非平衡河流设计最低通航水位的确定

Study on the design of lowest navigable water level downstream dams

设计最低通航水位是航道整治工程的基本参数,该水位的现有确定方法是建立在河床冲淤变化不大条件下的水文资料统计方法。水库下游河床处于非平衡变化过程中,河床冲淤幅度较大或水库下泄流量过程因调度规则的差异而不同时,已有方法不再具备适用条件。本文将原有平衡河流通航设计水位的概念延伸至水库下游非平衡河流河床冲淤变化过程中,分析了三峡水库不同蓄水时段影响设计水位的主要因素、影响过程及其程度,以水库调度计算和下游河床冲淤一维数学模型计算为基础,分析了长江中下游沿程各站不同时期的设计水位,又为水库下游非平衡河流设计最低通航水位确定提供方法参考。

Design lowest navigable water level is a very important parameter to navigation engineering. The existing methods to decide design water level are on the base of hydrology data statistic with small river bed change. The river bed downstream dam is under the non-equilibrium condition because the river bed and the discharge process downstream dam would have changed. With extending the concept of design water level from the equilibrium river to the non-equilibrium river, the design water level line method is proposed on the basis of the flood routing through reservoir and one dimension numerical model for channel bed variation. As an example, the design water level change line is figured out downstream the Three George Project and the reasons are analyzed.