枢纽下游河床极限冲刷及水位降落研究进展

Research progress on riverbed ultimate erosion and falling of water level at lower reach of hydro-junction

天然河流修建枢纽后,上游来沙将在枢纽形成的水库内淤积,出库沙量锐减,下游河道因受枢纽下泄清水的冲刷而发生一系列变化。特别是对于沙质和沙卵石河床,随着下泄清水的冲刷,河床随之出现了相应的再造床过程。枢纽清水下泄引起下游河床下切、水位下降问题是枢纽设计及航道整治中的重点和难点。由于河段来水来沙条件、枢纽调度方式、坝下河床断面型态、河床质组成及覆盖层厚度等不同,坝下形成的冲刷幅度、稳定冲刷层及冲刷范围等各不相同,坝下水位降落幅度也不尽相同,而河床质组成是影响河床极限冲刷的主要因素。文章从不同河床质组成出发,分别对枢纽下游河床极限冲刷以及水位下降研究成果进行了总结,并对各种计算方法进行了简要的评述。

The erosion of released clear water from reservoir will cause a series of changes of downstream fiver course, especially for sandy riverbed and gravel riverbed. Riverbed downcutting and falling of water level at lower reach of hydro-junction resulting from release of clear water is the emphasis and difficulty in junction design and waterway regu- lation. Since conditions including incoming water and sediment, hub scheduling mode, cross section form of riverbed, riverbed materials and cover thickness are various, erosion depth, stable erosion layer and erosion range are different from each other. However, river bed material is the main factor influencing erosion depth. According to different riverbed materials, research results on riverbed ultimate erosion and falling of water level at lower reach of hydro-junction are summa- rized and various calculation methods are commented in this paper.