大规模采沙对弯道滩险的影响

以岷江朱石滩为例,分析大规模采沙对弯道滩险河床演变和航道条件的影响。采沙前,朱石滩河段河床基本冲淤平衡;采沙后,河床冲淤平衡被破坏,河床严重下切,汛期河床回淤剧烈。大规模采沙对弯道滩险航道条件的影响主要表现为破坏航道边界、降低河段水位、增加上游水面比降;原来稳定的弯槽由于水深不足而被舍弃,航道改走不稳定的直槽,给航道维护带来困难;河床地形凌乱,航槽局部存在较大横流,给船舶航行带来安全隐患。

Impacts of large-scale sand dredging on rapids at curved channel

Taking Zhushi rapids in the Minjiang river for example,we analyze the impacts of large-scale sand dredging on the riverbed evolution and channel conditions of rapids at the curved channel.The riverbed erosion of Zhushi rapids maintained a balance before the sand dredging.The riverbed erosion balance was destroyed and the riverbed dropped severely after the sand dredging.The severe siltation happened from the upstream to the downstream in the flood season.The impacts of large-scale sand dredging on the channel conditions are destroying channel boundary,reducing river water level,increasing upstream water surface slope,etc.The original stable curved channel was abandoned due to the lack of water depth.Waterway changed to go unstable straight channel,which created difficulties for the channel maintenance.Sand dredging also resulted in disordering of riverbed topography and big cross-flow in waterway,which is dangerous for the ships sailing.