淤滩与刷槽之间没有必然的联系

实测资料与动床摸型试验均表明,在洪水过程中淤滩与刷槽虽然同时发生,但它们之间并没有必然的联系。在多沙河流上洪水漫滩必然会造成滩地淤积,并在滩唇形成自然堤,阻断滩槽水流交换;主槽的冲刷发生在涨水期,在落水期不管含沙量大小,河床均处于淤积状态。漫滩后的清水在滩地上流动缓慢,远远小于主槽水流的运动速度,因此漫滩水往往在落水期才能汇入主槽,且只能起到减少主槽淤积的作用,无法改变由于洪水的非恒定性形成的落水期河床必然淤积的状态。实测资料表明,含沙量100~200 kg/m3的不漫滩洪水在涨水期仍可造成主槽的强烈冲刷。

No Inexorable Relationship between Silted Floodplain and Scoured Channel

It is shown both by the observed data and mobile-bed model testing that although scour channel and depositional floodplain happen at the same time during flooding,there is no inexorable relationship between them.Flooding will inevitably cause deposited floodplain,form a natural dyke at the fringe of floodplain and stop flow of floodplain and channel exchange for a hyper-sediment concentrated river.The main channel is scoured in rise and the riverbed is deposited no matter the sediment concentration high or low in falling period.The clear water on the flooded floodplain flows much slower than that in the main channel.Thus,usually the overbank flow could flow into the main channel during falling period and only have the function of reducing the deposition in the main channel.It is unable to change the statement of inevitable deposition of the riverbed in falling period due to non-steady floods.The observed data shows that non-bankfull flood with 100~200 kg/m~3 sediment concentration still can seriously scour the main channel during rise.