Unsteady numerical modeling of river hydraulics and morphology changes

泥沙输移模型广泛应用于河流水力学中，例如用于评估 确定大坝下游的风险区域。现有的泥沙输移关系假定为稳态水力学。在许多可能发生泥沙运动的实际情况下，水力状态是非常不稳定的。流动不稳定性引入了现有的“稳定流动”关系所没有考虑的动态效应，其可能具有戏剧性的影响，例如卡特里娜飓风对新奥尔良的灾难性影响、1997年沿着北达科他州、明尼苏达州和南马尼托巴的红河的红河洪水以及1996年萨格内的暴雨。 此外，只有一些地方河流恢复行动发生后，这样的洪水：当地的银行稳定，当地的泥沙清除。任何重建自我维持的自然系统的尝试都需要了解特定河流的地貌过程，以及这些过程如何得到当前（或未来）水流状况的支持。 我们的目标是开发一个综合的河流河岸走廊的方法，结合流域尺度分析，用于评估拟议的走廊修复设计的长期有效性。 这种新的方法是一个迫切需要的水利工程师，河流地貌学家，景观设计师和河流生态学家参与河流恢复项目。这些项目通常面临的挑战是缺乏综合设计工具来评估重建河流走廊的长期稳定性。

Sediment transport modelling is widely used in fluvial hydraulics, such as for the assessment of the determination of risk areas downstream of a dam. Existing sediment transport relationships assume steady state hydraulics. In many practical situations, in which sediment movement is likely, the hydraulic state is very unsteady. Flow unsteadiness introduces dynamic effects not accounted for by existing "steady flow" relationships which can have dramatic effects such as the catastrophic effect of Hurricane Katrina on New Orleans, the Red River Flood of 1997 along the Red River in North Dakota, Minnesota, and Southern Manitoba and the downpours of the Saguenay in 1996. Moreover, only some local stream restoration actions take place after such floods: local bank stabilization, local sediment removal.... Any attempt to recreate a self-sustaining natural system requires an understanding of the geomorphic processes that characterize a certain river and how these processes can be supported by present (or future) flow regimes. Our goal is to develop an integrated stream-riparian corridor approach to be used in conjunction with watershed-scale analysis, for evaluating the long-term effectiveness of proposed corridor rehabilitation designs. This new approach is a critical need for hydraulic engineers, fluvial geomorphologists, landscape architects, and stream ecologists involved in stream rehabilitation projects. These projects are usually challenged by the lack of integrated design tools to evaluate the long-term stability of reconstructed stream corridors.