山区河流河床波的动态传播与调整机理

山区河流受来沙突增影响发生淤积，河床纵剖面相对其原始形态发生波状起伏，当泥沙离开这一河段时河床冲刷，纵剖面波形变化。大量泥沙输往下游，下游河床也发生先淤积后冲刷的演变过程，这种河床宏观波动像扰动一样向下游传播，称为河床波（bed wave或sediment slug/wave）。目前关于河床波动态传播与调整的物理机理尚不明确。本项目拟采用实测资料分析、水槽试验和理论研究的方法，结合河床演变的滞后响应模型，分析来沙突增影响下河床波的几何形态变化和动态传播特征，研究影响河床波耗散与迁移特性的驱动因子，探讨横向泥沙交换、深槽—浅滩形态及前期水沙条件等对河床波传播的影响，建立河床波耗散与迁移特征量与主要影响因子的定量关系，提出河床波传播的概化模式，建立模拟长时空尺度下的河床波传播的计算方法。研究成果可为流域侵蚀严重区域或震后河流的修复提供参考。

Massive sediment input to a gravel bed river often causes deposition and the channel longitudinal profile will form a wave compared to its initial shape. As the sediment moves downstream, erosion occurs and the downstream reaches show similar evolution processes, i.e. deposition first and erosion later, resulting in the deformation of the wave-shape of the longitudinal profile. This large scale wave-like fluctuation of channel bed evolves like a downstream moving disturbance, and is herein called bed wave (or sediment slug/wave). Thus far, the physical mechanism of bed wave is not clear. This project aims to study the bed wave by case studies, flume experiments, theoretical analysis, and the Delayed Response Model. We will analyze the characteristics of the geometry adjustment and dynamic propagation of the bed wave, identify the impact factors of the dispersion and translation of bed wave, investigate the impacts of lateral sediment exchange, pool-riffle and previous conditions on the bed wave movement, propose a generalized physical model and a calculation method for its long-term and large scale evolution. The research results may help inform river restoration in areas with severe basin erosion or post-earthquakes.