Morphological bedload transport rates

河流以推移质的形式输送部分泥沙--较大的颗粒在河床上沿着滚动或弹跳。推移质对河流的形态和动力学非常重要，因为它的时空变化率是直接负责的功能，如池，酒吧和岛屿，这是许多河流的地貌的主要元素的形成。同样，推移质过程影响河流动力学，如河道迁移和形态变化率。这项研究的目的是有助于了解控制推移质通量的变量，特别是颗粒运动的方式与河流迁移和改变其形态的形态相互作用。我们的目标是描述河流形态的发展作为粒子传输过程的结果。这是了解河流动力学的基础，并直接应用于减轻侵蚀问题，了解河流过程和流量对河流栖息地的影响，以及恢复工程改变的河流。在野外很难测量河床颗粒的运动，但是对于砾石层河流，许多过程和特征可以在实验室水槽中的小比例物理模型中重现。我们将使用物理模型来研究各种流动条件和不同通道形态下对床颗粒动力学（侵蚀/沉积频率和运输距离）的控制，以了解形态特征如何从颗粒路径和路径长度发展，进而约束这些运动。我们将使用示踪颗粒和摄像机测量颗粒运动，并使用数字摄影测量和图像处理来获得河床地形，地形随时间的变化以及河床粗糙度和颗粒尺寸数据。推移质输移可能完全与河流的沙洲和水池的动力学有关，而不是在这些特征上自由移动（通常认为是这样）。如果是这样的话，这将创造一个全新的概念和理论图片推移质输运过程和河道动力学。

Rivers transport part of their sediment load as bed load - the larger particles that move by rolling or bouncing along the river bed. Bed load is important to river morphology and dynamics because its spatial and temporal variation in rate is directly responsible for the formation of the features, such as pools, bars and islands, which are major elements of the geomorphology of many rivers. Similarly, bed load processes affect river dynamics, such as channel migration and rates of morphological change. This research is intended to contribute to understanding the variables that control bed load flux and, in particular, the way in which particle movement interacts with the morphology as the river migrates and changes its morphology. The goal is to describe the development of river morphology as the outcome of the particle transfer process. This is fundamental to understanding river dynamics and has direct application in mitigating erosion problems, understanding the effects of river processes and flow on in-stream habitat and in restoring rivers altered by engineering. It is difficult to measure the bed particle movement in the field but for gravel-bedded rivers many of the processes and features can be reproduced in small-scale physical models in a laboratory flume. We will use physical models to investigate the controls on bed particle dynamics (erosion/deposition frequency and transport distances) under various flow conditions and different channel morphologies to understand how the morphological features develop from the particle pathways and path lengths and, in turn, constrain those movements. We will measure particle movement using tracer particles and video cameras and use digital photogrammetry and image processing to derive river bed topography, topographic change over time and bed roughness and particle size data. It is possible that bed load transport is completely tied up in the dynamics of the bars and pools of the river rather than moving freely over those features ( as it is often conceived). If so, this creates an entirely new conceptual and theoretical picture of bed load transport processes and river channel dynamics.