Bed morphology and generation of step–pool channels
Bed morphology and generation of step–pool channels
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DOI：
10.1002/esp.1639
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发表时间：
2008-10
影响因子：
3.3
通讯作者：
R. Weichert;G. R. Bezzola;H. Minor
中科院分区：
文献类型：
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作者：
R. Weichert;G. R. Bezzola;H. Minor
通过水槽试验，研究了阶跃式深槽的形成过程和河床形态。从实验中可以区分不同的步骤类型和步骤配置取决于流功率。这些阶跃类型可以看作是阶跃-池系统生成机制的一个形象。这些结果表明，床粗糙度的几何形状发展的条件，提供了最大可能的床稳定性为一个给定的粒度分布。与其他各种研究相反，逆行沙丘并没有对台阶结构的产生做出贡献。然而，本研究的数据很好地符合肯尼迪提出的砂床河流的反沙丘形成区域。这一观察结果指出，位于肯尼迪地区的阶梯-池场数据并不一定证明逆行沙丘在阶梯发展中发挥了作用。相反，有人提出，在肯尼迪地区的反沙丘形成存在水力条件下，流动阻力最大化。有人认为，这种最大流动阻力与床形及其高度之间的最佳距离有关，而与这些是砂卵石床河流中的逆行沙丘还是巨石床河流中的阶梯池单元无关。对反沙丘形成的Kennedy区域的考虑和对平面形状台阶类型（取决于水流功率）的分析均表明，通过将台阶-水池结构向提供最大流动阻力和最大河床稳定性的几何形状修改，陡峭的河道具有自稳定的潜力。版权所有© 2008约翰威利父子有限公司。
Flume experiments have been carried out to study the formation processes and the bed morphology of step–pool channels. From the experiments different step types and step configurations could be distinguished depending on the stream power. These step types can be seen as an image of the generation mechanisms of step–pool systems. These results suggest that the bed roughness geometry develops towards a condition that provides the maximum possible bed stability for a given grain size distribution. In contrast to a variety of other studies, antidunes did not contribute to the generation of the step structures. However, the data of the presented study fits well into the region of antidune formation proposed by Kennedy for sand‐bed rivers. This observation points out that step–pool field‐data located in the Kennedy region do not inevitably prove that antidunes played a role in step development. It is rather proposed that in Kennedy's region of antidune formation there exist hydraulic conditions where the flow resistance is maximized. It is suggested that such maximum flow resistance is associated with an optimal distance between the bedforms and their height, independently of whether these are antidunes in sand‐ and gravel‐bed rivers or step–pool units in boulder‐bed streams. The considerations of the Kennedy region of antidune formation and the analysis of planform step types depending on stream power both suggest that steep channels have a potential for self‐stabilization by modifying the step–pool structure towards a geometry that provides maximum flow resistance and maximum bed stability. Copyright © 2008 John Wiley & Sons, Ltd.