Why some alluvial rivers develop an anabranching pattern
Why some alluvial rivers develop an anabranching pattern
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DOI：
10.1029/2006wr005223
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发表时间：
2007-07-24
影响因子：
5.4
通讯作者：
Nanson, Gerald C.
中科院分区：
文献类型：
--
作者：
Huang, He Qing;Nanson, Gerald C.
[1]再分支河流已经在全球范围内得到了确认，但对其发生的广泛接受和令人信服的理论解释仍然难以捉摸。利用基本的水流输沙关系，本研究分析了自调节冲积河道可以形成分支以改变其水流效率（单位水流功率的输沙能力）的机制。它表明，在不调整渠道坡度，渠道数量的增加可以产生成比例的流量效率下降，特别是在一些辫状河的能源消耗的理解相关的发现。然而，再分支效率可以显着增加减少通道宽度，发生时，植被冲积岛屿或通道间的山脊形成。宽度减小和渠道数量增加的抵消作用可能导致在不调整坡度的情况下，一个原本不稳定的系统（欠载或超载）实现稳定。与其他河流模式一样，再分支可以用稳定平衡或增生不平衡的例子来描述。
[1] Anabranching rivers have been identified globally, but a widely accepted and convincing theoretical explanation for their occurrence has remained elusive. Using basic flow and sediment transport relations, this study analyzes the mechanisms whereby self-adjusting alluvial channels can anabranch to alter their flow efficiency ( sediment transport capacity per unit of stream power). It shows that without adjusting channel slope, an increase in the number of channels can produce a proportional decrease in flow efficiency, a finding particularly relevant to understanding energy consumption in some braided rivers. However, anabranching efficiency can be significantly increased by a reduction in channel width, as occurs when vegetated alluvial islands or between-channel ridges form. The counteracting effects of width reduction and an increasing number of channels can cause, with no adjustment to slope, an otherwise unstable system (underloaded or overloaded) to achieve stability. As with other river patterns, anabranching can be characterized by stable equilibrium or accreting disequilibrium examples.