Controls and limits on bedrock channel geometry
Controls and limits on bedrock channel geometry
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基岩河道几何形状的控制和限制
DOI：
10.1029/2009jf001601
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发表时间：
2010
影响因子：
--
通讯作者：
G. Tucker
中科院分区：
文献类型：
--
作者：
B. Yanites;G. Tucker
[1]自然切割基岩河流中的通道几何数据揭示了通道宽度、坡度和侵蚀速率之间的可变关系。为了解释这些参数之间的关系范围，我们提出了一个优化的通道几何模型。该模型再现了以前的理论和数值模拟的比例关系，但是，解释现场数据，该模型必须纳入不动的沉积物覆盖，降低垂直切割效率的影响。对于给定的基准面下降速率，向系统中添加沉积物既会使河道变宽又会使河道变陡。我们还发现，一个恒定的宽度与深度的比例是唯一有效的流所需的剪切应力泥沙运输是微不足道的相比，所需的剪切侵蚀在所施加的基准面下降。我们的模型提供了一个看似矛盾的现场观察控制通道宽度的解释，并表明，通道宽度从根本上控制河流的侵蚀潜力，特别是当它进行了显着的推移质。
[1] Data on channel geometry in naturally incising bedrock rivers reveal variable relationships between channel width, slope, and erosion rate. To explain the range of relationships between these parameters, we propose an optimized channel geometry model. The model reproduces previous theoretical and numerical modeling scaling relationships; however, to explain the field data, the model must incorporate the effects of immobile sediment cover that reduces vertical incision efficiency. Adding sediment to a system for a given rate of base level fall both widens and steepens the channel. We also find that a constant width to depth ratio is only valid for streams where the shear stress required for sediment transport is insignificant compared to the shear required to erode at the imposed base level fall. Our model offers an explanation of seemingly contradictory field observations of controls on channel width and shows that channel width fundamentally controls the erosive potential of a river especially when it carries a significant bed load.