The Dynamics of Channel Slope, Width, and Sediment in Actively Eroding Bedrock River Systems
The Dynamics of Channel Slope, Width, and Sediment in Actively Eroding Bedrock River Systems
复制标题
DOI：
10.1029/2017jf004405
复制
发表时间：
2018-07
期刊：
影响因子：
--
通讯作者：
B. Yanites
中科院分区：
文献类型：
--
作者：
B. Yanites
侵蚀景观中河流的演化在决定景观起伏和调节气候-构造相互作用方面发挥着关键作用。量化河流系统演化的常用方法是使用一维、分离限制的河流功率方程。该模型的一个潜在缺点是它没有考虑河道宽度变化的影响或沉积物输送动力学的作用。在这里，我提出了一种新方法来模拟河道宽度对河流动力学的影响，以探索宽度变化和泥沙输送如何影响河流剖面演变。通过这种方法，垂直河流侵蚀可以基于任意数量的河流侵蚀模型进行操作，例如简单的剪切应力模型（例如，脱离限制）、沉积物覆盖-剪切应力混合模型或机械跃移-磨损模型。我探讨了这三个模型对岩石抬升率增加（即 2、3、5、10 和 20 倍增加）的敏感性。一般来说，结果表明，结合河道宽度调整或泥沙输运动力学会降低河流剖面对岩石抬升率的敏感性。对于依赖沉积物输运的模型，敏感程度取决于系统是否受到基岩暴露或侵蚀潜力（即脱离潜力）的限制。该方法产生的瞬态响应揭示了不同的宽度和坡度模式，这可能为了解一个地区基岩侵蚀的限制物理机制提供有价值的见解。这项工作的影响是广泛的，包括将潜在的侵蚀控制与宽度和坡度的现场观测区分开来的潜力，以及理解气候-构造相互作用。
The evolution of rivers in eroding landscapes plays a key role in determining landscape relief and modulating climate‐tectonic interactions. A common approach to quantifying river system evolution uses a one‐dimensional, detachment‐limited stream power equation. One potential drawback of this model is that it does not incorporate the effects of changes in channel width or the role of sediment transport dynamics. Here I present a new method for modeling the influence of channel width on river dynamics to explore how variable width and sediment transport impact river profile evolution. With this approach, vertical river erosion can operate based on any number of river erosion models, such as a simple shear stress model (e.g., detachment limited), sediment cover‐shear stress hybrid models, or mechanistic saltation‐abrasion models. I explore the sensitivity of these three models to increases in rock‐uplift rate (i.e., 2, 3, 5, 10, and 20× increase). Generally, the results show that incorporating channel width adjustment or sediment transport dynamics lowers the sensitivity of a river profile to rock‐uplift rate. For the sediment transport‐dependent models, the degree of sensitivity depends on whether the system is limited by bedrock exposure or erosion potential (i.e., detachment potential). The approach produces transient responses that reveal distinct patterns of width and slope, which may provide valuable insight into the limiting physical mechanisms of bedrock erosion in a region. The implications of the work are broad and include the potential to distinguish underlying erosion controls from field observations of width and slope as well as understanding climate‐tectonic interactions.