How long is a hillslope?
How long is a hillslope?
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DOI：
10.1002/esp.3884
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发表时间：
2016-06-30
影响因子：
3.3
通讯作者：
Hurst, Martin D.
中科院分区：
文献类型：
--
作者：
Grieve, Stuart W. D.;Mudd, Simon M.;Hurst, Martin D.
山坡长度是景观的基本属性，与排水密度、滑坡危害、生物地球化学循环和山坡沉积物运输有着内在联系。现有的估算集水区平均山坡长度的方法包括排水密度的反演或坡区尺度变换的断裂识别，其中山坡域过渡到河流域。在这里，我们实现了一种技术，该技术基于使用像素方向计算的流量方向，在数字高程模型（DEM）中对山顶点源的流量进行建模，直到到达使用最近开发的通道提取算法定义的通道网络。通过这些测量技术之间的比较，我们表明，从地形坡度与排水面积的关系中估计山坡长度，或通过排水密度的反演措施，系统地低估了山坡长度。此外，坡面积尺度破碎估算的坡长在相似形态和面积的集水区之间存在较大差异。然后，我们利用景观的山坡长度-地形结构来探索在景观上运行的沉积物通量的性质。不同的地形形式预测了端部泥沙通量定律，这些定律约束了斜坡上的泥沙输运，它们线性或非线性地依赖于斜坡坡度。由于我们的方法是从DEM中的每个山脊顶像素提取山坡剖面，因此我们表明，所得的山坡长度起伏测量结果可用于区分土壤覆盖景观中的线性和非线性泥沙输送规律。我们发现，在整个美国大陆的广泛地点，地形符合泥沙通量定律，其中输运与地形梯度非线性成正比。(C) 2016年作者。地球表面过程和地形由约翰威利和儿子有限公司出版。
Hillslope length is a fundamental attribute of landscapes, intrinsically linked to drainage density, landslide hazard, biogeochemical cycling and hillslope sediment transport. Existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope-area scaling, where the hillslope domain transitions into the fluvial domain. Here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model (DEM), based on flow directions calculated using pixel aspect, until reaching the channel network, defined using recently developed channel extraction algorithms. Through comparisons between these measurement techniques, we show that estimating hillslope length from plots of topographic slope versus drainage area, or by inverting measures of drainage density, systematically underestimates hillslope length. In addition, hillslope lengths estimated by slope-area scaling breaks show large variations between catchments of similar morphology and area. We then use hillslope length-relief structure of landscapes to explore nature of sediment flux operating on a landscape. Distinct topographic forms are predicted for end-member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient. Because our method extracts hillslope profiles originating from every ridge-top pixel in a DEM, we show that the resulting population of hillslope length-relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes. We find that across a broad range of sites across the continental United States, topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient. (C) 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.