Modelling gully erosion for a small catchment on the Chinese Loess Plateau
Modelling gully erosion for a small catchment on the Chinese Loess Plateau
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DOI：
10.1016/s0341-8162(03)00061-4
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发表时间：
2003-11-30
期刊：
影响因子：
6.2
通讯作者：
van Asch, T
中科院分区：
文献类型：
--
作者：
Hessel, R;van Asch, T
中国黄土高原丘陵地带是地球上水土流失速率最高的地区之一。这个地区的一个显著特征是有许多大型的、永久性的沟壑。选择了一个3.5 km(2)的流域来研究侵蚀过程，并使基于风暴的林堡土壤侵蚀模型（LISEM）适应黄土高原的普遍条件。这项工作的一部分包括绘制和测量最大的沟壑。此外，还对切口下方的松散土壤进行了估算。观测结果表明，沟壑头部相对稳定（即，不会迅速迁移），但沟壑在陆地流事件中仍能产生大量沉积物。头部的侵蚀主要是由风暴之间的土壤落下造成的。这些土落产生的松散土壤物质在沟底堆积。由于LISEM模拟的是风暴侵蚀，沟槽随时间的发展可以忽略不计，只需要研究它们在径流事件中产生的物质量。数字高程模型（DEM）通过应用Montgomery和Dietrich [Science 255(1992) 826]指数的改编形式来估计现有沟头的位置。假设巷道是垂直的，就可以从坡角图中计算出巷道高度。采用了一个简单的稳定性模型，该模型假设土壤落在沟壑头部是土壤含水量和头部高度的函数。然后，这个基于日的模型可以用来模拟头部下方松散土壤物质的积累。结果表明，虽然DEM不够精确，无法检测到单个头部切口，但该方法可以用来对可用的松散土壤物质量进行合理估计。然后，显示松散土壤物质积累量的地图可以作为基于风暴的侵蚀模型（如LISEM）的输入。(C) 2003 Elsevier Science B.V.版权所有
The rolling hills region of the Chinese Loess Plateau is one of the areas with the highest erosion rates on earth. A striking feature of this area is the occurrence of many large, permanent gullies. A 3.5-km(2) catchment was selected to study the processes of erosion and to adapt the storm-based Limburg Soil Erosion Model (LISEM) to the conditions prevailing on the Loess Plateau. Part of this work consisted of mapping and measuring the largest gully headcuts. The amount of loose soil material beneath the headcuts was also estimated. Observations suggest that gully headcuts are relatively stable (i.e., do not migrate rapidly), but that gullies can nevertheless produce significant amounts of sediment during overland flow events. Erosion of headcuts occurs mainly by soil falls in between storms. The loose soil material produced by these soil falls accumulates on the gully bottom. As the LISEM simulates storm erosion, the development of gullies over time can be ignored, and only the amount of material produced by them during runoff events needs to be studied. A digital elevation model (DEM) was used to estimate the position of existing gully heads by applying an adapted form of the Montgomery and Dietrich [Science 255 (1992) 826] index. Using the assumption that headcuts are vertical, it is possible to calculate headcut height from, the slope angle map. A simple stability model, which assumes soil falls on gully headcuts to be a function of soil moisture content and headcut height, was applied. This daily-based model can then be used to simulate the accumulation of loose soil material below the headcut. The results show that while the DEM is not accurate enough to allow the detection of individual headcuts, this method can be used to produce a reasonable estimate of the amount of loose soil material available. A map showing the amount of loose soil material accumulated can then serve as input for a storm-based erosion model such as LISEM. (C) 2003 Elsevier Science B.V. All rights reserved.