Effects of DEM resolution on the accuracy of gully maps in loess hilly areas
Effects of DEM resolution on the accuracy of gully maps in loess hilly areas
复制标题
DEM分辨率对黄土丘陵沟壑地图精度的影响
DOI：
10.1016/j.catena.2019.02.010
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发表时间：
2019
期刊：
影响因子：
6.2
通讯作者：
Tang Guoan
中科院分区：
文献类型：
--
作者：
Dai Wen;Yang Xin;Na Jiaming;Li Jingwei;Brus Dick;Xiong Liyang;Tang Guoan
沟壑地图是研究沟壑侵蚀和土地退化的重要前提。人们提出了许多基于数字高程模型（DEM）的方法来实现自动沟渠测绘。然而，从 DEM 导出的沟壑地图的精度不可避免地受到 DEM 分辨率的影响。本研究调查了 DEM 分辨率对沟壑地图精度的影响。采用一系列分辨率为 0.1-10m 的 DEM 来绘制沟壑区域。 DEM 分辨率对绘制沟壑区域的误差和位置误差的影响通过回归模型来描述。中国黄土高原丘陵地区两个流域的结果如下。分辨率为 0.5-2m 的 DEM 最适合沟壑测绘。非常高分辨率的 DEM 会增加局部位置误差并过度预测沟壑的范围，而分辨率较低的 DEM 会导致绘制的沟壑边界向下迁移，从而导致沟壑区域的预测不足。然而，DEM 分辨率对沟壑地图的影响不是恒定的，而是随空间变化的。分辨率效应的空间差异与沟壑形态有关。 V型沟壑对沟壑地图的分辨率影响强于U型沟壑。本研究结果可用于选择合适的 DEM 分辨率用于黄土丘陵地区沟壑测绘，并有助于利用 DEM 来理解沟壑特征。
Gully maps are important prerequisites for the study of gully erosion and land degradation. Many digital elevation model (DEM)-based methods have been proposed to enable automated gully mapping. However, the accuracy of a gully map derived from a DEM is inevitably affected by the DEM resolution. This study investigates the effects of DEM resolution on the accuracy of gully maps. A series of DEMs with resolutions of 0.1–10 m is employed to map gully areas. The effects of DEM resolution on the error in the mapped gully area and on the position error are described by regression models. The results from two catchments in hilly areas of the Loess Plateau in China are as follows. DEMs with resolutions of 0.5–2 m are the most suitable for gully mapping. Very high-resolution DEMs increase local position errors and over-predict the extents of gullies, whereas DEMs with coarser resolutions cause the downward migration of mapped gully boundaries, resulting in the under-prediction of gully areas. However, the effects of DEM resolution on gully maps are not constant but vary in space. The spatial disparities of the resolution effects are related to the gully morphology. The resolution effects on the gully maps in V-shaped gullies are stronger than those in U-shaped gullies. The findings of this study can be used to select a suitable DEM resolution for gully mapping in loess hilly areas and contribute to understanding the characterization of gullies by using DEMs.