流域分布式坡长不确定性的初步分析

地形因子坡长对水土保持和土壤侵蚀有着重要的影响作用,其不确定性又制约着坡长的应用,因此坡长不确定性的研究尤为重要。以水文地貌关系正确DEM(Hc—DEM)为基础,利用LS_Tool软件计算坡长,主要从流向算法、分辨率和数据范围影响三个方面对提取的坡长不确定性进行比较分析。结果表明,不同流向算法提取的坡长结果不同,多流向算法提取的坡长更光滑、连续,更能体现地形凹凸的影响;随着分辨率的降低,坡长会发生扩张现象,使地形变得平滑;坡长的计算应以流域边界或者行政单元边界向外缓冲一定宽度为界(本实验结果为120m缓冲区),以避免边际效应的产生。

Analysis on Uncertainty of DEM Derived Watershed Distributed Slope Length

Topographic factors of slope length on soil conservation and soil erosion has an important influence,and the uncertainty also restricts the application of the watershed distribution of slope length,the research about the uncertainty of the watershed distributed slope length has important significance.Uncertainty of the watershed distributed slope length derived from flow algorithm,DEM resolution and data extent was analyzed in this paper using LS_Tool software.It showed that different flow algorithms lead to different results,and the slope length extracted by multiple flow direction algorithms is smoother,more continuous,and better represents the terrain structure;the slope length increases as the resolution becomes coarser and more smooth;the calculation of slope length should be buffered in some distance for watersheds(120 m buffer in this test) or administrative boundary to avoid edge effects.