坡度截断对分布式土壤侵蚀学坡长提取的影响

地形是影响土壤侵蚀的重要因子, 分布式土壤侵蚀学坡长是地形因子的重要参数。坡长与土壤侵蚀过程相适应, 在一定条件下停止累计而截断。坡度变化是坡长提取的截断条件之一, 但坡度变化对提取结果的影响研究还不够深入。以数学曲面和黄土高原县南沟流域的数字高程模型作为数据源, 使用LS_TOOL方法提取坡长, 并对坡度变化引起的坡长截断结果进行对比和主成分分析。结果表明, 下坡坡度减小幅度越大, 坡度截断效果越明显; 坡度小于2.86°的截断参数R₁和坡度大于或等于2.86°的截断参数R₂与坡长最大值和坡长平均值均正相关; 在黄土高原地区, 陡坡、沟道较多, 相对R₂的影响, R₁对坡长的影响较小。坡度变化的截断设置在R₁>0.7, R₂>0.5时, 坡长变化较明显, 建议黄土高原地区侵蚀坡长的坡度截断设置值为R₁=0.7, R₂=0.5。

Effect of Slope Cutoff in Extraction of Distributed Soil Erosion Slope Length

Topography is an important factor affecting soil erosion.Distributed soil erosion slope length is an important parameter of topographic factor.The slope length agree with the process of soil erosion, is calculated with the cutoff considered.Slope length, influenced by the terrain, especially the slope changes affects the extraction results are in urgent need of research.In this paper, the mathematical surface and the digital elevation model of the Xiannangou catchment in the Loess Plateau are used as the data source.The length of the slope is extracted by using the LS_TOOL method, and the slope length cutoff results caused by the change in slope are compared and analyzed by principal component analysis.The results show that the greater the down slop decrease, the more obvious the slope cutoff effect.The cutoff factor R₁ and cutoff factor R₂ have positively correlated with the maximum slope length and averages slope length; as there are more steep slopes and channels in the Loess Plateau region, the influence of R₁ is less than that of R₂.When the slope setting of the slope is larger than that of R₁> 0.7 and R₂> 0.5, the change of slope length is obvious.It is suggested that the slope cutoff setting of the slope length of the Loess Plateau region should be R₁=0.7 and R₂=0.5.