基于DEM的坡长计算方法比较分析

坡长是重要的地形因子，流域坡长的提取有多种方法，国内应用到实际研究中的有基于格网的直接计算法和基于山脊线的快速计算法。以陕西省安塞县大南沟流域5m分辨率DEM为数据源探讨这两种方法的提取精度，分析可能存在的问题。在ArcGIS9．0环境中分别用直接计算法和快速计算法进行坡长提取，并与通过地形图量算的坡长进行比较分析。结果表明，直接方法计算结果的合格率为86．9％，与量算值之间的相关系数为0．800，确定性系数为0．520。快速计算法的合格率为69．7％，相关系数为0．276，确定性系数为-0．150，说明直接计算法的精度比快速计算法高。

A Comparison of Metheods for Computating Slope Length Based on DEM

Slope length is an important topographic factor. There are various methods to extract the slope length factor of a watershed. Both of grid based direct calculation method and fast calculation method based on the ridge line have been used in practical research in China. Based on the DEM data of the Danangou watershed in Shaanxi Province, this study attempts to make a comparison of precision for the two methods, and analyze the problems that may exist. Results show that direct calculation method has the eligible ratio of 86. 9% and model efficiency of 0. 520, whereas fast calculation method has the eligible ratio of 69. 7% and model efficiency of -0. 150. It can be seen that direct calculation method is superior to fast calculation method. This study can serve the further research work on slope length calculation and other related fields.