流径算法是分布式水文模型、土壤侵蚀模拟等研究中的关键技术环节,决定着汇水面积、地形指数等许多重要的地形、水文参数的计算。本文以黄土高原两个典型样区的不同分辨率DEM为研究对象,对常用的五种流径算法(D8、Rho8、Dinf、MFD和DEMON)通过相对差系数、累积频率图、XY散点分布图等进行了定量的对比分析。结果表明:算法的差异主要集中在坡面区域,汇流区域各类算法的差别较小;算法差异在不同DEM尺度下都有所体现,但高分辨率下的差异会更明显;在地形复杂区域,多流向算法要优于单流向算法。研究也进一步指出汇水面积、地形指数等水文参数对流径算法具有强烈的依赖性。

Flow routing algorithm, which is often used to calculate the terrain parameters such as catchment area, specific catchment area, topographic wetness index and so on, is a key point in distributed hydrologic models, soil erosion modeling and other geoscience fields. The results obtained by the flow routing algorithms have distinct effects on hydrological and soil erosion modeling process. So evaluating flow routing algorithms has become a focus in these fields. In this paper, five flow routing algorithms, which are known as D8 (Deterministic eight-node), Rho8(Random eight-node ), Dinf(D-infinite), MFD ( Multiple flow direction algorithm), and DEMON ( Digital Elevation Model Networks), are selected to compare and analyze quantitatively on two Digital Elevation Model (DEM ) with 5m, 10m and 25m horizontal resolution respectively. Coefficient of relative difference, cumulative frequency distributions and XY scatter plot of the Total Catchment Area (TCA) are designed to evaluate the similarities within the selected flow path algorithms. Also the effect of DEM resolution on TCA, obtained from the selected five algorithms, is fully discussed. The results of the paper are summarized as follows: 1) differences between catchment area values estimated by the selected five flow routing algorithms were the greatest along side slopes area, and the differences decreased where the terrain became more convergent or along the channel; 2) the difference exists in any DEM with various resolutions, but is more sensitive to the high resolution DEM; and 3) multiple flow direction (MFD) algorithm is more suitable to estimate catchment area in complex terrain area than single flow direction (SFD) algorithm does that. So if the condition permits or accurate results are needed, high resolution DEM and fine MFD should be used effectively. This study also points out that the choice of flow routing algorithm has potentially important consequences for the calculation of upslope contributing areas, sediment transport capacity, topographic wetness, and several other topographic indices.