The availability and precision of topographic data determines the reliability of the calculated slope length and slope gradient (LS) factor, which limits the use of the universal soil loss equation (USLE) and its adapted versions in region-scale soil erosion risk assessment. One of the common complications is the effectiveness of topographic data with different resolutions or the compatibility of topographic data originated from different sources. In this study, the topographic data from five common sources, 5-m digital elevation model (DEM) based on 1:10,000 topographic maps (5-m topo DEM of 1:10,000), 25-m DEM derived from 1:50,000 topographic maps (25-m topo DEM of 1:50,000), 30-m ASTER GDEM, 30-m and 90-m SRTM DEMs, were individually applied to calculate the LS factors of five catchments with distinct terrain characteristics. Our results show that the computation accuracy of the LS factors in the five study catchments decreased with greater grid sizes derived from the five topographic data sources. Compared to the most precision 5-m topo DEM of 1:10,000, the relative computation error of the mean LS factors was less than 10% when calculated from the 25-m topo DEM of 1:50,000, and that was less than 25% from the 30-m ASTER and 30-m SRTM DEMs. For scenarios in gently rolling areas, the 90-m SRTM DEM with the relative computation error less than 15% could be recommended when there are noises on the open sources DEMs surface. Therefore, depending on the requirements of data accuracy, different data sources can be applied individually or in combined to obtain the optimal predictions of the LS factors. However, such recommendations on data sources proposed in this study appeared to be more applicable for regions with complex terrains. Further studies over a range of terrain features and spatial scales are required to validate the effectiveness of different topographic data sources in calculating the LS factor.

地形数据的可用性和精度决定了计算出的坡长和坡度（LS）因子的可靠性，这限制了通用土壤流失方程（USLE）及其改编版本在区域规模土壤侵蚀风险评估中的使用。常见的并发症之一是具有不同分辨率的地形数据的有效性或源自不同来源的地形数据的兼容性。在这项研究中，来自五个常见来源的地形数据：基于1：10,000地形图的5-m数字高程模型（DEM）（5-m地形DEM为1：10,000），25-m DEM来自于1：50,000地形分别应用了地图（25米topo DEM为1：50,000），30米ASTER GDEM，30米和90米SRTM DEM来计算LS五个具有不同地形特征的集水区的影响因子。我们的结果表明，随着来自五个地形数据源的更大网格大小，五个研究流域中LS因子的计算准确性下降。与最精确的1：m的5-m拓扑DEM相比，平均LS的相对计算误差从25米topo DEM（按1：50000计算）时，因子小于10％，而从30米ASTER和30米SRTM DEM中计算得出的因子小于25％。对于在平缓滚动区域中的场景，当开源DEM的表面有噪声时，建议使用相对误差小于15％的90米SRTM DEM。因此，根据数据准确性的要求，可以单独或组合使用不同的数据源以获得LS因子的最佳预测。但是，这项研究中提出的有关数据源的建议似乎更适用于地形复杂的地区。需要对一系列地形特征和空间尺度进行进一步研究，以验证不同地形数据源在计算地形时的有效性。LS因子。