Scale effects of DEM on erosion potentials in the western Chinese Loess Plateau

Although the geological factor and extensive human adverse impacts have exacerbated the soil erosion problems, the topography with accomplice of the above-mentioned hydrological characteristics controls the erosion potentials in the undulating hilly topography of the western part of the Chinese Loess Plateau. Thus, to estimate the spatial distribution of the topography-controlled erosion potentials, the spatial distribution of topographic attributes have to be spatially depicted. This paper apply the USPED model to four different scale DEMs in Gaoquangou watershed located in the western Chinese Loess Plateau to calculate the erosion potentials and evaluate the DEM scale effects on GIS-processes topographic parameters that are required in modeling the erosion potentials. Four differently-scaled DEM data (1:250,000, 1:50,000, 1:10,000, and 1:5,000) are re-sampled to 10-m resolution and the topographic parameters (e.g., slope, aspect, upslope contributing area, rill density and others) are GIS-processed to be input parameters in erosion model. The two most important erosion type, rill erosion and sheet erosion, are calculated from the four differently-scaled DEMs and the calculated results are compared and evaluated in terms of their theoretical and practical adequacy. The results show that the USPED model can be used to reasonably depict the effects of complex terrains on soil erosion. The comparison of calculated erosions from four scale DEMs indicates that 1:50,000 DEM can provide nearly equally accurate topographic information as higher-resolution DEM data for soil erosion studies, and 1:250,000 scale DEM underestimates the potential of rill erosion and sheet erosion