Analysis on erosional terrain characteristics of typical samples in main water erosion region of China

Abstract: Terrain is one of the main environmental factors that influence ground water and soil erosion. Slope gradient, Slope length, and LS factor are important in soil erosion models. In this paper, DEM with a resolution of 25m was built in the software ANUDEM and slope, slope length, and LS factor were calculated with support from the fourth national soil erosion survey. Spatial and statistical characteristics for terrain factors that influence soil erosion were analyzed, and the result was contrasted with two kinds of remote sensing based elevation data that were used widely. The result showed that the typical terrain characters could be expressed by Hc-DEM with a resolution of 25m. Slope gradient and a slope length based on 25m Hc-DEM in accordance with the conventional understanding. Slope gradient was gentlest in the northeast region and steepest in the Loess Hilly region. Slope length was longest in the northeast region and shortest in the Loess Hilly region. Slope gradient was gentle in the bottom of valleys and ridge areas with higher elevation, and was steep in areas between the ridge and deposition areas. In areas with great relief steep hilly areas or gentle hilly areas, slope length was longer. The spatial distributions of LS factor were similar with that of the slope gradient. The data of this research was proven to be better than ASTER and SRTM elevation data. Moreover, the DEM data built in the fourth national soil erosion survey was irreplaceable in the field of soil erosion mapping at the national, province, and large watershed scales. This paper showed the characteristics of erosional terrain in the main water erosion region in China, and the result provided a basis for the calculation of terrain factors in research of soil erosion and hydrology.