Study on the Distributed Slope Length for Soil Erosion Prediction at Watershed Scale

TitleStudy on the Distributed Slope Length for Soil Erosion Prediction at Watershed Scale
Publication TypeConference Paper
Year of Publication2013
AuthorsYang, Qinke, Hongming Zhang, Chunmei Wang, Mudan Zhao, Yongmei Liu, and Lei Wang
Refereed DesignationRefereed
Conference NameGeomorphometry 2013
Date Published2013
Conference LocationNanjing, China
AbstractAs the most mature and practical soil erosion prediction models so far in the world, USLE and its derivative models, including RUSLE and CSLE, have been widely applied in the soil erosion inventory and mapping at watershed and regional scale. In the models the impacts of terrain on soil erosion is represented by Length Slope factor (LS), which calculate based on DEM derived slope degree and slope length layers. The extraction of slope and slope length themes,especially the latter, of a watershed for each location is difficulty and key issue in the application of USLE to soil erosion assessment and mapping at watershed and regional scale. The issues reviewed and discussed in this paper include; (1) slope length (USLE slope length), at the slope scale, for soil erosion prediction is a specified term introduced by USLE to represent the influence of slope length to sheet and rill erosion, so the slope length is different from similar concepts in geomorphology and hydrology which is really a flow length in hydrology. (2) Slope length of the distributed basin soil erosion (watershed slope length, in short, WSL) refers to the slope length of erosion of any point within the basin that is consistent with the process of erosion, transportation and settlement of the slope soil within the basin when actual topographical conditions of the basin are taken into consideration; (3) The WSL is an extension of USLE slope length from hill slope to a compound terrain parameter in 3-D dimensional landscape, and orient to the USLE application directly in soil erosion survey and mapping. (4) There are 4 algorithms proposed by researchers, and there are more or lees differences between them, of which the cumulative runoff algorithm by Hickey and Van Remortel is much better than others. (5) the extraction of WSL is mainly influenced by four factors, including DEM resolution, flow direction algorithm, partitioning strategy of DEM datasets, and cut-off methods of slope length; (6) The issues should be further studied include principles and software tools for WSL extraction, variance structures and statistical distribution, uncertainties and applicability analysis of the WSL in the soil erosion study at watershed and regional scale.
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