ALTERNATIVE APPROACHES FOR DETERMINING THE USLE-M SLOPE LENGTH FACTOR FOR GRID CELLS
- Peter I. A. Kinnell *
Erosion within a grid cell depends on cell size and the size of the area that is upslope of the cell. The factor accounting for slope length when the USLE-M is applied to predicting erosion in grid cells needs to (a) equal the universal soil loss equation (USLE) slope length factor for the cell when the area above the cell is completely pervious and (b) be directly related to the Desmet and Govers slope length factor when runoff is generated uniformly over the whole area. The procedure for calculating the slope length factor proposed previously fails to meet the second criteria. Alternative approaches which consider the contribution of the upslope area to the determination of the slope length factor to vary when the ratio of the runoff coefficient of the upslope area varies from that of the cell are described and shown to meet both criteria. The approach where the slope length factor is based on the ratio of the runoff coefficients for the upslope area and the upslope area plus the cell produces slope length factor values that lie within theoretically acceptable boundaries.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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