Slope length factor for applying the USLE-M to erosion in grid cells

Often, the modelling of the spatial variation in erosion in catchments involves using the universal soil loss equation (USLE) to predict erosion in grid cells. However, the impact of variations of runoff from upslope caused by factors other than space is ignored if slope length is determined from nothing more than the drainage area as is the current practice when the USLE is applied to grid cells. The USLE-M, a version of the USLE based on event erosivity being described by the product of the runoff ratio and the EI30 index, requires the use of a slope length factor that is hydrologically based.