Development of a Soil Erosion Classification System for Cut and Fill Slopes

摘要

The Universal Soil Loss Equation (USLE) has been widely used to predict the long-term average annual soil loss associated with sheet and rill erosion caused by rainfall and runoff. Initially developed for agricultural purposes, it was later modified and extended for estimating soil loss on cut and fill slopes. In addition to this valuable equation, management of cut and fill slopes also requires a classification system in order to prioritize erosion control measures and maintenance operations based on estimated soil loss. Currently available erosion classifications (focused on soil productivity and sustainable agriculture) may not be relevant to transportation infrastructure slopes, in which soil loss rates are dramatically higher and primarily concern operational service conditions. Therefore, the objective of this study was to develop a classification system based on soil loss rates computed by the USLE model that can be valuable for management of cut and fill slopes. It was assumed that erosion classifications developed for agriculture could be used in cut and fill slopes as long as the ratio between respective soil loss rates was applied. It was found that the topographic factor, which accounts for the length and steepness of the slope, may explain most of the difference in respective soil loss rates. For typical values of the topographic factor, soil loss rates on cut and fill slopes were found to be roughly ten times greater than those on agriculture. Based on this finding, a new classification with six erosion levels was developed. Finally, validation analysis showed that the proposed classification successfully ranked soil loss rates reported in the literature into different categories.