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Theoretical Analysis and Experimental Verification of Soil Detachment Rate Equation of Rill Erosion in WEPP

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  032362,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14039) @2003
Authors:   Lei, Tingwu, Qingwen Zhang, Pan Yinghua, Wang Hui
Keywords:   Water Erosion Prediction Project, Rill erosion, Soil detachment rate, Verification

Rill erosion research and its prediction are of great importance. The physical-processbased soil erosion prediction models such as WEPP (Water Erosion Prediction Project) were developed for these purposes. The sediment source equation for soil detachment in WEPP is conceptually rational, but yet to be verified experimentally or theoretically. This study, with theoretical reasoning and experimental proof was conducted to validate the detachment rate model adopted in WEPP. Theoretical analysis determines that the detachment rate equation is indeed a linear function of sediment concentration in runoff, which was verified with laboratory experiments. Methods for estimating these parameters of the linear function were outlined. And the parameters for this function under given experimental conditions were estimated accordingly and were compared with those parameters in the similar functional relation, directly determined from the experimental data. Comparison of these parameters estimated with the above mentioned two different ways was made to validate the WEPP detachment equation. The differential equation for detachment rate was also used to derive the sediment concentration function of rill length. The method for estimating the parameters from those in the detachment model was advanced and the parameters in the function were estimated from the parameters of the above detachment rate model. These estimated parameters were compared with those in the sediment-rill length function as determined from experimental data. The detachment rate model in WEPP was further validated. And the conditions under which the soil detachment equation is applicable were discussed.

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