WEPP细沟剥蚀率模型正确性的理论分析与实验验证

Theoretical analysis and experimental verification of the detachment rate equation of rill erosion in WEPP

基于物理过程基础上的WEPP土壤水蚀预报模型将坡面侵蚀分为细沟侵蚀和细沟间侵蚀,建立了独立的细沟间模型和细沟模型。其中细沟侵蚀产沙方程从概念上可以预报细沟侵蚀过程,但没经实验或理论验证。该文经过理论分析表明,WEPP模型中的剥蚀率是水流含沙量的线性函数,并由给定的试验条件计算得到了函数中的参数。将理论分析结果和已有的实验结果进行了比较,验证了WEPP中的侵蚀产沙模型。同时将已得到的确定细沟剥蚀率的微分方程代入细沟侵蚀产沙方程并求解,从理论上得到了含沙量随沟长变化的函数关系。将理论分析结果和由实验所得的结果进行了对比,进一步验证了WEPP中的侵蚀产沙模型。该文从细沟剥蚀率和产沙量两方面对WEPP模型中细沟侵蚀产沙模型进行了验证。

WEPP (Water Erosion Prediction Project), a physical-process-based soil erosion prediction model partitions the hillslope soil erosion into rill erosion and inter-rill erosion, with independent prediction models. The sediment source equation for soil detachment in WEPP is conceptually rational, but yet to be verified experimentally or theoretically. Theoretical analysis determines that the detachment rate equation in WEPP is indeed a linear function of the sediment concentration in runoff. The parameters for the detachment function under given experimental conditions were estimated and were compared with those parameters, directly determined from the experimental data, to validate the WEPP detachment equation. Integration of the differential equation for detachment rate was also used to derive the sediment concentration function of rill length. The estimated parameters of the sediment yield function were compared with those in the sediment-rill length function as determined from experimental data, to further validate the detachment rate model in WEPP. The detachment rate equation in WEPP was validated with both the detachment rate and the sediment yield.