基于WEPP的黄土丘陵区不同坡长条件下坡面土壤侵蚀预测

为了更全面地评价WEPP模型在我国的适用性，该文通过建立模型数据库，利用WEPP分别模拟了坡长为10、20、30和40 m的径流量和土壤侵蚀量，并用实测径流和侵蚀资料进行对比分析。结果表明，在10、20、30和40 m 4个坡长条件下，WEPP模型对降雨、每年和多年平均径流量模拟的Nash-Sutcliffe有效性(ME)分别为0.915、0.879和-0.056，对单场降雨、每年和多年平均土壤侵蚀量模拟的ME分别为0.853、0.758和-0.456，多年平均的ME为负值可能是由小样本计算造成的。WEPP模型对单场降雨和每年径流量和侵蚀量模拟效果较好。尽管WEPP模型对多年平均径流量和土壤侵蚀量模拟效果较差，但模型模拟的多年径流量和土壤侵蚀量与实测值的多年径流量和土壤侵蚀量的最大相对误差分别为7.90%和29.20%，表明WEPP模型对多年径流量和侵蚀量的模拟可满足要求。径流量模拟值随坡长增加的变化和实测值相比不够敏感；而土壤侵蚀量模拟值随坡长增加的变化和实测值相比过于敏感。 

Hillslope soil erosion prediction based on WEPP model under different slope lengths in hilly-gully region of the loess area

The water erosion prediction project(WEPP) model is a new generation water erosion prediction model,and is capable of providing scientific guidance to soil erosion intensity assessment and land resources management.Since the development of WEPP model,many countries have tried and tested the applicability of it.Though several studies were conducted in China to evaluate the model, there was little work done for assessing WEPP model application under different slope lengths.In order to assess the applicability of WEPP model in China,the authors compiled a WEPP model database,simulated runoff and soil loss for slope lengths of 10, 20,30 and 40 m,and compared the simulated runoff and soil loss and those of measured values.The results showed that the Nash-Sutcliffe model efficiency(ME) of even runoff simulation,annual runoff simulation and average annual runoff simulation were 0.915,0.879 and-0.056,respectively;and the Nash-Sutcliffe ME of the corresponding soil loss simulations were 0.853,0.758 and-0.456.The negative ME for average annual values was similar due to the small sample size used in its computation.The results showed that the WEPP model simulated eventual and annual runoff and soil loss well.Although the simulated accuracy for average annual runoff and soil loss simulation might be relatively low in this study,the maximum relative errors were 7.90% and 29.20% respectively, indicating that the WEPP model can predict average annual runoff and soil loss satisfactorily.Comparing with the measured data,the simulated runoff is less sensitive to the changes in slope lengths,but the simulated soil loss is more sensitive to slope length factor.