WEPP模型坡面版在黄土丘陵沟壑区的适用性评价--以坡长因子为例

利用安塞试验站1985—1992年的气象观测数据和野外坡长径流小区径流量和土壤侵蚀量监测资料,评价了WEPP模型在黄土丘陵沟壑区不同坡长条件下的适用性。结果表明,在10,20,30和40m这4个坡长条件下,WEPP模型对次降雨、年平均和多年平均径流量的模拟结果略差;而WEPP模型对次降雨和年平均土壤侵蚀量模拟结果较好,无论是模拟值在不同坡长之间的差值,还是模拟值随坡长变化趋势均与实测值接近。WEPP模型对次降雨和年平均径流量模拟的Nash-Sutcliffe有效性ME分别为0.915和0.879;对次降雨和年平均土壤侵蚀量模拟的Nash-Sutcliffe有效性ME分别为0.853和0.758。WEPP对多年平均径流量和侵蚀量的模拟效果可满足要求。I30对WEPP模型模拟次降雨径流量有重要影响,当I30大于0.92mm/min,模型模拟误差较大。WEPP模型对次降雨土壤侵蚀量的模拟与PI30密切相关,当PI30大于129mm2/min时,模型模拟误差较大。∑PI30对WEPP模型模拟年平均径流量和侵蚀量有重要影响,当∑PI30大于150mm2/min时,模拟精度明显下降,且∑PI30对径流模拟的影响明显大于对土壤侵蚀模拟的影响。

Assessment of WEPP Model Applicability(Hillslope Version) on Hill-gully Region of the Loess Plateau--A Case Study in Slope Length Factor

Based on observed meteorological data and measured soil loss data from field runoff plots in 1985-1992 at Ansai Comprehensive Experimental Station, the applicability of WEPP model to different slope lengths on hil-lgully region of the Loess Plateau was assessed. Results showed that simulated values of event runoff, annual runoff, and average annual runoff by WEPP model were not desirable for the slope lengths of 10 m, 20 m, 30 m and 40 m. How ever, the simulated values of event soil loss and annual soil loss by WEPP model were desirable for the slope leng ths of 10m, 20m, 30 m and 40 m, respect ively. The differences of simulated values between slope lengths and increasing trend with increase of slope length were close to observed data of the soil loss. The Nash-Sutcliffe model ef ficiencies of event runoff simulat ion and annual runoff simulation were 0.915 and 0.879, respectively; and the Nash-Sutcliffe model efficiencies of event soil loss simulat ion and annual soil loss simulat ion were 0.853 and 0.758, respect ively. The simulated accuracy of annual average runoff and soil loss by WEPP model ws satisfied. I30 had a great effect on runoff simulated values at individual storms; the error between simulated values and observed data probably increased when I30 was hig her than 0.92mm/ min. The soil loss simulated values at individual storm had a close correlat ion with PI30, and the error betw een simulated values and observed values increased when PI30 was greater than 129mm2/ min.PI30was an important factor affect ing simulated accuracy of WEPP model, and simulated accuracy decreased when the PI30 was higher than 150mm 2/ min;meanw hile, the effect of PI30 on runoff simulation was more greater than that on soil loss.