坡面版WEPP模型在川中丘陵区的应用研究

Using Study of Sloping WEPP Model in Sichuan Hilly Basin

利用WEPP模型对川中丘陵区盐亭站5个径流小区土壤侵蚀量的预测和土壤侵蚀空间分布的模拟发现:WEPP模型对次降雨土壤侵蚀的预测,相对误差在30%以内的占总样本86%以上;对年降雨土壤侵蚀预测的误差较稳定,且相对误差均在15%以内。说明WEPP模型对长时间尺度的土壤侵蚀预测更准确。WEPP模型对土壤侵蚀空间分布的预测,通过坡面侵蚀曲线可以明显分出侵蚀发育区、加速侵蚀区和主要侵蚀区;降雨量和平均雨强越大,加速侵蚀区越短,侵蚀量越大;坡长越长,加速侵蚀区越长,侵蚀量越大,最大侵蚀量也越大。

This paper applies the WEPP model to simulate soil erosion and spatial variation in Sichuan hilly basin. The study was carried out on six cultivated slope lands and fifteen bare slope lands. As to single storm, the average relative error of six cultivated slope lands is 25.5%. The relative errors less than 30% account for 88.9% of all the errors of those six cultivated slope lands. The average error of fifteen hare slope lands is 20.3 %, the relative errors less than 30% account for 86% of all the errors of those fifteen bare slope lands. The relative errors of annual soil erosion in 2004 and 2005 are 14.94% and 14. 37%, respectively, which is less than those of single storms. So the WEPP model is more suitable to simulate soil erosion in long time scale. The WEPP model is also able to simulate the spatial variation of soil erosion. By means of sloping erosion curve, the erosion area can be divided into three parts： erosion developing part, erosion accelerating part and main erosion part. The length of erosion accelerating part has negative relation with rainfall and rainfall intensity, while the length of accelerating part and the erosion has positive relation with the length of slope.