WEPP模型(坡面版)在贵州石漠化地区土壤侵蚀模拟的适用性评价

Assessment of the applicability of the WEPP model(Hillslope Version)for soil erosion in karst rock desertification area,Guizhou Province

文章以贵州花江喀斯特石漠化地区为研究区域,利用WEPP模型(坡面版)分别模拟2006年、2010年土壤侵蚀模数,并将实测数据与WEPP模型模拟值作比较,探讨WEPP软件在喀斯特石漠化地区的适用性。研究表明:WEPP模型对于模拟喀斯特石漠化地区土壤侵蚀有较大误差,对土壤侵蚀模数模拟的有效性系数均为负值,不适用于直接计算该区域土壤侵蚀模数。WEPP模型对微度侵蚀模拟精度不够,但能大体反映不同径流小区之间土壤侵蚀强弱的关系和生态修复过程土壤侵蚀的变化趋势。若要应用WEPP模型对喀斯特地区土壤侵蚀模数模拟计算,必须考虑水土的地下漏失、地表裸岩率、地形高度破碎等环境条件。裸岩率、土壤漏失、地形条件等都是WEPP模型修正所必须注意的内容。

The Huajiang demonstration area（total area = 47.63 km^2） in Guizhou Province was used as a study area to assess the applicability of the WEPP（Hillslope Version） model for soil erosion in karst rock desertification areas.The Huajiang demonstration area,which features typical-canyon in karst plateau,covers both sides of Huajiang river between Guanling county and Zhenfeng county in southwest Guizhou.The demonstration area is in the Panjiang syncline composed of Upper and Middle Triassic carbonates,with lime soil.The soil erosion area is 23,62 km^2,that is 49.6%of the total area,indicating that the soil erosion is serious.Using the runoff plot method and the erosion pin technique,the author monitored and simulated soil loss in the demonstration area in 2006 and 2010 using the WEPP model（Hillslope Version）.The applicability of the WEPP model to karst rock desertification areas was assessed by comparing monitoring and simulating data,and the Nash-Sutcliffe coefficient was calculated.The simulation results showed relatively large error and the effective coefficients were negative indicating that the WEPP model is not applicable for direct calculation of the soil erosion modulus in the karst areas of Guizhou.Although the simulation accuracy for soil erosion on micro scale is not sufficient,it generally reflects the different soil erosion intensities between different runoff plots and the relationship between the process of ecological restoration and the changing trend of soil erosion.The application of the WEPP model to soil erosion calculation in karst areas must take into account environmental factors such as underground leakage,rate of bedrock outcropping,and highly broken terrain.