基于WEPP的砒砂岩坡面复合侵蚀治理生态水文效应评价

Evaluation of Eco-hydrological Effect of Composite Erosion Control of Pisha Sandstone Slope Based on WEPP Model

基于2014—2016年二老虎沟小流域坡面径流小区的7场野外降雨下径流泥沙监测数据,在砒砂岩区表土(0—20cm)条件下,通过累积误差法率定模型土壤参数;同时采用模型有效性系数(ME)和决定系数(R2)对模型有效性进行验证,并利用WEPP模型对不同侵蚀治理措施坡面径流泥沙情况进行了模拟预测,对其减流减沙生态水文效应进行了比较分析。结果表明:(1)当模型有效水力传导系数为4.73mm/h、临界剪切力为1Pa和细沟土壤可蚀性为0.01s/m时,模型模拟效果最佳。(2)WEPP模型模拟无措施(裸地)小区径流量和侵蚀量的R2分别为0.7223和0.7025,ME分别为0.6160和0.6167,WEPP模型模拟措施(草地)小区径流量和侵蚀量的R2分别为0.7116和0.8447,ME分别为0.6741和0.6903;措施小区的模型效果比无措施小区的模拟效果好。(3)不同降雨类型下,情景a(阳坡低盖度草本)、情景b(阳坡低盖度灌丛)、情景c(阳坡中盖度灌丛)、情景d(阴坡灌木林)、情景e(阴坡高盖度灌丛)、情景f(阴坡低盖度灌丛)的植物措施减流效应为13.04%~91.28%,减沙效应为44.46%~99.98%。总体来看,不同情景的减流减沙效应为情景d>情景e>情景c>情景f>情景b>情景a。

Based on the field monitoring data of runoff plot in erhugou small watershed from 2014 to 2016,under the condition of the surface soil(0—20 cm)in the pisha sandstone area,the soil parameters of the model were calibrated by the cumulative error method;at the same time,the model validity coefficient(ME)and the decision coefficient(R^2)were used to verify the model validity,and WEPP model was used to simulate the runoff and sediment conditions of different erosion control measures.The ecohydrological effects of runoff and sediment reduction were compared and analyzed.The results showed that:(1)When the effective hydraulic conductivity,critical shear force,and erodibility of rill soil are 4.73 mm/h,1 Pa and 0.01 m/s respectively,the simulation effect of the model is the best.(2)The R^2 and ME of WEPP model to simulate runoff and erosion of no measure(bare land)plot were 0.7223 and 0.6160,0.7025 and 0.6167 respectively,and the runoff and erosion of WEPP model to simulate measure(grassland)plot were were 0.7116 and 0.6741,0.8447 and 0.6903,respectively,and the simulation effect of the model with measures was better than that without measures.(3)Under different rainfall types,the effects of scenario a(herbage with low coverage on sunny slope),scenario b(shrub with low coverage on sunny slope),scenario c(shrub with medium coverage on sunny slope),scenario d(shrub with high coverage on cloudy slope),scenario e(shrub with high coverage on cloudy slope),and scenario f(shrub with low coverage on cloudy slope)on runoff reduction were 13.04%~91.28%,and the effects of sediment reduction were 44.46%~99.98%.In general,the effects of different scenarios were:scenario d>scenario e>scenario c>scenario f>scenario b>scenario a.