基于模拟降雨的土壤表土结皮特征及坡面侵蚀响应

Soil Surface Crust Characteristic and Response Feature to Slope Erosion Base on Simulation Rainfall

土壤表土结皮对坡面侵蚀过程具有重要影响,利用模拟降雨条件下土壤贯入和产流产沙试验,对不同降雨场次紫色土和黄壤表土结皮特征及坡面侵蚀响应进行研究。结果表明:(1)PT型贯入仪测定的贯入数值(P)与含水率(θ)成标准指数函数关系。(2)不同降雨场次表土结皮存在"无结皮→弱结皮→强结皮→弱结皮→新结皮"的动态发育过程,相同降雨条件下黄壤表土结皮强度大于紫色土的。(3)持续降雨过程不同降雨场次土壤表土结皮对溅蚀影响不明显,而与产流存在显著的动态响应关系,结皮强度越大产流量也越大,结皮对产流的影响随着降雨进行而有增大趋势,黄壤表土结皮的径流增加量大于紫色土的,而紫色土坡面结皮对产流量变化敏感程度大于黄壤。不同场次降雨过程土壤表土结皮对坡面侵蚀产沙影响存在差异,前4场降雨表土结皮强度与坡面侵蚀产沙有相同的变化趋势,4次降雨后土壤表土结皮表现为对坡面侵蚀有抑制作用。

Crust on the soil surface has an important influence on erosion process.Using the simulated rainfall and sediment penetration test method,the characteristics of soil crust development and erosion response in different rainfall with purplish soil and yellow soil were carried out.The results showed：（1） The relationship between penetration values（P） and moisture content（θ） measuring with PT-type penetrometer conformed a standard exponential function.（2） The soil surface crust in different rainfall existed the dynamic development process of ＂no crust → weak crust→ hard crust→ weak crust → new crust leather＂,and the surface of yellow soil crust intensity was more strength than purplish soil in same rainfall condition.（3） The soil surface crust was not significant influence to soil splash erosion in the continuous rainfall during the different storms,but there was a dynamic response between soil surface crust and runoff.The degree of influence to runoff by soil surface crust had increased with continuous experiment of simulated rainfall.The increment of the yellow soil point＇s overland runoff at the condition of soil crust was more than that of purplish soil point＇s,but the sensitivity to the runoff of purplish soil was higher than yellow soil.There were different impact relationships between soil surface crust and slope erosion.It had a same trend between soil surface crust strength and slope erosion at the former of four times rainfall,and soil surface crust showed the inhibitory to slope erosion after four rainfall experiments.