降雨条件下灌草配置方式对褐土坡面径流泥沙特征的影响

Effects of Different Configuration Patterns of Shrub and Grass on Runoff and Sediment Characteristics from Cinnamon Soil Under Rainfall Conditions

为探究不同灌草配置方式对褐土坡面土壤侵蚀的影响,通过室内模拟降雨试验,以种植灌木胡枝子(Lespedeza bicolor Turcz.)以及草本紫花苜蓿(Medicago sativa L.)的褐土坡面为研究对象,设计3种降雨强度(30,60,90 mm/h)、3种灌草覆盖度(灌草覆盖度比例分别为1∶2(Ⅰ),2∶1(Ⅱ),1∶1(Ⅲ))以及3种灌草空间配置方式(灌木位于坡上(US)、坡中(MS)、坡下(LS)),分析降雨条件下不同灌草覆盖度及不同灌草空间配置交互作用下产流产沙及减流减沙特征。结果表明:(1)坡面产流产沙量在降雨初期大幅度增加,随后增加趋势逐渐减缓,最后趋于稳定。当灌丛位于坡下(LS)且灌草覆盖度为Ⅱ时,产流产沙量显著低于其他灌草配置方式。(2)不同灌草覆盖度减流减沙率大小关系为Ⅱ>Ⅰ>Ⅲ;不同灌草空间配置下减流减沙率大小关系为LS>MS>US。其中最大减流率达61.58%,最大减沙率达93.27%。不同灌草配置方式间的减流率及减沙率具有显著差异。(3)通过双因素方差分析研究灌草空间配置方式对坡面总产流产沙量的显著性和贡献率发现,灌草覆盖度和灌草空间配置对总产流量和总产沙量均有显著性影响(p<0.05),但是灌草覆盖度和灌草空间配置交互作用对坡面总产流量和总产沙量影响并不显著。(4)灌丛于坡下、灌丛覆盖度为50%、草本覆盖度为25%的灌草配置方式有最好的减流减沙率,能最好地削减径流泥沙。研究结果可为北京褐土地区水土保持措施布设提供支撑。

In order to explore the effects of different configuration patterns of shrub and grass on soil erosion from cinnamon soil,a simulation rainfall experiments was conducted on cinnamon soil slopes planted with shrub(Lespedeza bicolor Turcz.)and the herbs(Medicago sativa L.).Three kinds of rainfall intensity(30,60,90 mm/h),three kinds of vegetation coverage(ratio of shrubs and herbs coverage was 1∶2(Ⅰ),2∶1(Ⅱ),1∶1(Ⅲ))and three kinds of vegetation patterns(shrubs were located on up-slope(US),middle-slope(MS),low-slope(LS))were designed to analysis the characters of runoff generation and sediment yield and the benefit of runoff and sediment reduction with the interaction between the vegetation coverage and vegetation patterns under rainfall conditions.The results showed that:(1)Runoff generation and sediment yield on slope increased greatly at the beginning of rainfall,and then the trend of increase gradually slowed down,and finally stabilized.When the shrubs were located at the low slope(LS)and the vegetation coverage wasⅡ,the runoff generation and sediment yield were the least.(2)The relationship of the effect of runoff reduction and sediment reduction between different vegetation coverage wasⅡ>Ⅰ>Ⅲ.The relationship of the effect of runoff reduction and sediment reduction between different vegetation patterns was LS>MS>US.(3)A double factor variance analysis showed that vegetation coverage and vegetation patterns exhibited a significant effect on runoff generation and sediment yield(p<0.05),but the interaction between the vegetation coverage and vegetation patterns became insignificant on runoff generation and sediment yield.(4)When the shrubs at the low slope with 50%shrub cover and 25%herbs cover,this configuration pattern had the best runoff and sediment reduction efficiency.The results of the study could provide support for the deployment of soil and water conservation measures in cinnamon soil area of Beijing.