侵蚀程度差异诱发的坡面产流-产沙-总磷流失特征

The characteristics of runoff-sediment yield and total phosphorus loss induced by the soils of different erosion degree

为了研究不同侵蚀程度下土壤坡面产流产沙及携磷流失特征,以浙江省湖州市安吉县风化花岗岩母质上发育的坡地土壤为研究对象,选择侵蚀强度不同的出露土层(分别为砂土层(A组)和红土层(B组))两组土壤进行人工模拟降雨试验.结果表明:坡地磷素流失主要以侵蚀泥沙为主,径流携磷流失中以地表径流携带流失为主,壤中流磷素流失量较小;由于土壤机械组成、容重的差异,B组土壤壤中流流量及其携磷流失量远小于A组土壤壤中流流量及其携磷流失量;雨强对坡面径流中磷素流失浓度的影响明显,坡面径流和壤中流磷素流失浓度相差极大;两组土壤坡面径流量受雨强的影响基本一致,均为150 mm·h^(-1)>120 mm·h^(-1)> 90 mm·h^(-1)> 60 mm·h^(-1)>30 mm·h^(-1),不同的是红土层土壤坡面径流产流量较大且变幅小;随雨强增加两组土壤壤中流变化特征差异明显,红土层土壤在不同雨强下的壤中流流量排序为90 mm·h^(-1)>120 mm·h^(-1)> 60 mm·h^(-1)> 30 mm·h^(-1)>150 mm·h^(-1),砂土层土壤在不同雨强下的壤中流流量排序为150 mm·h^(-1)>120 mm·h^(-1)> 90 mm·h^(-1)> 60 mm·h^(-1)>30 mm·h^(-1);侵蚀泥沙富集较小颗粒(粉粒、粘粒)和磷素,其磷含量均高于试验用土磷含量;雨强越大,土壤细颗粒含量越高,侵蚀泥沙产量越大.

In order to study the characteristics of runoff, sediment yield and phosphorus loss on slope, the artificially simulated rainfall experiment was respectively carried out on two groups of soil, which developed from sandy soil layer(group A) and red soil layer(group B) of weathered granite in Zhejiang Province. The slope was set at 25° and the rainfall intensity were respectively set at 30, 60, 90, 120 and 150 mm·h^-1. Totally there are 10 effective rainfall with two groups of soil. Main conclusions were as follows:①Phosphorus loss was mainly caused by slope runoff. The phosphorus loss through interflow was extremely small relative to slope runoff. But considering the persistence of interflow, it poses a certain threat to water environment.②Due to the difference in soil mechanical composition and bulk density, the volume and the total phosphorus loss of interflow in group B were much smaller than those in group A.③The effect of rainfall intensity on total phosphorus concentration of slope runoff was obvious, and the total phosphorus concentration in slope runoff and interflow varied significantly.④The volume of slope runoff in two groups was all basically affected by rainfalll intensity. The difference is that the initial slope runoff volume of group B was large.⑤Different with the slope runoff, the effects of rainfall intensity on the interflow for two groups was obvious. With different rainfall intensity, the volume of interflow in group A followed by 150 mm·h^-1>120 mm·h^-1>90 mm·h^-1>60 mm·h^-1> 30 mm·h^-1. However, the rank for another group was 90 mm·h^-1>120 mm·h^-1>60 mm·h^-1>30 mm·h^-1>150 mm·h^-1, which related to hydraulic characteristics of soils caused by different bulk density and mechanical composition. In essence, it is related to the erosion degree.⑥With the increasing of rainfall intensity and soil fine particles, the yield of erosive sediment increased. And erosion sediment enriched with smaller particles(clay and silk particles) and phosphrous, which is consistent with most previous research results.