雨强和植被覆盖度对红壤坡面产流产沙的影响

为探究雨强和植被覆盖度对花岗岩红壤坡面产流产沙的影响,通过室内人工模拟降雨试验,分析了不同雨强(0.5,1.0,1.5 mm/min)和植被覆盖度(0,20%,40%,60%)下坡面侵蚀的产流、产沙规律及相关关系。结果表明:(1)同一雨强下,初始产流时间随植被覆盖度增加而延迟,并随雨强增大而提前,雨强越大,产流时间提前越明显;(2)各坡面径流率、侵蚀率随植被覆盖度增加而减小,且植被覆盖度越高,径流率和侵蚀率波动范围越小,侵蚀过程越稳定;(3)有植被覆盖的坡面,产沙主要以0.25 mm的水稳性团聚体为主,侵蚀泥沙中0.25 mm水稳性团聚体比重随雨强增大而增加,且增加的幅度随覆盖度的提高而减小;(4)雨强、植被覆盖度均与产流时间、径流率、侵蚀率呈现极显著相关关系(P0.01),且坡面产流过程与雨强变化的相关性大于其与植被覆盖度变化的相关性,坡面产沙过程与植被覆盖度变化的相关性大于其与雨强变化的相关性,不同雨强下植被覆盖坡面累积径流量和累积产沙量关系符合幂函数模型(R~20.98)。研究结果可为南方红壤丘陵区水土流失治理与生态恢复提供科学参考。

Effects of Rainfall Intensity and Vegetation Coverage on Runoff and Sediment Yield on Red Soil Slope

In order to investigate the effects of rainfall intensity and vegetation coverage on the runoff and sediment yield on granite red soil slope, this study analyzed regularity of runoff and sediment yield and their correlation under different rainfall intensities (0.5, 1.0, 1.5 mm/min) and vegetation coverages (0, 20%, 40%, 60%) through indoor artificial simulated rainfall test. The results showed that:(1) Under the same rainfall intensity, the initial flow time was delayed with the increasing of vegetation coverage, and it was advanced with the increasing of rainfall intensity. The greater the rainfall intensity, the earlier the flow time was. (2) The runoff rate and erosion rate of each slope decreased with the increasing of vegetation coverage, and the higher the vegetation coverage was, the smaller the fluctuation range of runoff rate and erosion rate was, and the more stable the erosion process was. (3) On the slope covered by vegetation, the sediment was mainly water-stable aggregates less than 0.25 mm. The proportion of water-stable aggregates greater than 0.25 mm in the sediment increased with the increasing of rainfall intensity, and the increase range decreased with the increasing of vegetation coverage. (4) Vegetation coverage and rainfall intensity were significantly correlated with runoff generation time, runoff rate and erosion rate (P<0.01). The correlation between slope runoff generation process and rainfall intensity was greater than that between slope runoff generation process and vegetation cover change. The correlation between slope sediment yield and vegetation cover change was greater than that between slope sediment yield and rain intensity change. The relationship between cumulative runoff and cumulative sediment yield on vegetation covered slope was in consistent with power function model(R²>0.98)under different rainfall intensities. The results could provide a scientific reference for soil erosion control and ecological restoration in red soil hilly area of southern China.