模拟降雨条件下生物结皮坡面产流产沙对雨强的响应

生物结皮是黄土丘陵区退耕地广泛存在的地被物.本研究通过人工模拟降雨试验分析了雨强对生物结皮坡面产流产沙的影响.结果表明: 生物结皮坡面产流产沙随降雨历时的延长先增加、10~18 min趋于平稳.相对于裸土坡面,生物结皮显著延长了坡面初始产流时间,抑制了坡面产流产沙,可降低21%~78%的坡面径流量和77%~95%的产沙量.雨强主要通过影响生物结皮坡面径流而影响其产沙.随着雨强的增加,生物结皮坡面产流产沙与雨强的相关性出现了由不显著相关向显著相关的转折,雨强＞1.5 mm·min^-1时,生物结皮坡面的减流减沙作用随着雨强的增加而降低.本研究结果为降雨条件下生物结皮坡面产流产沙过程的模型模拟奠定了基础.

Responses of runoff and soil loss from biological soil crustal slope to rainfall intensity under simulated rainfall.

Biological soil crust (biocrust) is a common surface cover on the rehabilitated slope land in Hill Loess Plateau. We investigated the responses of runoff and soil loss from biological soil crustal slope to rainfall intensity by using simulated rainfall trial. The results showed that the runoff and soil loss from biocrust slopes increased sharply at the beginning stage of rainfall and then became stable during 10 to 18 min. Compared to bare soil slope, the initial runoff generation time of biological soil crustal slope was significantly increased. The presence of biocrust could significantly decrease runoff and sediment by 21%-78% and 77%-95%, respectively. Rainfall intensities affected soil erosion of biocrust slopes mainly via affecting runoff. The transition from insignificant to significant correlation between runoff and soil loss from biological soil crustal slopes and rainfall intensities was observed with the increases of rainfall intensities. Once the rainfall intensity was higher than 1.5 mm·min^-1, there was a significant decrease in the function of biocrust to decrease runoff and soil loss with the increases of rainfall intensities. Our results laid the foundation for the model simulation of runoff and soil loss from biocrust slopes under rainfall conditions.