模拟降雨条件下秸秆覆盖对崩积体侵蚀产流产沙的影响

Effect of Straw Mulch on Colluvial Soil Erosion and Yield of Runoff and Sediment Under Simulated Rainfall

以福建省安溪县龙门镇崩岗土为对象,通过室内模拟降雨试验,研究在120mm/h雨强条件下,不同秸秆覆盖度(0,25%,50%,75%和100%)和坡度(25°,30°和35°)组合坡面的侵蚀情况。结果表明:(1)秸秆覆盖能够有效延长坡面产流时间,且随着覆盖度的增加产流时间相应延长。(2)在降雨初期,不同条件下的前期径流量随着降雨的进行迅速增加,30°和35°坡面不同覆盖度径流量在降雨中后期起伏较大,30°坡面的径流量明显小于25°和35°坡面。(3)坡面的产沙量变化过程表现为当覆盖度较低时,坡面产沙量较大;当覆盖度处于中等偏上水平时,产沙量始终处于较低水平;当覆盖度达到最高时,产沙量先增加后降低最后趋于稳定。(4)30°和35°坡面径流量的临界覆盖度为50%,不同坡度产沙量的临界覆盖度为75%。(5)可利用经验方程对不同覆盖度和坡度条件下崩积体坡面产沙量进行预测。

With the colluvial deposits in Longmen town of Anxi County, Fujian province, as the research objectives, and through the simulation of rainfall in laboratory, this study intended to disclose the impacts of different straw coverage（0, 25%, 50%, 75% and 100%） and different slope gradient（25°, 30° and 35°） on the slope erosion of colluvial deposits under the condition of 120 mm/h rainfall rate. The main results showed that： （1）Straw mulch could effectively postpone the initiating time of slope runoff, which would also be put off with the increase of straw coverage. （2）At the beginning of raining, the prophase runoff increased rapidly under diffident conditions. The runoff from 30° and 35° slopes under different straw coverage fluctuated significantly at the mid and late stages of rainfall, while the runoff from 30° slope was significantly less than that from 25°and 35° slopes. （3）The process of sediment yield indicated that the sediment yield was larger on slopes with small straw coverage, while kept a lower level on slopes with middle and large straw coverage. When slope straw coverage reached the highest level, the sediment yield increased firstly, then reduced rapidly and tended to be stable finally. （4）The critical straw coverage which functioned well on runoff was 50% for the 30° and 35° slopes, and the critical straw coverage which worked well on sediment yield was 75% under different slopes. （5）The sediment yield under different straw coverage and slope gradient in colluvial deposits could be well predicted by empirical equation.