Through simulation of rainfall in laboratory, the impacts of different straw coverages (0, 25%, 50%, 75%, 100%) and different slope gradients(25°, 30°, 35°) on the slope erosion of colluvial deposits were disclosed under the condition of 60 mm/h rainfall rate. The main results showed that: 1) The initial time of runoff under different conditions changed from 49 s to 913 s. The initial time of runoff would be putted off with the increase of straw coverage under the same slope gradient. The initial time of runoff was longest at 35° but shortest at 30°. The initial time of runoff was positively correlated with straw coverage. 2) At the beginning of raining, the runoff ratios increased rapidly in a short time, then slowed down gradually. The range of runoff increased with the increasing slope. 3)The runoff ratio was higher at 30° than at 25° and 35° under the same straw coverage. The critical straw coverage of sediment yield was 50%.%通过室内模拟降雨试验,研究60 mm/h雨强条件下,不同秸秆覆盖度(0、25%、50%、75%、100%)和坡度(25°,30°和35°)组合崩积体坡面的侵蚀状况.结果表明:①不同条件下崩积体坡面初始产流时间在49 ~ 913 s;同一坡度条件下,崩积体坡面初始产流时间随着覆盖度的增加而延长;同一覆盖度条件下,初始产流时间35°>25°>30°;坡面产流时间与秸秆覆盖度呈线性正相关关系.②崩积体坡面径流量的变化过程具有如下几个特征:第一,在降雨初期,坡面径流率在短时间内迅速增加,之后趋于平缓;第二,坡面径流量的起伏变化幅度随着坡度的增加而增大;第三,同一覆盖度条件下,30°坡面的径流率大于25°和35°坡面.③崩积体坡面产沙量存在临界覆盖度,值为50%.
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