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利用室内人工模拟降雨试验,研究了4种设计雨强(33,54,94,125mm/h)、3种设计坡度(5°,10°,25°)在覆盖条件下对紫色土坡面初始产流时间、覆盖保水率和保沙率的影响。结果表明:覆盖条件下初始产流时间相比裸地均有一定的滞后效果,且其初始产流的滞后时间随坡度、雨强的增加而减少。当坡度增大至25°,雨强在94mm/h以上时,其滞后时间逐渐趋于稳定,在1.61~2.84min范围内波动。雨强是影响秸秆覆盖保持水土作用的重要因子,与覆盖保水率、保沙率均在0.01水平上呈显著负相关,且在不同坡度条件下均可以用抛物线进行很好的描述。不同坡度条件下,覆盖的保水率随雨强的增加逐渐下降至14.5%,而其保沙率则只下降至92.25%,相比覆盖的保水作用,其保沙作用更加明显。覆盖条件下,坡度对坡面产流及产沙的贡献率均大于50%,坡度对秸秆覆盖保持水土的作用影响很大。坡度对坡面侵蚀的贡献率在裸地和覆盖条件下均随雨强的增加而呈现减小的趋势,且在相同雨强下,坡度的贡献率在覆盖条件下均大于裸地,在大雨强下(94mm/h和125mm/h)差异明显。
Four kinds of design rainfall intensity (33, 54, 94, 125 mm / h) and three design gradients (5 °, 10 °, 25 °) were used to simulate the initial production of purple soil slope Flow time, covering the water retention rate and the impact of sand holding rate. The results show that the initial runoff time has a certain lag effect compared with bare land under the condition of covering, and the lag time of initial runoff decreases with the increase of slope and rainfall intensity. When the slope is increased to 25 ° and the rainfall intensity is above 94mm / h, the lag time tends to be stable and fluctuates within the range of 1.61 ~ 2.84min. Rainfall intensity is an important factor that affects the coverage of soil and water by straw mulching. It is significantly negatively correlated with the coverage of water retention rate and sand holding rate at 0.01 level, and can be well described by parabola under different slope conditions. Under different slope conditions, the water retention of the cover decreased gradually to 14.5% with the increase of rainfall intensity, while the saponification rate decreased only to 92.25%. Compared with the covered water retention effect, the saponification effect was more obvious. Under the conditions of coverage, the contribution of slope to the runoff and sediment yield was more than 50%. The effect of slope on the soil coverage by straw mulching was significant. The contribution of slope to slope erosion shows a decreasing trend with the increase of rainfall intensity under bare land and cover conditions. Under the same rainfall intensity, the contribution of slope is larger than bare land under cover conditions, Strong next (94mm / h and 125mm / h) significant difference.