摘要
采用室内人工降雨模拟试验,研究降雨强度为50mm/h时不同坡度(5°、15°、25°)和不同土壤(土壤的可交换钠比例分别为2.4和25)对土壤的入渗率和侵蚀量的影响。结果表明:1)不同坡度和不同土壤的径流模数随降雨历时急剧增加,后趋于平稳,入渗率和侵蚀产沙量随降雨历时急剧减小,趋于某一稳定值;2)土壤ESP值水平一定时,入渗率和累计入渗量都随着坡度的增大而增加,侵蚀产沙量随着坡度的增大先增加,后减小,在15°~25°之间存在着侵蚀的临界坡度;3)坡度一定时,径流模数随着ESP值的增加而增加,稳定入渗率和累计入渗量随着ESP值的增加而减小;4)土壤的ESP值水平对侵蚀产沙量的影响随坡度不同而不同,坡度为5°和15°时,同一坡度的侵蚀产沙量随ESP值的加大而减小,当坡度为25°时,侵蚀产沙量随ESP值的加大而增大,说明坡度较大时,土壤ESP值的增大更容易引起土壤侵蚀。
A series of rainfall simulation tests were conducted to quantify the influences of soil slope and Exchangeable sodium percentage(ESP) on the infiltration and erosion of soils.Three soil slope(5°、15°、25°),2 ESP levels of soils(2.4 and 25) and same rain intensity(50mm/h),were used in the experiment.The results indicated that;1) For every treatment,runoff modulus of slope field were dramatically increased at the beginning of rain,then arrived a steady value with time,and soil infiltration rate and sediment concentration decreasing with the increase of rain;2) Soil infiltration rate and accumulated infiltration increased with increase of slope angle,soil erodibility increased with increase of soil slope firstly,then decreased as the soil slope come to 25°,which indicated that there was a critical erosion slop in the range of 15°- 25°;3) Runoff modulus increased with the increase of soil ESP,while steady infiltration rate and accumulated infiltration decreased with the increase of soil ESP.the effect of soil ESP levels on soil erodibility changed with the soil slope.Soil erodibility decreased with increase of soil ESP under the slope of 5°and 15°,however,soil erodibility increased with increase of soil ESP under the slope of 25°.The results suggested that we should pay close attention to erosion of higher soil ESP level at greater land slopes(> 15°).
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