模拟降雨条件下碱性坡地土壤侵蚀试验

 采用室内人工降丨射模拟试验，研究降雨强度为50 mm/h时不问坡度（5°、15°、25°)和不同土壤（土壤的可交换钠比例ESP值分别为2.4和25)对土壤人渗率和侵蚀缺的影响。结果表明：1)不问坡度和不同土壤的径流模数随降雨历时急剧增加，后于平稳，人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，入渗率和累计人渗量都随着坡度的增大而增加，侵蚀产沙坩随笤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，稳定人渗率和累计人渗量随卷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，核蚀产沙量随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。

Erosion of sodic slope under the condition of simulated rainfall

A group of rainfall simulation tests were conducted to quantify the effects of slope and soil with different exchangeable sodium percentage（ESP） on the water infiltration and soil erosion.Three different soil slope degrees（5°,15°,25°） and two ESP levels of soils（2.4 and 25） in the same rainfall intensity（50mm/h） were designed in this study.Results indicated that： 1） For each treatment,runoff modulus increased rapidly at the beginning of rain,then arrived at a steady value over time,and soil infiltration rate and sediment yield decreased over rain duration;2） In the same ESP level,soil infiltration rate and accumulated infiltration increased with the increase of slope degree.Soil erodibility increased with the increase of slope firstly,then decreased as the slope being 25°,which indicated that there was a critical erosion slope degree existing in the range of 15°-25°;3） In the same slope degree,runoff modulus increased with the increase of ESP of soil,while steady infiltration rate and accumulated infiltration decreased with the increase of ESP of soil;4） The effects of ESP levels of soil on soil erodibility changed with slope degree.Soil erodibility decreased with the increase of ESP level of soil under the slope of 5° and 15°,however,soil erodibility increased with the increase of ESP of soil under the slope of 25°.It is suggested that we should pay more attention to erosion of higher ESP level of soil at greater slopes（15°）.