黄土区不同地貌部位径流泥沙空间分布试验研究

Spatial distribution of runoff and sediment on the different topography positions of vertical belts in loess region of hilly

黄土丘陵区侵蚀泥沙的来源以及坡沟侵蚀产沙关系等一直是研究的热点难点之一 ,也是争论较多的问题。在梁峁坡到谷坡的坡沟系统中 ,不同地貌部位有对应的侵蚀形式出现。该文采用多坡段组合模型 ,运用人工模拟降雨试验方法 ,研究了黄土区坡面各垂直侵蚀带径流泥沙的空间分布特征及上坡来水来沙的加速侵蚀作用。结果表明 :单位面积与时间产流量排列为谷坡 >梁峁坡下部 >梁峁坡中部 >梁峁坡上部。雨强 0 .5 mm /min时 ,没有沟蚀发育 ;1.0 mm/min时 ,细沟主要在梁峁坡下部 ;1.5 mm/min时 ,细沟伸展到梁峁坡上部 ,谷坡出现滑塌和崩塌等重力侵蚀现象。坡面径流量、产沙量随坡度、坡长、降雨强度变化成正比增长。上坡来水来沙使梁峁坡和谷坡产沙量大幅度增加。

There have been many arguments on and also have been many interests in the source of soil erosion at hilly region of the Loess Plateau and the slope gully erosion sediment production. Erosion patterns correspond to the different topography position from hill slope to gully slope in soil erosion chain in the slope gully system of loess region of hilly and gully. Spatial distribution of runoff and sediment in the vertical belts sections of soil erosion chain was studied by simulated rainfall examination on block diagram combined with multi slope sections, also studied the accelerated erosion of the sediment from the upper slope. Results show that runoff increases from upper slope to lower slope. Runoff per unit area and time increased with the order of the upper hillside, the middle hill slope, the lower hill slope, and the gully slope. Also, all erosion patterns developed well on hill slope with rainfall intensity of 1.5 mm(min) 1and rill erosion extended from bottom of slope to the middle and the upper hill slope, gully slope display the gravity erosion such as slide and collapse. Rill erosion, in contrast, only occurred in the lower hill slope and gully slope with rainfall intensity of 1.0 mm/min, and gully erosion did not developed with rainfall intensity of 0.5 mm/min. Slope runoff and sediment production increase with an increase of slope gradient, slope length and rainfall intensity due to the effect of runoff from the upper slope, sediment yields of hill slope and gully slope increased greatly.