REE示踪坡面侵蚀过程研究

SOIL EROSION PROCESSES ON SLOPING LAND USING REE TRACER

在观测年度气候条件下,坡面产流初始阶段片蚀是坡面侵蚀的主要方式,试验期间的三次降雨片蚀分别占坡面总侵蚀量的71%、48%、49%,表明坡面侵蚀处于片蚀-细沟侵蚀演变的初期阶段;同时随着降雨的进行,细沟侵蚀量在不断增大,表明坡面由片蚀为主逐渐过渡到片蚀向细沟侵蚀转变的阶段。对次降雨条件下坡面不同部位的侵蚀泥沙来源研究表明：无论片蚀绝对量如何变化,坡面表层上段的相对侵蚀量始终不大于10%,表明坡面片蚀的来源主要集中在坡面下部;降雨结束后对不同坡段的细沟相对侵蚀量比较分析后发现,不同坡段的相对侵蚀量结果分别为：距坡脚0-1米坡段16%;2-4米坡段6%;5-9米坡段3%,三段的侵蚀量之比约为5∶2∶1,表明细沟侵蚀的主要来源集中在距坡脚4米段内。

Sheet erosion is the main performance in the slope soil erosion process at the primary stage of natural rainfall. For three times of rainfall during experiment, the ratios of sheet erosion to total erosion account for 71%,48% and 49% respectively, which showed that the sloping erosion was still at the primary stage from sheet erosion to rill erosion. With the rainfall going, the rill erosion amount increase. It showed the soil erosion was changing from sheet erosion to rill erosion. The sources of sediment from different sections of the plot were analyzed, and the results indicated that whatever the sheet erosion changed, the ratio erosion of upper part of surface soil was always lower than 10%. Sheet erosion came mainly from the lower section of surface soil. With the ratios to the amount of total rill erosion changes, the rill erosion amount of each section regularly changes too. The general conclusion is that when the rainfall ends, relative erosion of different slope element to the foot of slope is： 1 meter away accounts for 16%, 2 ~4 meters away is 6% and 5 - 9 meters away is 3%. The ratio of rill erosion amount of these three slope element is 5 ： 2 ： 1, which shows the rill erosion amount are mainly from the slope element of 4 meters from the foot of slope.