稀土元素示踪坡面次降雨条件下的侵蚀过程

Slope erosion process tracing in simulated raining with rare earth elements

为定量研究次降雨条件下坡面侵蚀形态的演变过程,该文利用REE-INAA(稀土元素-中子活化分析)方法,将REE元素沿坡面垂直分层布设并结合室内模拟降雨试验,研究了次降雨条件下面蚀和细沟侵蚀的转变和动态发育过程。结果表明:降雨初期坡面主要发生面蚀,细沟出现后,坡面侵蚀将加快加剧,细沟侵蚀深度随之迅速增加。坡面侵蚀中面蚀量约占总侵蚀量的30%左右,细沟侵蚀量占70%左右。单位深度范围内最上层土壤侵蚀量最大,向下依次递减。可以将坡面侵蚀形态演变过程划分为面蚀、细沟发育和细沟稳定3个阶段,各阶段转化都有明显的拐点出现。因此,利用REE-INAA方法可以对土壤侵蚀演变过程进行较准确地定量研究。

For studying the slope erosion type changing process,simulated rainfall was applied by placing rare earth elements on different soil depth across the slope. The results indicated that the main erosion type was sheet erosion in the beginning of rainfall,and serious erosion happened after rill erosion appeared. The percentage of sheet erosion to the whole erosion was about 30% and the percentage of rill erosion was about 70%. The erosion of the first layer was the biggest on unit depth,and then decreased with the depth of soil. Therefore,according to the changing trends of the sheet erosion contribute rate and the rill erosion contribute rate,the erosion on slope could be divided into three phases：main sheet erosion phase,rill erosion developing phase and rill erosion stabile phase. Therefore,REE-INAA method could accurately quantify the processes of soil erosion.