黄土高原坡沟系统侵蚀产沙过程的REE示踪研究

Using REE Tracers to Measure Erosion Sediment Yield Process of Slope-gully System in Loess Plateau

利用室内概化的坡沟系统模型,结合REE示踪技术,采用放水冲刷试验,对黄土高原坡沟系统侵蚀产沙过程进行了深入研究。结果表明,坡沟系统的坡面侵蚀速率大于沟坡的侵蚀速率,即坡面侵蚀较沟坡侵蚀剧烈;在本研究设计的流量范围内存在一个临界流量Q=12 L/min,当冲刷流量小于该值时,起始侵蚀率随流量的增大而增大,当冲刷流量大于该值时,起始侵蚀率随冲刷流量的增大而减小;相同流量下,随着冲刷历时的延长,其侵蚀率呈波动变化趋势,陆续达到最大,然后又逐渐减小,而且随着流量的增大,La元素示踪带和Eu元素示踪带侵蚀率达到最大的时间越来越短。

The process of erosion sediment yield of slope-gully system in Loess Plateau was studied by using slope-gully system physical model and runoff scouring method, integrating rare-earth element tracing technology. The results indicate that erosion rate of slope-gully system in the slope is bigger than it in the gully, that is to say, slope erosion is more serious than gully erosion. In the range of experimental flow discharges, there is a critical discharge. Erosion rate is increased with the flow increasing when the flow is less than the critical value. Erosion rate is decreased with the flow increasing when the flow is greater than the critical value. And the critical value is 12 L/min. Erosion rate is fluctuated with the scouring duration when the flow is uniform. Initiation erosion rate is increased and the time that erosion rate achieved the maximum is shorter with the flow increasing. Initiation erosion rate is increased and the time that erosion rate achieved the maximum is shorter with the flow increasing.