The REE Tracer Method for the Study of Rill Erosion Process on Loess Sloping Surface
黄土坡面细沟侵蚀过程的REE示踪

By the rare earth elements (REE) tracer method, four REE (Ce, Sm, Nd, Dy) were used to study the changeable process of rill erosion on loess sloping surface in runoff scouring experiments. During different stages, the erosion pattern and characteristics are different. Generally, hi the process of the rill development, the soil erosion amount hi the bottom section was larger, and it decreased with the increase of the flow discharge, but the situation is on the contrary to the top section, which indicated that the influence of flow discharge outweighed the gradient on the rill erosion; the rill relative erosion amount hi the bottom section obviously decreased from 92% to 37%, but the other three sections gradually increased from 4.7%, 0.25%, 2.14% to 29 %, 17% and 23% respectively because of the headcut erosion. Results from the experiments have also shown that the REE tracer method can be used not only quantitatively to determine rill erosion amounts in different slope sections, but also to reveal the changeable trend of rill relative erosion amounts. It provides a reliable and effective method for the research on rill erosion process.