| چکیده انگلیسی مقاله |
Understanding the mechanism of the interrill erosion process is important to develop a process-based interrill erosion model. Six rare earth elements (REEs) were applied in different slope segments and soil layers to track sediment movement and deposition in order to gain insights into the near-surface hydraulic gradient-affected (drainage, saturation, and seepage conditions) interrill erosion processes under three rainfall intensities of 30-, 60-, and 90-mm.h-1, respectively. The results showed that the contribution of interrill soil loss from each tracer segment along the slope was increased firstly and then decreased in drainage-saturation conditions, while that was increased in seepage conditions. The transport by raindrop-induced and overland flow-driven rolling, creeping, and/or sliding was dominant transport mode. The dominant process of interrill erosion was transport-limited in drainage-saturation conditions and detachment-limited in seepage conditions, respectively. In transport-limited process, raindrop-induced transport was more efficient than raindrop impact overland flow-driven transport. However, the raindrop impact overland flow-driven transport was more efficient than raindrop-induced transport in detachment-limited process. The response relationships of sediment transport capacity and soil detachment rate which separated from the interrill erosion rate to near-surface hydraulic gradient, rainfall intensity, slope gradient, and slope length could be better described by power equation respectively (R2 ≥ 0.81, NSE ≥ 0.81). The values of R2 and Nash-Sutcliffe simulation efficiency (NSE) increased by 2.53% to 1840.00% and the average absolute values of the relative error (RME) derived from in this study decreased by 38.03% to 87.21% compared with the existing interrill erosion empirical equations. In addition, the so called interrill erodibility should be further divided into interrill sediment transportability in transport-limited process and interrill detachability in detachment-limited process. |
