Modeling Soil Erosion With Evolving Rills on Hillslopes

Abstract

Whereas current erosion models are successful in quantitative estimates of soil erosion by water flow, modeling the coevolution of geomorphological features, particularly rill network properties and soil erosion on hillslopes, is still a major challenge. In this study, we propose a rill evolution modeling approach and combine it with a rainfall-runoff and soil erosion model to simulate the feedback loop of hillslope geomorphic development and soil erosion processes. Rill evolution is mainly characterized by three rill network attributes, rill density, orientation angle, and rill width, all modeled with physical equations. The entire rainfall-runoff-erosion and rill evolution model is tested against a set of rill network evolution and soil erosion data from an experimental hillslope subjected to successive rainfall events. The simulated spatial and temporal variations of rill network characteristics and soil erosion agree well with the measured data. The results demonstrate that the three rill network characteristics continually alter the partitioning of interrill and rill flows and affect the interrill and rill flow erosivity and soil erosion, which in turn modify the rill geometry and rill network planform. Comparatively, existing approaches such as Water Erosion Prediction Project (WEPP) that ignore the rill evolution processes largely underestimate the hillslope soil erosion when using time independent model parameters. Moreover, a sensitivity analysis indicates that both the rill evolution and soil erosion processes are sensitive to the rill evolution parameters, rainfall intensity, and slope angle. These results can inform the development of general geomorphic evolution and soil erosion models on evolving rilled hillslopes.

An improved cellular automata model for soil erosion in coastal areas based on discrete physical variables

“…Model simulation is an important approach to improve insight into the mechanism behind the soil erosion process. Many models have satisfactorily predicted soil erosion processes at different spatial and temporal scales, such as WEPP (Wu & Chen, 2020), USLE (Alewell et al, 2019), RUSLE (Mondal et al, 2017), and SWAT (Nearing et al, 2005). However, these models also have some drawbacks.…”

SMODERP2D—Sheet and Rill Runoff Routine Validation at Three Scale Levels

“…(ii) The angle of the rill flow direction and the slope direction may differ due to the microtopography during the initial stages of rill development. This may also cause a difference between a modelled rill and a measured rill, although this is less pronounced for the later stages of rill network development [58,59]. It has also been shown that DTM in fine resolution can predict rill development well [60].…”

Characterization of Surface Runoff Pathways and Erosion Using Hydrological Attributes Under Simulated Rainfall

“…Also, Helming et al (1999) found that the small-scale drainage network of eroded slope runoff had similar characteristics to the river system when Horton's law and fractal Feature methods were utilized (Fang et al, 2018). Wu and Chen. (2020) believed that if the similarities exist, the knowledge that has been obtained at the river scale can be used to understand and simulate the rill network process.…”