Experimental and Numerical Simulation Study on Erosion Process of Loess Surface

ABSTRACT In the past 20 years, the problem of soil erosion on the Loess Plateau of China has been severe, and the particular sensitivity of loess to erosion by water makes it highly susceptible to erosion. This paper conducted experimental research to quantify loess erosion and to develop corresponding numerical simulation models. The research showed that: (1) during the erosion process, rills appear, and the erosion pattern gradually changes from sheet erosion to rill erosion. The increase in soil moisture content and the decrease in dry density make it easier for erosion rills to form. Slope surface shape not only controls where rills form, but also affects the width and depth of erosion. (2) During the erosion process, the erosion rate curve shows an exponential growth. The increase in soil moisture content and the decrease in dry density accelerate the erosion rate. Similarly, the change in slope shape (with an increase in the number and volume of shallow pits on the surface) also increases the erosion rate. (3) Based on the experimental results, a CFD‐DEM coupled model was developed to simulate numerically the process of erosion. The simulation results showed that there were some differences between experimental results and simulation results. The simulated erosion rate shows three stages of change: gradually increasing stage (sheet erosion), rapidly increasing stage (rill erosion), and remaining stable stage (collapse). The rough model particles make the simulated erosion rate slightly larger, but the growth law is consistent with experimental results, and the erosion rate change in remaining stable stage that the experiment lacks is also in line with expectations. To some extent, the simulation results compensate for the shortcomings of small‐scale experiments and validate the rationality of the CFD‐DEM coupled model method for simulating soil erosion processes.