Evolution and spatio-temporal characteristics of slope erosion due to rainfall in Southwest China

Soil in rainy and moist regions is influenced by heavy rainfall, which results in erosion from exposed slopes; local collapse and landslide may occur with the evolution of slope erosion. To determine the time-space effect of heavy rainfall on a slope, an in situ model test of a granite slope that was completely decomposed due to rainfall was conducted. The resistivity profile and surface shape parameters of the slope under continuous rainfall were monitored through electrical measurements and three-dimensional laser scanning. Infiltration and slope erosion evolution were analyzed based on the relationships between erosion rate and resistivity. With an increase in rainfall duration, a creep-type growth trend was observed for rill density on the slope surface with rill density change rates of approximately 0.6%/h, 0.1%/h, and 0.7%/h. A gradual decreasing trend of rill density was observed from the bottom to the top of the slope, and the decrease was approximately three times. When the rainfall duration was 12 h, a step-type growth trend for erosion rate was observed from 8.0-11.3 to 21.8-38.8%, i.e., an increase of approximately three times, indicating a transition from low-speed to high-speed growth in erosion. A gradual decreasing trend erosion rate was observed from the shallow to deep part of the slope; the average growth rates were 33.0%, 15.2%, and 4.9% when the rainfall duration was 16 h.

Automated summary

This study investigates the impact of heavy rainfall on slope erosion by conducting an in situ model test of a decomposed granite slope. The results show that an increase in rainfall duration leads to an increase in rill density on the slope surface and a higher erosion rate. Additionally, a decreasing trend of erosion rate is observed from the bottom to the top of the slope and from the shallow to the deep part of the slope.