Impacts of slope morphological evolution on subsequent erosion for a coarse-textured soil

Abstract

Assessing impacts of erosion-induced slope morphological evolution on subsequent erosion based on erosion feedback system is crucial for prevention and control of slope erosion in coarse-textured soil regions. This work aimed to reveal the effect of the evolving erosion morphology on subsequent erosion processes on the granite red soil slope through quantitative analysis. Specifically, we achieved it by conducting long-duration (120 h) simulated rainfall experiments under constant rainfall intensity of 90 mm h−1 and fixed slope gradient of 16.7 % on the soil flume packed with granite red soils to simulate field slope. Results showed that (1) with the evolution of erosion, three erosion phases (sheet erosion, rill erosion, and ephemeral gully erosion phases) varied as the dominant erosion forms; (2) with erosion development, the coverage of quartz gravels enriched on the slope surface increased first (4.60 %-49.17 %), followed by a trend of dynamic erosion–deposition equilibrium (47.68 %-56.74 %); (3) the quartz gravel cover on the surface restrained the slope erosion degree, resulting in loss of fine particles and erosive-reduction in vertical depth of inter-rill and sheet erosion areas; (4) quartz gravels entering the channels inhibited downward erosion, forcing the runoff to intensify lateral erosion, leading to gradual degradation of soil layers and the exposure of erodible subsoils under an accelerated trend. This work provides a reference for the prediction and control of slope erosion in granite red soil regions.