How effective is vegetation in reducing gravity erosion on loess gully sidewall under intense rainfalls?

Abstract

AbstractVegetation has long been recognized as an efficient way of preventing soil erosion; however, the effects of plants on gravity erosion are still broadly unknown, especially under heavy rain conditions. In order to evaluate their influences on gravity erosion, a series of rainfall simulation experiments were performed on a model of the loess gully sidewall, with a height of 1.5 m anda slope gradient of 70°. The experiments were divided into two groups––bare land models (BLMs) and shrub land models (SLMs)––for inter‐ and intragroup comparison, respectively. The experimental results reveal that shrubs had different influences on the varied types of gravity erosion on the gully sidewall. The average landslide volume was 42% greater in the SLMs than in the BLMs, while the average avalanches and mudslide volumes in the SLMs were 50 and 36% less, respectively. Additionally, the average amount of erosion after rain in the SLMs was 33.17 × 103 cm3 more than that in the BLMs, indicating that the vegetation may increase the occurrence of mass failure after a heavy rainfall. Compared with the anchoring effect of vegetation root, the change in soil water resulted from vegetation on the slope had a relatively great effect on aggravating the gravity erosion under heavy rainfalls. The experimental results suggest that the shrub restoration measures can be used to mitigate erosion in the areas experiencing frequent debris flows and hydraulic movements on the Loess Plateau, China.