Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

Abstract

Although vegetation is increasingly used to mitigate landslide risks, how vegetation roots affect the landslide threshold of slope has rarely been explored, particularly in the case of lateral runoff. In this study, we established a two-dimensional saturated-unsaturated infiltration equation considering the hydraulic effects of vegetation roots. The analytical solution for the shallow unsaturated two-dimensional coupled infiltration of vegetated slope (VS) was obtained by a Fourier transform technique. The numerical method was used to evaluate the stability of VS caused by four root architectures, the rainfall amount, and the rainfall duration. Subsequently, the transformation law in runoff, vegetation evaporation, and landslide threshold was analyzed. The results indicate that the factor of safety (FOS) increases with increasing drying time and decreases with increasing depth; the minimum FOS is at the junction of the root-rootless zone. Runoff and vegetation evaporation are favorable for the shallow stability of VS. The time of the safe area is 35 h for rainfall amount 500 m in the uniformly root clay slope. Moreover, four landslide threshold curves that reflected the root architecture, rainfall amount, and rainfall duration are developed, which are more realistic than those created using one-dimensional instability modeling.

Comparison of different open‐source Digital Elevation Models for landslide susceptibility mapping

“…The presence and abundance of vegetation also play a role in the impact of precipitation on slopes. Adequate vegetation coverage reduces surface runoff, while plant roots consolidate rock layers, enhancing soil stability and reducing landslide susceptibility (Huang et al, 2021). Furthermore, human activities, such as engineering projects, cultivation and deforestation (or afforestation), greatly influence the stability of the entire system, leading to an increased frequency and magnitude of landslide events.…”

“…I G U R E 1 Study area with landslide and non-landslide points both for training and testing (a: S1, b: S2). [Color figure can be viewed at wileyonlinelibrary.com] vegetation also play a role in the impact of precipitation on slopes.Adequate vegetation coverage reduces surface runoff, while plant roots consolidate rock layers, enhancing soil stability and reducing landslide susceptibility(Huang et al, 2021). Furthermore, human activities, such as engineering projects, cultivation and deforestation (or afforestation), greatly influence the stability of the entire system, leading to an increased frequency and magnitude of landslide events.To incorporate the effects of geology, human activities, climate and vegetation, five factors were selected: lithology, distance to roads, land use, distance to rivers, rain and normalized difference vegetation index (NDVI).…”

Experimental Study on the Influence of Substrate Properties on Rainfall Infiltration and Runoff from Ecological Slopes

“…Slope instability landslides are influenced by many factors [7][8][9], such as rainfall intensity [10], rainfall duration [11], vegetation type [12], topography and initial slope conditions [13], and the purpose of parametric research is to understand the rainfall infiltration law of ecological slopes and to grasp the magnitude of the role played by various influencing factors [14]. In the 1970s, Japan began using small-scale physical models of slopes for experimental rainfall studies [15,16].…”

The Effects of Rainfall, Soil Type and Slope on the Processes and Mechanisms of Rainfall-Induced Shallow Landslides

“…In mountain regions, landslides are often triggered by intensive rainfall [8,9]. Rainfall and infiltration enhance moisture content, which further decreases the matrix suction and soil shear strength [10,11]. Rainfall characteristics are often used as criteria for landslide occurrence [12,13].…”