: Many researchers have evaluated the influence of vegetation cover on slope stability. However, due to the extensive variety of site conditions and vegetation types, different studies have often provided inconsistent results, especially when evaluating in different regions. Therefore, additional studies need to be conducted to identify the positive impacts of vegetation cover for slope stabilization. This study used the Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) to predict the occurrence of landslides in a watershed in Jinbu-Myeon, Pyeongchang-gun, Korea. The influence of vegetation cover was assessed by spatially and temporally comparing the predicted landslides corresponding to multiple trials of cohesion values (which include the role of root cohesion) and real observed landslide scars to back-calculate the contribution of vegetation cover to slope stabilization. The lower bound of cohesion was defined based on the fact that there are no unstable cells in the raster stability map at initial conditions, and the modified success rate was used to evaluate the model performance. In the next step, the most reliable value representing the contribution of vegetation cover in the study area was applied for landslide assessment. The analyzed results showed that the role of vegetation cover could be replaced by increasing the soil cohesion by 3.8 kPa. Without considering the influence of vegetation cover, a large area of the studied watershed is unconditionally unstable in the initial condition. However, when tree root cohesion is taken into account, the model produces more realistic results with about 76.7% of observed unstable cells and 78.6% of observed stable cells being well predicted.
Numerous annual slope failures are induced by heavy rainfall during the monsoons, especially in developing countries in Asia. The authors have developed a simple method to predict rising groundwater levels in natural slopes at a relatively shallow depth based on parametric studies conducted using the finite element method. An assumption of a semi-infinite homogeneous slope was adopted in the analysis. Addtionally, the authors numerically modelled the vertical infiltration and the lateral seepage flow. Using this method implies that the finite element analysis is not mandatory in the evaluations of practical slopes. Such a simplified approach helps avoid time-consuming tasks in rigorous computations. However, a semi-infinite assumption used in the developed method may provide us with unsuitable solutions, particularly in cases where the slopes include heavily terraced topography with local small cliffs, because theoretically, the first slope failure tends to occur in steep slopes, like the edge of a rice terrace, even though they are very small cliffs. Nevertheless, these local solutions do not affect the conclusions for disaster risk reduction. Moreover, such unsuitable alternatives must be eliminated during analysis. To address this matter, the current study proposes a novel concept of specific lengths. This procedure provides a representative length within the specified length range. The averaged slope gradient is defined by focusing on the secant lines between each topographical grid, while those defined outside the specified range – for example, local cliff angles – are ignored in the slope stability calculation. Consequently, the proposed concept was confirmed to be efficient and can be applied to evaluate the terraced rice fields in Sapa, northern Vietnam. In the past, this area had experienced rainfall-induced slope failures; hence, the proposed method may be able to simulate these occurences. The proposed concept’s effectiveness when applied to terraced fields should continue to be verified through case studies conducted in areas with extensive smallterraced topography.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.