Research PaperA 3D model applied to analyze the mechanical stability of real-world forested hillslopes prone to landslides

- Terminalia ivorensis is the best tree species for reforestation of unstable hillslopes.
- Tree groupings of high density at the bottom and the half-height of hillslopes significantly improve their stability.
- Randomly distributed heterogeneous vegetation stand improves the factor of safety.

This paper is dedicated to a numerical simulation using a 3D model applied to analyze a hillslope's stability in an ecological area in Togo. The 3D model is applied to two natural slopes prone to landslides located in Atakora mountains. The slopes are covered by a randomly distributed heterogeneous vegetation. There were four species of timber and one species of firewood present on the studied sites. Samples of soil and root systems were collected and tested in the laboratory in order to determine their properties which were then used as entry parameters for the 3D numerical model. The study examines the influence of natural forest stands and the morphology of the root system on slope's stability. It was noticed that, close to the tree's trunk, the additional cohesion due to the presence of the roots had a significant influence on the improvement of the slope's stability. Moreover, the depth of the root system as well as spatial repartition and the density of trees on a given site have a major impact on the stability of a hillslope. The model proposed here can be used as a decision-making tool in elaboration of forest management plans and strategies.