Performance of a Test Levee Slope using Bio-Engineered Stabilization on High Plasticity Clay

According to the United States (US) Geological Survey, rain-induced landslides are the most frequent and widespread landslides that occur in the US. Stabilizing levee slopes to prevent shallow landslides–occurring within the upper six to eight feet (1.8 to 2.4 meters) of the slope–addresses common problems associated with levees constructed of high plasticity clay. Following precipitation, water can infiltrate the slope and create perched water zones, which decreases stability. Vetiver grass planted on levee slopes can mitigate the impact of precipitation. Vetiver has demonstrated effectiveness as a protection to improve weak, weathered, high plasticity clay, thereby reducing the potential of shallow failure development. Vetiver is known for its deep roots, which can extend twelve feet deep. Vetiver was planted at one foot center-to-center spacing on a 40 ft (12.2 m) by 30 ft (9.1 m) study area of a test levee made of Mississippi Yazoo clay and monitored for two years. A finite element method (FEM) analysis considered the effect of 100 and 500-year precipitation intensity-duration-frequency (IDF) curves of Jackson, Mississippi, on the stability of a comparable levee slope. This research demonstrates that vetiver grass is compatible with Yazoo clay and naturally combats rain-induced shallow failures on levees. At an installation cost of five US dollars per square foot, it is economically viable. Communities abroad have also educated residents on the use of vetiver regarding stormwater and erosion control, particularly in landslide prone communities, and to reduce pollution in urban environments, due to its ability to sequester carbon. With increasing precipitation in Mississippi, vetiver’s use on existing and proposed maritime and multimodal transportation infrastructure holds promise as a climate resilient solution.