Monitoring Soil Resistivity in Highway Slopes Stabilized with Vetiver Grass

The intensity of the heaviest downpours has risen by roughly 20% over the past century, and this trend is expected to persist. Fluctuations in temperature, precipitation, sea levels, and coastal storms caused by climate change will increase the vulnerability of infrastructure across the United States. Southern states like Mississippi, Alabama, Texas, and Louisiana face greater challenges due to the abundance of expansive clay soil. During the wet season, the rainwater infiltrates into the soil and triggers the volume expansion. In drying periods, the soil shrinks significantly, and desiccation cracks are formed within the soil. Highway slopes built on expansive soil are, therefore, prone to rainfall-induced failure. The current study investigates the role of Vetiver grass, a nature-based solution, in improving the soil moisture condition of highway slopes. Vetiver is a deep-rooted long grass system that can draw out a lot of moisture when planted in the soil. It improves the soil moisture condition and adds additional shear strength to the soil. The study selected a highway slope near Jackson, Mississippi, where a section was stabilized with Vetiver grass. Another section was considered as a control section where no Vetiver was planted. Electrical resistivity imaging (ERI) tests were done seasonally to monitor the soil moisture profile along the slope depth. Resistivity values along the depth for both the planted and control sections were compared to evaluate the performance of Vetiver grass. It was observed that the planted section has higher resistivity to a certain depth, denoting lower moisture content and reduced perched zone, compared to the control section. The study highlights Vetiver grass as a climate-resilient and proactive solution for slope stabilization, which can be a game changer in addressing the challenges posed by climate change.