Field Evaluation of Soil Shear Strength with Vetiver

The application of Nature Based Solution (NBS) for slope stabilization and erosion control can offer transformative benefits due to low cost and green alternatives. However, the acceptance of the NBS is low due to a lack of understanding of the mechanistic principle for slope stabilization. In this study, Vetiver grass which is one of the potential nature-based solutions for slope stabilization has been evaluated for the shear strength parameters. Slope repaired with Vetiver grass is thoroughly examined using Electric Resistivity Imaging (ERI) and novel field scale direct shear testing. As a part of the study, collected borehole samples from Vetiver planted slope have found roots up to 3 m of depth. Nondestructive testing using Electrical Resistivity Imaging (ERI) had shown Vetiver has increased the resistivity (ranging from 4 to 60 ohm-m) compared to the soil without Vetiver (ranging from 2 to 28 ohm-m) indicating reduced moisture content in presence of Vetiver. The field scale direct shear test performed on Vetiver-planted soil demonstrated that Vetiver increases the soil shear strength two times compared to the section without Vetiver. Overall, it is seen areas reinforced with Vetiver roots impact positively on soil shear strength. The findings highlight that Vetiver plays a dual role in stabilizing slopes by lowering soil moisture through evapotranspiration and offering mechanical reinforcement through its wide, bushy root system. By improving soil strength and stability, Vetiver becomes a transformative solution for slope repair offering a sustainable and climate resilient approach for slope repair.