Reduction of Landslide Risk and Water-Logging Using Vegetation

Abstract

Landslide is a major concern in Bangladesh. The Hill Tracts of Bangladesh are highly vulnerable to rain-cut erosion because of their geological formation, soil characteristics (sedimentary) and deforestation. The cracks in the sandstone allow water to permeate through the layers which causes decrease in shear strength of hill soils leading to landslides. Eroded soil causes clogging in drains and canals in nearby urban areas. Subsequently, in a view to investigate the erosion potential of hill slopes, soil samples were collected from Chittagong and Rangamati hills. The soil is mostly silty or clayey sand which is susceptible to erosion. In this context, bio-engineering technique using vetiver has been selected to reduce erosion potential and water-logging. Efficacy of vetiver in soil erosion has been studied using a model for vegetated slope constructed with hill soil. Performance of slope against rain-cut erosion has been premeditated under uniform artificial rainfall for both bare and vegetated slopes. The sediment yield for bare soil is found to be 47.8 kg/m2 which is almost four times higher compared to the sediment yield for rooted slope (11.6 kg/m2). Therefore, vetiver is effective in reducing erosion, which eventually decreases landslide vulnerability and water-logging in the nearby city areas.