Installing the Vetiver System (VS) can help with slope stabilization; landslide prevention on roadsides, railways and bridges; silt/sediment control in culverts and drains; dealing with point-source erosion caused by improper drainage among others. For this reasons it is an important component when it comes to transport infrastructure development. What follows is an explanation of how Vetiver grass is specifically used in infrastructure development.
Protection of cut and fill batters from erosion: Without protection the cut and fill batters constructed in highly erodible soils would be easily eroded by high intensity rainfall during the wet season. In many cases these soils are also deficient in nutrients which make stabilization by vegetative means very slow and difficult. Given that Vetiver grass can withstand extreme soil conditions, it can grow in these soils and its extensive and thick root system (can reach 3.6m in 12 months) binds the soil making it difficult to dislodge. Initial installing of a single vetiver hedge on the edge of the road shoulder encourages the establishment of natural vegetation down the steep fill batter.
Affordable and natural protection of culverts, riprap, rock structure and check dams – The steep slope above culverts is easily eroded, compromising road shoulders, culvert wing walls and culvert aprons. Attempts to protect fill batters, batter chutes and culverts with traditional methods such as riprap rock is expensive and often fails. When planted around rock structures, vetiver grass hedges with its deep root systems prevent these structures from being undermined. Vetiver is very effective in protecting rip-rap rock structures, rock check dams and culverts.
Prevention of gully erosion that can compromise road pavements/shoulders: Gully erosion on roads is very severe and if left unchecked it can undermine adjoining road pavements. Any movement of water beneath the road pavement on highly erodible soils can wash out fine soil particles leaving voids that could cause the pavement to eventually collapses and compromise the road. The dense hedges that result from the installation of a Vetiver System, can trap gravel moving gravel, preventing the formation of voids under the road shoulders thus strengthening the road. When planting in short rows on contour lines along the table drains, vetiver hedges encourage low velocity sheet flow, trap sediment and promote re-establishment of natural vegetation between the hedges, which further reduce the risk of erosion.