The Vetiver System and Its Potential Role In Watershed Protection and Rehabilitation.
“Ridge to Reef” programs in small islands are starting to apply VGT because it fits so well into their watershed needs. At the top end vetiver can be used for land rehab and for on farm soil and water conservation. Better for those who live in the upper watersheds and better for those at the lower end because of diminishing floods, more constant stream flow, and reduced sediment flow in rivers. At the bottom end of the watershed vetiver can be used to strengthen coastal defenses by stabilizing and protecting sea dykes. Throughout the catchment vetiver can be used for on farm soil and water conservation, for stabilizing river and stream banks, protecting roads and help ensure non impeded traffic. It can be used for phyto remedial purposes including vetiver wetlands for village and domestic sewage, it can float on ponds to remove blue green algae, it can protect springs and improve water flows to those springs and wells. It provides important habitat for birds, insects, and other wild creatures. Additionally there are biproducts including the leaves and stems used for handicrafts and thatch. Countries like Madagascar desperately need to apply VGT widely for watershed development and land rehabilitation purposes.
Photos 1-4 show what can be done to improve a small watershed when using vetiver. The last photo gives some indication of the improved water balance due to vetiver (Yoann Coppin)
Watersheds in the upper parts of river basins can become the source of major flooding of areas many miles away in the lower parts of the basin, this is particularly so when the upper catchment experiences extreme weather events. Watershed conservation is not only important for hilly areas but also flat areas too as shown in this series of images from (Paul Truong) the Darling Downs in Queensland, Australia. Note this application was applied to black cracking vertisols, and could be applied the many millions of ha of black soils in Asia and Africa.
Photos 5 & 6 Left: Vetiver planted on this farm waterway to control erosion and trap sediment in Australia. Right: Every year at least 50 cm of sediment was trapped
Photos 7 & 8 Left: Vetiver planted on this floodplain to control flood erosion. Sediment was trapped after a major flood. Right: No flood erosion and excellent crop of sorghum after the floodPhoto 9 This sediment (3 ft deep) in this drainage line on a sugar estate in Natal, South Africa, was captured After an extreme rainfall event and came from a neighboring farm that was not protected by vetiver contour hedgerows. The stiff leaves and stems of vetiver withstood the flood, trapped the sediment and continued to grow (Maxime Robert)Photo 10 Australia – instead of a constructed swale this vetiver hedgerow is doing the job at a lower cost.Photo 11. Vetiver planted on the shore of Lake Victoria to stop sediment from a busy fishing market from entering the Lake. Basin authorities should all use vetiver to mitigate a myriad Of soil and water related issues (Imran)Photo 12 Hillside protection in Brazil using vetiver hedgrowsPhoto 13 This gully in Queensland has been effectively stabilized with vetiver (Paul Truong)Photo14 This area in SE Zimbabwe is hot, flat and eroded. Th worst erosion is on the left, porly managed farm lands. Black vertisols, difficult to work, but fertile. It is sending large volumes od=f sediment to the area on the right that a wildlife trust area. A 20 ha pilot project was implemented successfully in 2021 and is now being extended to 1000ha. VGT is the key technology being introduced with hedgerows on the contour 100 meters apart.
Photos 15 and 16 A first year vetiver hedge (recently cut) and the adjacent maize crop. ++ some very happy farmers!
