Cooktown Rd

VETIVER GRASS FOR EROSION AND SEDIMENT CONTROL Paul Truong, DNR, Brisbane and Errol Copley, Cannon Park Lawns, Cairns

Vetiver Vetiver Grass Grass Technology Technology (VGT) (VGT) was was first first developed developed for for soil soil and and water water conservation conservation in in agricultural agricultural lands lands but but due due to to the the extraordinary extraordinary characteristics characteristics of of Vetiver Vetiver grass, grass, VGT VGT has has been been used used world world wide wide as as aa very very effective effective and and economical economical method method for for erosion erosion and and sediment sediment control control in in civil civil construction. construction. The The Department Department of of Main Main Roads Roads has has successfully successfully used used VGT VGT on on the the Lakeland-Laura Lakeland-Laura and and Cooktown Cooktown Development Development roads roads for for batter batter stabilisation stabilisation and and runoff runoff control. control. SPECIAL CHARACTERISTICS Vetiver is a sterile and non evasive grass with no above or underground runners 3.3m in one year

It is tolerant to drought, frost, fire, water-logging, disease and pest. It is tolerant to extreme soil conditions such as acidic, alkaline, saline and sodic, as well as aluminum and manganese and heavy metal toxicities.

Stiff and erect stem capable of trapping both fine and coarse eroded sediment

Dense and finely structured root system binds the soil on steep slopes against erosion

Deep and penetrating root with tensile strength of 1/6 of mild steel reinforcement

In situ cutting on a fill slope showing 3.6m root growth after 8 months in Malaysia.

Lakeland - Laura Road This cut batter at Split Rock was badly eroded within a few months after earth work completion

Cooktown Development Road Vetiver planted to protect the batter on this highly erodible sodic soil

CONCLUSIONS Vetiver hedge can be rapidly established in arid conditions and poor soils with little if any nutrients

Strong root reinforcement of vetiver grass holds up this wall of soil against water erosion

Water flow Lakeland - Laura Road Highly unstable culvert inlet, rock is the traditional and preferred method of stabilisation, but it does not work on this highly erodible soil at Split Rock

Lakeland - Laura Road On the highly

Lakeland - Laura Road Eight months

Lakeland - Laura Road On wide table drain,

erodible soil at Split Rock, rock check dams on wide table drain do not work as water just cut through the side.

Once established vetiver hedges are maintenance free and withstand arid and dry season conditions including bush fires. Encourages sheet flow and reduced water run-off velocities resulting in natural vegetation re-growth and prevention of erosion.

Cooktown Development Road Same Lakeland - Laura Road The same Split Rock site, three months after vetiver planting

batter, eight months after planting. Vigorous growth will protect this batter against high intensity rain during the wet season.

Very cost effective, with savings ranging from 73% for culvert protection to 64% for table drain and other miscellaneous protection works and 60% for road shoulder protection.

after vetiver planting, this culvert is now fully protected against high intensity rain

short rows of vetiver planted on contour line , spread water flow, reduced flow velocity and trapped sediment