Turf is proving itself to be an effective erosion control method.
By Todd Layt
Turf grass is proving itself to be an effective way of minimising and controlling surface erosion. Turf protects the ground from the impact of rainfall and reduces the speed of runoff water. It also holds soil and sediment particles in place and enhances the ground’s ability to absorb water. Research in Queensland is demonstrating turfs erosion control capabilities.
On batters of a gradient less that 33.3 percent turf is showing it is a successful method of erosion control and stabilizing areas of concentrated flows such as channels and drains, provided the flow velocities do not exceed 1.5 m/s. If flows are higher, combining turf with geotextiles seems to be a well proven concept. Some companies grow the turf on netting, or simply lay the turf on site on many different forms of soil strengthening geotextile. Turf alone will trap sediment, but in combination with other mitigation technologies it can also be highly effective. Silt fences, coir logs and erosion socks used on their own have very limited benefits, and are far less effective than you think. Combine them with turf in the appropriate method and the results are greatly improved. Many examples of these techniques can be seen at the demonstration site in Brisbane, with live demonstrations held the last Thursday of every month. To attend contact Lisa Erhart, The Project IDO on 0418 822 108 or email idoec@turfaustralia.com.au
When installing turf in warmer months it only requires a maximum of seven days to bind to the underlying soil. In cooler months it can take a little longer, so the turf can be pegged on slopes. Turf with rhizome’s or underground runners are best, as these varieties provide a three dimensional long term protection, binding the soil to a greater depth. Traditionally Kikuyu and Couch have been popular types for erosion control. However recently Zoysia varieties are also regularly being used due to their ability to better cope with wet feet, their greatly reduced mowing needs, and the extra soil strengthening they provide. Avoid laying Zoysia in winter except in Queensland. Nara Native Zoysia Turf, being a local species, is becoming popular for erosion control particularly amongst native vegetation. Buffalo does filter out sediment very well, but its lack of rhizomes, its cost, and its lower drought tolerance make it relatively unsuitable.
For more technical information regarding the use of turf in combination with other methods for erosion control go to: http://www.ozbreed.com.au/research-papers/erosion-research.html
|
Demonstration of turf being used in erosion control. |
