Erosion Control

Regularly assess erosion-prone areas, as small areas cost less to repair compared to major outbreaks. In areas prone to tunnel erosion be particularly aware of small fans of silt appearing on slopes. These are often the first indication of tunnel erosion. Maintaining ground cover (preferably over 70%) is the best insurance for erosion as it reduces surface water flow and its velocity (The faster the water moves, the less chance of infiltration and increased likelihood of topsoil loss) Maintain vigorous perennial pastures and plant fast growing trees and other vegetation in on and above erosion areas (i.e. gullies, drainage lines, slips) to help reduce excess water in the soil.

• Planting out an eroded area may result in the small loss of land (usually unproductive anyway if eroding) in the short term but will save a larger area for the future. Eroding land takes with it valuable topsoil and nutrients. Pasture around the area may improve with the tree planting and be more productive than the land lost.

• If undertaking erosion control and revegetation works, fence the area to protect the gully from stock until restoration is complete. Lightly graze for the first 2-3 years to allow the pasture to develop and produce a strong root system which will bind the soil together and maximise water use.

A tunnel erosion site that has been fenced and re-vegetated. Photographs by: Rawdon Sthradher (Fine Focus Photography).

Soil creep or terracing (often mistaken for stock tracks across a hill face) is another form or mass movement. As terracing only occurs on the steepest slopes, it is advisable to fence these into different land classes so that they can be managed separately Do not fill eroded gullies with solid objects such as old drums, car bodies or concrete. This only creates further erosion by directing water around the objects and removing even more soil.

Related Links - DPI Landcare Notes
Landslips
Stream Bank Erosion
Gully Erosion
Tunnel Erosion
Trickle flow pipes for gully erosion control

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