Management tips for your property
Tablelands Telegraph – December 2021
Bruce Christie, Senior Land Services Officer
Gully erosion can be an unsightly scare on the land and add to nutrient loss and poor water quality downstream. Gully erosion is created when water forms channels, mostly created from some form of “nick” point. This could be a farm track, rabbit hole, or just bare soil. The increased energy scours the soil and removes vegetation. Once the vegetation is removed the gully erosion can move rapidly up drainage lines.
It may be that a gully is not currently active and so it may be best not to disturb it. You can tell if it is active by the amount of grass that has colonised the floor of the gully and whether the gully head is active. If you are not sure or have only owned your property for a short while it may help to take a photo to compare over time. It may also be useful to drive a steel post nearby or include some feature to give a comparison between photos.
Vegetation is the long-term solution to gully erosion. Tussocky grasses can slow movement of water across the surface, while the roots hold the soil together minimising particles moving with the water flow. Stock management in the immediate area, and above the gully is critical to the repair of these sites. If the site is part of a larger paddock a temporary electric fence can reduce grazing pressure and allow tussocky grasses to colonise, while a short crash graze at some time may also be beneficial.
It may be that the gully is beyond these passive treatments in which case you will need to seek expert advice before working on the site as some treatments may worsen the erosion, and some streams are protected with legislation. Some of these treatments may include:
- Stabilising the gully head to stop it moving further upstream. Depending on scale this could be as simple as placing rocks in the site, so it no longer erodes.
- Diversion banks to redirect the water to another point. This may just move the problem to another area. Expert advice would be required in this case.
- A drop structure or damming the site may assist by taking out the energy or flooding out the site. Expert advice would also be required in this case.
Prevention of any erosion is certainly the key. Maintaining groundcover above 70% has been proven to reduce runoff reducing soil and nutrient loss. Also keeping an eye out for any issues and treating before they increase in size is a much easier and cheaper option.