Gullies are common across northern Australia, where the wet season sends huge amounts of water moving over land. Surface water flowing in a line over inadequate ground cover scours soil, forming a channel that could come to be many metres deep.
The starting point is usually an area of disturbed soil, a livestock or vehicle track, or existing erosion. Gullies continue to deepen and can spread up or down slopes.They’re a real danger to animals, people, and vehicles. Gullies divert water from where it’s needed, and they take topsoil, silt and nutrients away from the natural landscape.
Gullies are bad news. But you can turn things around.
We’ve been working with a landowner on a property in the upper catchment of the Einasleigh River, where an alluvial gully was causing serious concern.
NRM Project Officer Marcus Mulholland said this gully system was very large and covered an area of almost 10 hectares.
“Through these remedial works, an estimated 4,790 cubic metres of sediment a year will be prevented from entering the adjacent waterway. This improves the health of the waterway and prevents the mobilisation of sediments into the Gulf of Carpentaria”.
These before and after photos show a dramatic change for the better. So, how was it done?
A series of basins direct overland water flow through rock check dams. They reduce water velocity, protecting surface soil from erosion. The dams also trap mobilised sediments, which settle behind the wall, instead of going into the nearby river system.
Then, it’s essential to establish strong vegetative ground cover with a mixture of grass species. This helps the basins do their job while reducing raindrop impact and overland flow, further protecting the soil top layer from erosion.
“This was a very expensive exercise, so the key message here is to address erosion early by employing good land management practices and maintaining strong ground cover”, Mr Mulholland said.
This project was jointly funded under the Queensland and Australian Governments Disaster Recovery Funding Arrangements (DRFA) #DRFA-Qld