Teaming up with landholders to lock down soil with both natural and engineered solutions!
A concrete mat chute handles its first summer storms and were able to witness firsthand how well this approach works in mitigating large-scale bank erosion.
Find out more about how this and other solutions can help us lock down that soil!
Flood resilience |
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Protects agricultural and environmental values |
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Cleaner water |
Our amazing team was recently in the field to check out the performance of a concrete mat chute installed for the Healthy Land & Water’s longstanding project Healthy Catchments Program.
The team delivered a whopping 18 engineering projects across ten properties in 2023. The concrete mat was utilised at one of the properties as a form of hard infrastructure designed to mitigate large-scale gully erosion.
What is the mat’s role at this site?
The concrete matting was installed to repair an eroding “head cut” and create an armoured chute where water can safely drop down to the lower section of the gully.
A head cut occurs when fast flowing water exposes and cuts away at the soil of the stream bed, creating an abrupt drop that can be a few centimetres to meters high.
In this property’s case the head cut of 2.7m was removed through earth works, installation of the concrete mat and the addition of rocks at the top and bottom of the chute to hold the chute in place.
The matting extends a couple of meters above the bottom of the stream bed ensuring stability of the matting even during intense rainfall and inhibiting water from creeping underneath.
This solution is aided by vegetation growth where roots weave through the base of the matting creating a web that is harder for rushing water to penetrate and move.
Concrete matting and chute being secured with rocks at the property.
Measuring performance
The aim of the site visit was to run a post work check and assess how well the concrete mat chute we installed last year performed during recent large rain events.
Our team looked for signs of any continued erosion along this area of the stream and the water flow has affected the stream bank and stream bed.
This helps us decide on whether there is a need for more works and what the next steps might be. We looked at the survival rate of vegetation that was planted to assist with reducing flow rate and how the mitigation strategies we used affected the stream flow.
More than one solution against erosion
To best manage the erosion in this area, other mechanisms have also been deployed upstream and downstream of the concrete chute:
- Further downstream there has been the addition of pile fields that help redirect the flow and slow down fast-moving water. This helps to build up sediment in these areas and reduces the damage done to riverbanks.
- Upstream a leaky weir has been installed, this helps reduce the flow of water upstream of the head cut. Leaky weirs are natural structures that are engineered to slow the flow of water from flood plains into streams and creeks. This occurs through the slow filtering of water through vegetation, gravel, rock and clay.
The leaky weir upstream has also increased diversity and condition of vegetation in the flood plain where water is being held for longer periods due to the weir’s ability to slow down water flow.
The additional benefit was that the landholder has noticed improvement in stock health.
This successful project would have not been possible without the landholder’s and commitment to reducing erosion and creating resilience for the area and beyond.
We would also like to thank our long-time partner and suppliers Klan Bros Earthmoving and Australian Concrete Mats.
Read more about the full Healthy Catchment Program, which has been delivering since 2010 here.
Acknowledgement
This program in all its phases has been funded by the Queensland Government's Department of Environment, Science and Innovation and runs in collaboration with all the landholders in the targeted areas.