Flooding impacts the Brisbane River Catchment

Flooding impacts the Brisbane River Catchment

23.02.2015 - Posted by Misko Ivezich
Just before Christmas last year the Queensland Government announced the Resilient Rivers program, which will form the Brisbane River Improvement Trust (see Brisbane Times article). The Resilient Rivers program aims to coordinate efforts to improve catchment management in the Brisbane River catchment.

The Brisbane River is of high economic value to South East Queensland. It supplies the majority of drinking water to the area, flows into Moreton Bay, is a key landmark within the CBD and is an important part of major social events for Brisbane residents (e.g. Riverfire). The flood events in recent years have made everyone more acutely aware of the problems the river faces. Millions of tonnes of sediment have been eroded from the catchment, resulting in significant water treatment costs, loss of dam storage, further degradation of Moreton Bay and risks to Port of Brisbane operations.

Bank erosion on the Mid Brisbane River; effects of flooding
Bank erosion on the Mid Brisbane River – the ute provides an indication to the magnitude of the erosion 

The majority of the sediment has come from channel erosion. In the last few years we have been involved in a number of projects across the Brisbane River catchment and have developed a good understanding of the problems in the system. Major geomorphic changes are occurring throughout the catchment, generating significant sediment loads and resulting in loss of valuable land. These changes are primarily occurring due to the degraded nature of the riparian vegetation in the system.

Bank erosion on the Mid Brisbane River; effects of flooding
Bank erosion on the Mid Brisbane River (note two people standing on top of the bank)

Some great work has been done restoring unstable sites across the catchment. However ultimately the long-term reduction in sediment loads will require reach-scale revegetation programs over tens of kilometres. Herein lies one of the major issues faced in the Brisbane River catchment – the bed, banks and riparian zone are often owned by private landholders. While landholders may be supportive of site-scale bank stabilisation works to address a clear and visible threat to their land, they can be less likely to support large-scale revegetation programs that will require them to forsake substantial areas of their valuable land.

Bank erosion on Lockyer Creek; effects of flooding
Bank erosion on Lockyer Creek

While this riparian land is of significant value to each individual landholder, it is also of immense value to the people of South East Queensland. Future investment in river restoration works should recognise this. Incentive or leasing programs could be negotiated with landholders where property owners restore their riparian vegetation in exchange for compensation which recognises any loss in productivity. Developing programs such as this is likely to result in a win-win for all involved - it simply requires better planning and more targeted funding for catchment management in South East Queenland. We hope this is what the recently announced River Improvement Trust can help deliver.

Some more related blogs:

2014 SEQ Healthy Waterways Report Card is released (October 2014)
River Basin Management Society in SEQ (November 2014)
Smales Park bank stabilisation works (January 2015)