Carnarvon Floodplain Management Working Group report

The Working Group’s report details key recommendations to resolve current issues and be better prepared for future events which includes five critical areas:

• a governance structure to promote a coordinated and long-term strategic approach to floodplain management
• flood planning and mapping to increase understanding 
• reducing impacts through waterways management 
• reducing loss through improved soil conservation and land management practices 
• improving waste management. 

Background

The Working Group was established by the state government to assist the horticulture industry recover and reduce future impacts following the flooding of the lower Gascoyne River in 2021. The Working Group comprises representatives from key stakeholder groups: 

• Department of Primary Industries and Regional Development (DPIRD)
• Department of Water and Environmental Regulation (DWER)
• Commissioner of Soil and Land Conservation
• Fire and Emergency Services
• Department of Planning, Lands and Heritage
• Gascoyne Development Commission
• Shire of Carnarvon
• Horticulture industry members and representatives from Carnarvon Growers Association.

Periodic flooding of the lower Gascoyne River floodplain at Carnarvon is a natural event. The flooding results from cyclonic and thunderstorm activity, with the risk period generally from November to May, associated with the wet season in the north of Western Australia. The Carnarvon horticultural area has suffered considerable damage following flooding of the Gascoyne River in 1960, 1961, 1974, 1980, 1995, 2000, 2009, 2010/11 and 2021. 

Progress update 

Recommendations are being actioned by: 

• the Working Group members
• Shire of Carnarvon’s Flood Preparedness Project, which received funding in 2022 under the Australian Government’s Preparing Australian Communities Program.

The Shire of Carnarvon project funding was obtained for flood planning, mapping and waterways management. A Digital Elevation Model has been developed through comprehensive surveys of the river and floodplain including Light Detection and Ranging (LiDAR) flights.  

Next steps

The next steps are to develop flood modelling of the area, including possible flood mitigation options, and the final report.

The floodways management report has been drafted and will include recommendations for the project to action natural upgrades to the riverbanks and floodways.

The Working Group have completed the majority of the recommendations on governance and improved waste management. DPIRD is working with growers to inform them on improved soil conservation and land management practices.