Tweed Heads South levee and drainage study

Thank you for your input. Submissions closed on Sunday 6 August 2023. We're now developing a new, detailed flood model of the river and stormwater drainage system across Tweed Heads South and Banora Point. Once the model is developed it will be calibrated against historic flood information which includes flood marks surveyed by Council as well as the survey responses you provided.

Tweed Shire Council, with support from the Department of Planning and Environment (DPE), has engaged flood specialists Catchment Simulation Solutions to prepare a detailed levee and drainage study for Tweed Heads South and Banora Point.

The study follows on from significant flooding in March 2017 as well as February and March 2022. These events caused widespread and devastating impacts on our community, property, business, industry and public infrastructure, including Tweed Heads South and Banora Point.

The current study will build upon the Tweed Valley Floodplain Risk Management Study that was completed in 2014. It will provide a detailed understanding of drainage behaviour behind the levee as well as the potential consequences of levee overtopping from riverine flooding, overland (i.e. flash) flooding, storm surge or a combination of both. This, in turn, will form the basis for investigating options that could be implemented to better manage the flood risk.

Community input has an important role in the study. It helps us understand your personal experiences from past flood events as well as potential flood risk management options.

Submissions for the first stage of community consultation closed on Sunday 6 August. This focused on collecting as much historical flood information as possible to help calibrate our computer flood models. It also allowed the community to provide initial feedback on flood risk management options that will be investigated in detail later in the project.

Further community consultation will be conducted once a preliminary list of flood mitigation measures has been developed and again when the levee and overtopping study report has been drafted.

Why another study is needed

The Tweed Valley Floodplain Risk Management Study was prepared in 2014. It provided a regional understanding of the flood risk across the Tweed Valley along with recommendations on potential flood risk management measures to manage that flood risk. This previous study also acknowledged that it was a ‘catchment scale’ investigation and did not reliably reflect fine-scale details such as the Tweed Heads South urban area. Therefore, this study also recommended that more detailed, local drainage studies be completed to better understand the flood risk.

The Tweed Valley Floodplain Risk Management Study ultimately recommended the following measures and studies for further investigation:

1. Commission local drainage studies - High priority
2. Commission levee overtopping study - Medium priority
3. Raise Tweed Heads South levee - Medium priority
4. Extend Tweed Heads South levee to Philip Parade - Medium priority

The current project will directly address items 1 and 2 and will be a key step in moving towards the implementation of items 3 and 4.

The different flood types affecting Tweed Heads South

The Tweed Heads South study area is shown in the image below. It covers a total area of 15 km² and can be impacted by 3 different types of flooding:

• riverine flooding is caused when the flow of water bursts the banks of creeks or rivers
• storm surge flooding is an abnormal rise in seawater level due to a storm
• overland stormwater or flash flooding is generated by rainfall running off towards the drainage or creek system.

Why it's important to hear from you

Consultation with the community will be completed in 3 stages:

• Stage 1 (July/August 2023): An information flyer was distributed to the Tweed Heads South study area which called on past and present residents of the Tweed Heads South, Banora Point and surrounding areas to share their flooding experiences. Community input was invaluable in understanding flooding ‘trouble spots’. It also provided the opportunity for the community to provide initial feedback on mitigation options you would like to see implemented. The survey closed on Sunday 6 August 2023.
• Stage 2 (March 2024): We will complete further community consultation once a preliminary list of mitigation options has been prepared. It will allow you to provide feedback on each option which will be a key input into determining which options are implemented.
• Stage 3 (August 2024): We will conduct the final stage of community consultation once a draft report is prepared. It will allow you to review the outcomes of all stages of the project including what options are being recommended to better manage the flood risk. We will take your feedback into consideration before submitting the report to Council for adoption.

If you have any questions or would like to provide additional information or photos, please contact:

Leon McLean
Engineer – Flood and Stormwater
Email: tsc@tweed.nsw.gov.au
Phone: 02 6670 2400