The community information session is an opportunity for you to:

Learn about the Newstead Flood Study.

• View updated flood mapping following community consultation.
• Provide feedback on draft flood mitigation options.
• Ask questions of Council staff, Water Technology and the North Central Catchment Management Authority.

We’re interested in your ideas on how we can collectively reduce the impact of floods in Newstead.

Newstead has a history of flooding with events in 2000, 2010, 2011, 2016 and 2022.

The Newstead Flood Study and Mitigation Strategy is a long-term project that will help us improve how we prepare for and respond to floods in the future.

It will provide recommendations on flood mitigation measures for the town, as well as inform engineering designs for an updated flood levee

There is currently an earthen levee that provides Newstead with a level or protection against flooding.

However:

• The characteristics of the levee are unknown.
• There is no formal management arrangement.
• There are no automated local warning systems for the complex flood scenarios.

As a result, we are undertaking a comprehensive assessment of flood risks within the Newstead catchment area (marked in the map below).

We’re doing this to better understand the potential impacts of flooding, identify areas at risk, and develop best practice strategies to manage and mitigate these risks.

The study is being conducted by expert consultants Water Technology.

They are working closely with Council, North Central Catchment Management Authority, the Project Steering Committee and the Newstead community.

The Project Steering Committee brings a broad range of stakeholders, knowledge and experts into the project.

This includes funding partners as well as representatives from North Central Catchment Management Authority, Bureau of Meteorology, Coliban Water, Department of Energy Environment and Climate Action, Department of Transport and Planning, Dja Dja Wurrung, Goulburn Murray Water, Victoria Police, Victorian State Emergency Service, Mount Alexander Shire Councillors, and community representatives.

The project is funded by the Victorian Government and the Australian Government’s Disaster Ready Fund (DRF).

Council is project managing the study with technical support from North Central Catchment Management Authority.

A detailed design phase that will follow the study is funded by Council and the Australian Government’s Disaster Ready Fund. Funding for construction work is not yet available.

Council plans to advocate for this through State and Federal grants with potential Council contribution.

Deliverables for the study include:

• Calibrated hydrologic and hydraulic computer models which will provide detailed flood information, including flood map extents, depths, heights and velocities for a range of flood events of different sizes and Annual Exceedance Probabilities (AEP). The models are to factor in likely climate change aspects.
• Flood intelligence to be incorporated into the Municipal Flood Emergency Plan including roads impacted and buildings that may experience above-floor flooding.
• Flood mapping to be incorporated into the Mount Alexander Planning Scheme updating the flood-related planning controls.
• Recommendations regarding flood mitigation options including an understanding of the current level of protection offered by the Newstead Township Levee and identification of works to upgrade this infrastructure.
• A comprehensive final report that outlines the methodology, findings, and recommendations.
• Update to flood intelligence products including pre-prepared maps, impacted buildings and impacted transport routes.

No, works on the floodgate were completed in March 2025 and were independent of this project.

The Newstead Flood Study results will also inform the development of any necessary flood-related planning tools, that may include a planning scheme amendment.

If specific properties are identified as likely to be affected by flooding in the future, those properties may be impacted by new flood-related planning controls.

Any proposed flood-related planning controls, including planning scheme amendments, will guide current and future property owners and developers to consider flood risk while developing properties, which may include the need for planning permits.

State Planning Policy requires that we minimise the impact of natural hazards (such as flood) and adapt to the impacts of climate change through risk-based planning.

The Newstead Flood Study uses the latest available climate change science to understand flood risk into the future.

We’re consulting the community in three stages:

Stage one – Completed in June 2024

We introduced the project, shared historical data and took input from the community.

Hardcopy and online data maps were presented at a community consultation session to help with discussion and knowledge reporting.

Community input data was collated to inform stage two.

Stage two – Mid-2025

Mapping and draft mitigation options, study results and potential options will be shared with the community.

Draft hardcopy and online maps will be available to prompt discussion and input.

Stage three – Late-2025

We will present and discuss the final results with the community.

Phase 1

Collection and review of historical data and collection of community knowledge.

Surveyors in the area collect ground and floor levels.

Phase 2

All data is fed into hydrologic and hydraulic computer modelling. The modelling goes through testing and calibration to improve accuracy and ensure it is representative of actual events. Draft modelling is produced to reflect the movement of water over the catchment in different scenarios, depending on the existing state of the landscape and where, how much and how quickly rain occurs.

The draft modelling also includes projections for climate change, or the 1% Annual Exceedance Probability (AEP) flood. The AEP means there is a 1% chance of a flood occurring, or being exceeded, in any one year. It is the Victorian Government standard to regulate and protect new developments through state planning and building systems.

Phase 3

After the draft modelling is confirmed, damage assessments for individual locations are run and mapped. Risk management options are then assessed with consideration of their effects and feasibility. Recommendations will be made in a final report in late 2025.

1% AEP modelling

1% Annual Exceedance Probability (AEP) means there is a 1 out of 100 chance that a really big flood could happen in any year. It’s like picking a number from a hat with 100 numbers—if you pick number 1, that’s the flood!

Appendix A shows the 1% AEP flood developed during the Newstead Flood Study in accordance with historical information such as newspaper accounts and recorded peak flood levels, physical conditions such as ground contour information and aerial photography, computer modelling and local knowledge gathered through community consultation.

1% AEP Climate Change modelling

Modelling was also undertaken with consideration for increased rainfall intensity associated with climate change. *SSP3 year 2100 scenario was assessed based on recommendations from NCCMA. The 1% AEP Climate Change scenario shown in the flood map, Appendix B Council will use to update the planning scheme once the Flood Study has been completed.

State Planning Policy requires that we minimise the impact of natural hazards – such as flood – and adapt to the impacts of climate change through risk-based planning. The Newstead Flood Study uses the latest available climate change science to understand flood risk into the future.

*SSP3, or Shared Socioeconomic Pathway 3, is one of five global scenarios used in climate modelling to explore how different social, economic, and political trends might influence greenhouse gas emissions and climate change impacts through the 21st century

1% AEP Mitigation modelling – Clearance of vegetation in area around Pyrenees Highway bridge

Appendix C modelling shows the flooding at Newstead if the vegetation is reduced directly upstream and downstream of the Pyrenees Highway Bridge.

1% AEP Mitigation modelling – Raising the Newstead Levee

Appendix D modelling shows the flood behaviour at Newstead if the current levee alignment is raised above the 1% AEP flood level, but the levee is not extended.