FAQs
About the flood study
- probabilistic flood mapping (including levels, depths, velocities) to be able to share with the community
- identification of flood planning areas
- emergency management and community awareness information
- an understanding of future flood scenarios incorporating climate change and development
- Data Collection - Gathering both new and existing data including on historic flood information.
- Flood Study – identifying flood behaviour including the areas previously flooded, water depth, hazard and the likelihood of flooding within the area.
- Floodplain Risk Management Study – Understanding how flooding affects the community and identifies strategies to minimise impacts.
- Floodplain Risk Management Plan -Proposing flood mitigation options to be put into place to manage flood risk across the catchment. These options are adopted council
- Plan Implementation – Implementing strategies, such as infrastructure upgrades, mitigation works, drainage upgrades, development controls, community awareness and emergency response arrangements.
- New data on rainfall or ground topography
- Additional data from recent floods which is used to fine-tune the models.
- Updated flood modelling guidance and science
- Advancements in flood modelling techniques and computer technology
- New development or flood mitigation works in the catchment area
- the cost of claims generated by the series of major disasters (including storms, flooding and bush fire)
- Australian insurers paying more for reinsurance (insurance that insurers take out to cover major events) because of these disasters
- changes in understanding where and when floods will occur and how much it costs to fix damage.
What is a flood study?
A flood study is a comprehensive technical investigation of flood behaviour within a specific study area. It plays a crucial role in floodplain management by helping understand flood risk to inform decisions related to development, infrastructure and safety. The study takes into consideration local flood history, and uses advanced hydrologic and hydraulic models to understand flood risk.
Key outcomes of a flood study include:
What is the Floodplain Management Process?
The process is guided by the NSW State Government’s Flood Prone Land Policy and follows a structured approach. The NSW Government flood risk management manual sets a framework and process for Council's to follow to assist with managing flood prone land.
This process involves;
The project includes the data collection and flood study components of the process.
Who will be undertaking the study?
The City engaged specialist flood consultants JB Pacific to undertake the study. They will collaborate with the City, Department of Climate Change, Energy, the Environment and Water (DCCEEW), and the State Emergency Service (SES) to undertake the study.
What areas are included in the flood study?
The flood study covers the localities of Moonee Beach, Sapphire Beach and the parts of Emerald Beach in the Moonee Creek catchment.
Have there been previous studies in these areas?
A previous flood study was completed in 1998 by Paterson Consultants.
Will the flood mapping change?
Yes, flood mapping may be updated as part of this study. The flood models used to predict flood behaviour could change due to several factors including:
How is the flood study information used?
Flood studies help us understand how floods behave, the hazards they pose, and the risks involved. This will allow both the City and other agencies to plan and manage these risks based on the best possible information.
They will be used in land use planning, emergency management planning, and the implementation of planning controls in relation to flooding.
Flood information will also appear on Section 10.7 planning certificates to inform current and future owners know that a property may be subject to flood related development controls.
Will the updated flood mapping impact insurance premiums?
Insurers use data from a variety of sources including historical flood measurements, Federal, State and Local government studies, the Insurance Council of Australia’s (ICA) National Flood Information Database and through their own research.
Insurance companies use these sources of data to make their own assessment of risk. In essence, different companies will assess the risk in different ways and the City does not control what flood data insurers choose to use or how they use it.
Over the past few years, a number of factors have combined to raise the price of flood cover and insurance more generally. These include:
The Insurance Council of Australia advised Council that people should shop around if they are dissatisfied with the cost or coverage of their flood insurance. Residents are also advised to look carefully at what they are covered for, rather than just basing their decision on the price.
What is the meaning of Annual Exceedance Probability (AEP)?
AEP represents the likelihood of a certain size flood happening in any given year, usually expressed as a percentage.
A 1% AEP flood has a one per cent or 1 in 100 chance of occurring or being exceeded in any year.
Design floods are hypothetical floods used to understand flood risk and for planning and floodplain management investigations.
Example: Over an 80-year life span, there’s just over a 50% chance of experiencing a 1% AEP flood – like flipping a coin. The table below indicates the chance of experiencing a certain sized AEP flood over an 80 year period.
What is the flood planning level and area?
Flood Planning Level: a height used to set floor levels for property development in flood prone areas. For most developments, this is the 1% Annual Exceedance Probability flood level plus 0.5 metres of freeboard. This level may be higher for vulnerable land uses (e.g. hospitals or schools).
Flood planning area: the land below the Flood Planning Level where flood related development controls apply.