Flooding.
What is Flood Risk?
Flood planning is an important part of the development process in New South Wales. Whether you’re lodging a Development Application (DA) or a Complying Development Certificate (CDC), councils require clear evidence that your proposal is safe, practical, and won’t worsen flooding elsewhere. Our consultancy specialises in preparing Flood Impact and Risk Assessment Reports that meet these requirements - helping property owners, architects, and developers gain approval with confidence.
Did you know our Director helped write the most recent stormwater management and flood risk policies for Sutherland Shire Council?
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Stormwater is short-term surface runoff easily managed by gutters, pipes and drains. Flooding occurs when flow exceeds the capacity of these stormwater systems’ capacity. Stormwater is frequent but minor; floods are rarer but larger and can cause significant risk to life and property.
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Flood-prone land includes any area that may be inundated during a flood event. The most common reference point is the 1 % Annual Exceedance Probability (AEP) flood, which forms the Flood Planning Area (FPA). Extreme events are measured against the Probable Maximum Flood (PMF) to plan for safe evacuation and emergency access.
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Most councils map flood-prone land and note it on Section 10.7 Planning Certificates. If your property falls within a mapped area, you’ll likely need a Flood Impact and Risk Assessment Report before development approval. We can quickly review your site and confirm what type of report is required.
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You may be wondering why your property is classified as Flood Prone when it has never flooded before (No matter how long you have lived there).
Flood risk management is a game of statistics - where rainfall records and historical flood data are used to estimate if and how often different sized flood events could occur.A better way to think of the “1-in-100 year” flood event is that this has a 1% chance of occurring in any year. Hence the new name 1% AEP.
Statistically speaking, within the average 80-year lifetime, a person has a 55% chance of witnessing a 1% AEP flood event and less than a 0.1% chance of witnessing the PMF.
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Yes, with the right advice and design. Measures may include raising floor levels, using flood-resistant materials, or allowing water to pass beneath structures. Our reports demonstrate how a proposal meets these safety and performance requirements.
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Flood planning protects people, property, and the environment. Every development must demonstrate that it can remain safe during flooding events and won’t increase flood risk for neighbours. Councils are legally required under NSW planning rules to use the best available information and ensure that new buildings and access ways are safe and properly designed.
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Depending on your site’s risk, councils may request:
A Flood Impact and Risk Assessment (FIRA),
A Flood Study or Hydraulic Model, and/or
A Flood Emergency Response Plan.
Our consultancy prepares all these documents across NSW, ensuring they align with current policy and are ready for lodgement.
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As early as possible - typically before lodging your DA or CDC. We regularly work with homeowners, designers, and planners to prepare reports that satisfy council conditions the first time.
Council controls vary depending on whether a lot or development is known to be at Low, Medium or High Risk of flooding. Early advice helps set floor levels, design drainage, and avoid costly redesigns.
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Modern flood studies consider higher rainfall intensity, sea-level rise, and changing catchments. Our assessments apply the latest methodology so your design remains compliant and resilient long-term.
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Simply send us your site address, plans, or council request letter via the button below or the Contact Us request form.
We’ll confirm whether a flood report is required and provide a fixed-fee proposal. Reports are technically sound, and ready for immediate submission with your DA or CDC.
