Flood study (council)
A council flood study maps flood behaviour, sets the Flood Planning Level, defines flood risk precincts, and underpins DCP flood rules for residential approvals.
Ask Chalkline about this →A flood study is the engineering investigation commissioned by a local council (or the state floodplain authority) that maps the flood behaviour at a specific catchment or sub-catchment, sets the Flood Planning Level (FPL) at each property, defines flood risk precincts (commonly Low / Medium / High), and feeds the council’s DCP flood chapter that residential builders read at DA stage. A council flood study is the upstream document that gives meaning to every “flood-prone” classification on a Section 10.7 certificate or planning information request (verified 2026-05-16).
What a typical flood study contains:
- Hydrologic modelling of the catchment (rainfall, runoff, river or creek flow).
- Hydraulic modelling of how flood waters move through the floodplain.
- Design flood event mapping (commonly the 1% AEP flood event = “100-year flood”, plus the larger Probable Maximum Flood).
- Flood Planning Level (FPL) for each property: the level above which habitable floor level must be set.
- Flow velocity and depth maps identifying high-hazard zones.
- Flood risk precincts: Low Flood Risk, Medium Flood Risk, High Flood Risk, with different controls for each.
How a builder uses the flood study at DA stage:
- Check the council’s flood study report before designing the floor levels. It is usually a public document held by council and downloadable from the council website.
- Read the council’s DCP flood chapter for the controls that apply at each risk precinct (habitable floor level relative to FPL, restrictions on dwellings in High risk, fill controls, evacuation requirements).
- Engage a hydraulic engineer to prepare the project’s Flood Management Report against the flood study and DCP controls.
- Section 10.7(2) certificate flags the property as flood-affected and refers the user back to the flood study and DCP.
How current is the flood study?
Flood studies have varying ages: some councils have studies that are 5 to 20 years old, others have very recent updates that reflect Australian Rainfall and Runoff 2019 methodology and post-2022 flood data. The age matters: pre-ARR-2019 studies may now under-predict flood events under current climate science, and councils sometimes apply a “freeboard” adjustment to older study FPLs.
Where flood studies fit in the wider system:
| Document | Source | Function |
|---|---|---|
| Flood study (this) | Council, commissioned every 10-20 years | Catchment-scale mapping and FPL setting |
| DCP flood chapter | Council planning policy | Translates flood study into development controls |
| Section 10.7 certificate | Council, per property | Discloses flood classification on a specific property |
| Flood Management Report | Hydraulic engineer, per project | Demonstrates project compliance against flood study + DCP |
Also known as: floodplain risk management study; flood mapping study; council flood map.
Category: Approvals.
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Last updated: 2026-05-16. Verified: 2026-05-16. Quarterly review for currency.