MBRC Planning Scheme - Flood hazard overlay
Our city has a history of flooding because of our terrain and proximity to waterways. It is important to address the risks and hazards that flooding presents when assessing development.
A Flood hazard overlay map indicates areas subject to flood hazards or other impacts and their possible extent. It also identifies areas of the city subject to riverine flooding, up to the rarest of flooding events that can be modelled. This is also known as the Probable Maximum Flood (PMF). Any development proposed within this mapped area triggers an assessment against the Flood hazard overlay code.
Under state government requirements, planning schemes must identify areas at risk of flooding. This helps determine when the Flood hazard overlay code applies. It doesn’t reflect changes to the landscape from new development, or provide information on:
- current flood conditions
- flood immunity.
Flood hazard overlay code
The Flood hazard overlay code categorises areas into three planning areas:
- High risk flood hazard area
- Medium risk flood hazard area
- Balance flood planning area.
It also outlines planning, building, and engineering requirements for developing in these areas. The code mitigates flood risks by limiting the exposure of land uses in medium and high flood risk hazard areas. It also outlines assessment benchmarks to mitigate flood risks to future users of the site, as well as emergency managers.
To understand the flood-related requirements of our planning scheme for your property, request a flood check development report.
How Flood hazard overlay mapping affects properties
If your property is identified in the Flood hazard overlay mapping and you wish to develop it, the overlay may affect your plans.
Under state government regulations, any development in these areas is subject to planning and building controls and safety requirements. This helps protect property owners and residents by ensuring new development is resilient to flooding.
Where possible, you should mitigate risks by locating structures and uses in the least flood-affected areas of your site. Certain uses and buildings can be exposed to certain levels of flood risk where engineering standards have been met.
Do not use Flood hazard overlay mapping to understand your property’s current flood risk or for insurance purposes. Learn more about using Council information to inform flood insurance quotes.
Flood planning areas
A flood planning area is a designated area where development is subject to specific flood-related controls.
These areas must be identified in the planning scheme. They are locations that can flood because of heavy rainfall, even if the land does not flood frequently.
Information on flood planning areas is for planning purposes only. The map will not be updated to identify any changes to the floodplain from ongoing works such as new development and flood mitigation. Changes to this area may occur following a review or update to the city's flood risks via a flood risk assessment.
High and medium flood risk areas
Council prepares flood estimates using computer-based models. The models calculate where water will flow when it escapes from a watercourse or low point. Council's flood hazard overlay maps high and medium-risk areas by considering the depth and velocity of floodwater. It also considers the frequency of inundation.
In some cases, areas may be classified as high-risk if the water depth is significant. This is even if the water moves slowly, such as in a canal or waterway. Areas with fast-flowing water may be high-risk even if the water is shallow.
High and medium risk areas are based on flood model outputs from 2014.
Balance flood planning area
The balance flood planning area includes all flood-prone land outside high and medium-risk areas considered to have a low to negligible risk of flood hazard.
Drainage investigation area
A property may be in a Drainage investigation area without an adopted Drainage Master Plan as identified in the planning scheme policy(PDF, 134MB). These property owners can have a Drainage Master Plan prepared as part of a development application for Council approval.
Learn more about drainage investigation areas.
Excavation and filling near wetlands and in flood hazard areas
Before building or developing, be aware of regulations for excavating and filling near wetlands and in flood hazard areas.
Unapproved or non-compliant excavation and filling activities can impact our waterways. These actions can:
- change overland flow paths
- degrade public infrastructure
- increase the risk of flooding for neighbouring properties.
To manage these risks and receive approval before undertaking any activity, contact Council.
Your property and wetland areas
See if your property is within a wetland area with my property look up. If there is no reference to the riparian and wetland setbacks overlay in the property report, then it does not apply to your property.
For more information, you can also use Council's:
Flood information that is separate to the planning scheme
Outside of a major scheme amendment, the planning scheme flood hazard overlay cannot be updated with Council's latest flood information.
Find the most up-to-date flood information for your property. This information is separate from the planning scheme, allowing it to be updated as new information becomes available.
Frequently asked questions
My home is at the top of a hill, why am I affected?
Council uses overland flow path mapping to identify areas impacted by overland flow. Overland flow is generally caused by run-off from short and intense rainfall.
Planning schemes must identify an area where overland flow controls apply. These controls protect new development from potential damage from inundation. It also helps manage the risk of overland flow paths being impeded or redirected onto surrounding properties.
If there is significant rain at the top of a hill, the runoff will run downhill over the ground surface and will concentrate in low-lying gullies, channels, roads and surface depressions.
Why is my neighbour's property mapped differently?
Council prepares flood estimates using a combination of historical data and computer-based models that show where water will flow when it escapes from a watercourse or low point. Even a small variation in topography (height of the land) compared to a neighbour may result in a property being affected by flooding.
My property has stormwater drainage, why is it mapped?
Stormwater drains and pipes are designed to handle more frequent, smaller flood events. In larger rainfall and storm tide events, stormwater infrastructure will function as designed but excess water may cause flooding.
Why can't I fill my property?
Filling your property can impact drainage and increase the risk of flooding for neighbouring properties. Some filling is permitted in coastal areas where the floodplain is largest. Any filling that may be allowed must follow a prepared design and should consider any impacts on neighbours.
Further details can be found in the flood hazard and coastal hazard - Storm tide inundation information sheets.