What is flooding
Storms and floods are a natural hazard. Climate change, urban development, and aging infrastructures can all contribute to an increased flood risk. It is important to note that flooding cannot be completely prevented, particularly in older, well-established urban areas.
Types of flooding
Stormwater flooding: Stormwater flooding occurs when heavy rainfall exceeds the capacity of the drainage (pits and pipe) system, causing water to overflow onto streets and surrounding areas. It is most common in built-up urban areas.
Waterway flooding: Waterway flooding happens when rivers and creeks overflow due to heavy or prolonged rain. This is most common in areas near rivers, creeks, and floodplains, where excess water has nowhere to go.
Coastal flooding: Coastal flooding occurs when high tides, storms, or rising sea levels push seawater inland, affecting beaches, coastal towns, and low-lying shorelines
Flood management responsibilities
Responsibility for flood management is shared between Melbourne Water, councils, State Emergency Services and other key partners.
Melbourne Water is the floodplain management authority for Port Philip and Westernport region. Melbourne Water is responsible for:
- Regional drainage (large drains servicing catchments larger than 60 hectars and creeks )
- Floodplain and waterway management
Casey Council is responsible for the management and maintenance of the local stormwater drainage system that services catchment less than 60 hectars. Council is also responsible for applying building and planning controls on developments to address and mitigate flooding risk.
The Department of Transport and Planning is responsible for some stormwater drainage systems on arterial roads and freeways.
Property owners are responsible for the drains and pipes that collect stormwater on their own property, including the pipes that run under the footpath and nature strip. These pipes and pits are part of the private stormwater drainage system.
The State Emergency Services, Melbourne Water, Council and other government bodies are also involved in emergency response and planning for floods, including community education.
You can take the following steps to be emergency prepared and up-to-date with incidents and warnings:
- visit VICSES for local flood guides and a Municipal Flood Emergency Plan.
- download the VicEmergency app or visit www.emergency.vic.gov.au
Managing flood risk in the City of Casey
The City of Casey has many low-lying areas which are naturally prone to flooding. With extreme rain events becoming more common and denser developments, the risk of flooding is increasing.
While we can’t prevent all flooding, Council is working to reduce the risk of floods for our community by:
- upgrading drainage infrastructure where practicable
- maintaining Council’s drainage assets
- implementing non-structural solutions such as land use planning controls, flood warning systems and community education.
Flood mapping
Under Regulation 148 of the Building Regulations 2018, Council is required to prepare mapping for areas under its control that are liable to flood. Melbourne Water is also working with Councils across Victorian to update flood maps for the Greater Melbourne area.
The City of Casey is working closely with Melbourne Water to ensure Council has the most up-to-date flood hazard information (flood maps). These maps show areas that may be affected during rare but significant rainfall events, known as 1% Annual Exceedance Probability (AEP) storms. 1% AEP means there is a 1% chance of such an event (e.g. an infrequent high-intensity storm), occurring in any given year.
These events are not cyclical. They might happen more than once in a given year, or there might be several years without such an event occurring.
How flood maps are used
Flood mapping is a vital tool for managing and reducing flood risks. Flood modelling is helping to predict where water would spread and how deep it would in the event of heavy rain or waterways overflowing.
This information helps governments, the private sector and community organisations with:
- establishing and enforcing zoning, land-use policies, and building standards
- planning infrastructure and transport networks
- supporting flood warning systems, evacuation planning, and emergency management
- guiding long-term urban growth and resilience strategies
- identify whether a property is at risk of flooding and provide advice to property owners
- planning flood mitigation projects.
For individuals and communities, flood maps provide valuable insights into local risks and help people to plan and prepare. This might include identifying safe evacuation routes or locating suitable emergency shelters.
Additional Information
To request specific flood information for your property, please apply to obtain a Property Information Certificate from Council.
Before a building permit, you may need a flooding application if the land is prone to flooding.
Before lodging your application, please discuss with the private building surveyor engaged for the issue of the building permit, as exemptions may apply.