Drainage and Flood Protection
The drainage system carries rainwater from roofs, roads and buildings through gutters, drains and channels and discharges it into rivers and creeks where it eventually flows to the bays. The drainage system must be kept in good condition at all times to provide essential flood protection.
- Our role
- The role of local councils
- Flood protection
- Flood mitigation
- Flood warning system
- Keeping our assets in good condition
- Flood management and drainage strategy
Our role
We are responsible for managing the regional drainage system for the Port Phillip and Westernport region - that's more than 1200 kilometres of drains. This involves providing a safe and effective system for transferring stormwater run-off through a network of major underground drains and overland floodways (a channel for an overflow of water caused by flooding) to rivers and creeks and the bays.
We have a program in place to regularly monitor the condition of the drainage system to ensure it remains in good condition.
The role of local councils
Councils are responsible for local drains, road networks and street drainage which all feed into the regional drains, rivers and creeks.
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Flood protection
We manage run-off from rural and urban areas to:
- provide communities with a safe level of flood protection
- ensure urban development does not adversely affect floodplains (the land surrounding rivers and creeks that can sometimes experience flooding).
Flood protection is achieved by:
- limiting development in floodplains and overland flow paths to preserve these areas for storage and conveyance of floodwaters
- ensuring new urban areas incorporate stormwater treatment and accommodate overland flows of floodwaters without threatening property and public safety
- building and operating infrastructure such as drains, levees, retarding basins and wetlands to contain, convey or treat stormwater
- operating a flood warning network on major rivers and creeks
- increasing awareness of flooding risks through education programs
- encouraging water sensitive urban design techniques to be used in new urban developments
- working with councils to introduce planning controls to identify land subject to overland flows
- working with councils and the State Emergency Service to ensure emergency response plans are in place to minimise disruption in the event of a flood.
Programs for flood protection include:
- Flood mitigation
- Flood-warning system
- Keeping our assets in good condition
- Flood management and drainage strategy
- Land development controls
- Community education and awareness programs.
Flood mitigation
We have a number of strategies to reduce the number of properties and areas that are vulnerable to extreme or intolerable levels of flood risk.:
New infrastructure is built to better protect properties. However this is expensive and disruptive to communities in existing urban areas and needs to be carefully considered.
The cost of flood damage in existing urban areas is assessed to work out the potential benefit of expenditure on flood mitigation projects. There are two types of costs of flood damage that are assessed:
- direct damage such as damage to building, floor coverings and possessions; and
- indirect damage such as disruption to business, trauma and loss of income.
When vulnerable properties are redeveloped, the floor levels of new or replacement dwellings are set above the level of localised flooding to improve protection.
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Flood warning system
We operate an on-line, 24-hour a day rainfall and river level monitoring network.
The Bureau of Meteorology is responsible for issuing flood warnings throughout Australia. We provide the Bureau with predicted times and areas of flood, so that formal warnings can be issued to responsible agencies and the community.
Our flood warning system relates to the following rivers and creeks:
- Yarra River
- Maribyrnong River
- Bunyip River
- Dandenong Creek
- Diamond Creek
- Plenty River
- Kororoit Creek
- Merri Creek
Early predictions and warnings can be made for these rivers and creeks because of their size. Early warning allows an effective emergency response. Locally determined flood levels are set to classify flows as minor, moderate or major. Flood effects above each height reflect the category of flooding. Councils that have flooding issues are working with us to develop and review their Municipal Emergency Management Plans so that information from flood studies is included.
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Keeping our assets in good condition
Built assets require effective asset management throughout their life cycles, so they are fully operational and meet public health, safety and environmental requirements.
We make sure that our built assets are well maintained and perform according to their design requirements. This means flood damage as a result of system deterioration or malfunction is avoided and the number of properties vulnerable to flooding does not increase.
Flood management and drainage strategy
This strategy outlines key flood management objectives and the actions that will be undertaken to achieve each objective. It also guides our priorities and expenditure.
Important objectives include:
- completing our knowledge base on how best to manage floods
- planning for potential long-term pressures on existing drainage systems
- developing an agreement approach to managing existing regional flooding problems
- enhancing community education, flood awareness and preparation
- agreeing on responsibilities and improving collaboration between flood management agencies.
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