Flooding and its impacts

Types of flooding

Flooding can happen in different ways depending on where you live.

Stormwater flooding

When heavy rain exceeds the capacity of the drainage system, water can spill onto the streets. Stormwater flooding is common in built-up areas, and can happen quickly without much notice.

Waterway flooding

Heavy or prolonged rain can cause rivers and creeks to overflow into neighbouring areas. Floodwaters can rise slowly and last for days, cutting off communities.

Coastal flooding

High tides and storms can combine to push seawater inland, affecting beaches and coastal towns. As sea levels continue to rise, some low-lying areas may regularly flood.

Impacts of flooding

Floods can have wide-ranging and long-term consequences for the community. The impacts are estimated to cost $735 million a year, and include:

• damage to homes and infrastructure
• road closures, traffic jams and disruption to services
• social and personal costs, such as loss of possessions, stress and illness. 

Flooding can also harm the environment, eroding shorelines and carrying litter into rivers and creeks. It can take time for them to recover, affecting the people and businesses who rely on them.

You can limit the damage by taking simple actions in advance to prepare for flooding.

Impacts by flood type

Stormwater flooding

Alex lives in South Melbourne, where stormwater floods are common after heavy rain. During storms, they know to avoid driving near the Montague Street and York Street bridges, because cars often get stuck in the floodwater under the bridges. The floodwater can appear quickly and with little notice.

Waterway flooding

Carolina lives in Warrandyte, a suburb along the Yarra River that is prone to flooding after days of heavy rain. She keeps track of river levels during storms and knows that some local roads, like Yarra Street, can become blocked. When flood warnings are issued, she moves valuables to higher shelves and checks emergency updates in case she needs to leave early before roads are cut off.

Coastal flooding

Tom lives in Seaholme. When a storm occurs during a very high tide and southerly winds, sea water can come over the wall next to the beach. He follows weather updates, especially in winter when strong winds and storm surges are more common. When heavy rain and high tides are predicted, he moves his car to higher ground and checks that his drains on his property are clear. If severe weather is expected, he also secures loose items in his yard and stays alert for emergency warnings.

Impacts by property type

Apartments and units

What can happen	How to prepare
Flooding in underground car parks can damage vehicles and belongings.	Keep valuables off the ground. Temporarily move vehicles to higher ground.
Water leaks can cause mould and structural issues.	Check for leaks and address damp spots early.
Electrical hazards and pests are common after floods.	Maintain drains and gutters and seal entry points to prevent pests entering.

Townhouses and semi-detached homes

What can happen	How to prepare
Fast-moving water can carry debris, putting your safety at risk.	Keep outdoor areas clear.
Water can seep through walls, weakening structures and causing mould.	Seal cracks and check for moisture buildup.
Street flooding may cut off access by road or footpath.	Have an emergency plan for road closures. Temporarily move vehicles to higher ground.

Freestanding homes

What can happen	How to prepare
Floodwater can reach power points and appliances, posing safety risks.	Raise power points and install flood barriers.
Waterlogged foundations can cause structural damage.	Inspect and reinforce foundations before and after storms.
Blocked roads and flooded driveways can leave you stranded.	Keep emergency supplies on hand and plan alternative transport.
Garages and carports located in lower areas may flood more easily.	Temporarily move vehicles to higher ground. Keep valuables in garages and carports off the ground.

Rural properties and farms

What can happen	How to prepare
Standing water can impact land available for crops and livestock.	Improve drainage and move animals to higher ground.
Floodwaters can wash away fences and roads may be cut off for long periods of time.	Secure fences and plan alternative routes. Stockpile essential supplies.
Crops and machinery can be lost or damaged.	Store damaged. Store equipment properly and consider insurance.
Power outages and supply shortages are common.	Set up a generator and stockpile essential supplies.

Managing flood risk

We can’t completely eliminate flooding, but we can minimise the risk and impacts.

Drains, retarding basins and other flood mitigation infrastructure can reduce the risk of flooding. But they’re not always the most practical or cost-effective option.

Effective flood mitigation uses multiple strategies, such as: 

• community awareness to help people understand and prepare for floods  
• planning controls to manage houses being built in flood-prone areas  
• infrastructure upgrades and improvements, where possible 
• buildings designed to withstand a flood.

Our approach prioritises high-risk areas so that our actions bring the most value to the community. Learn more about how we work with other organisations to manage flood risk together.