Who is responsible for forecasting floods?
The Bureau of Meteorology is responsible for forecasting riverine flooding across Australia. This helps protect lives, property and livelihoods as part of the total flood warning system.
Our role is to provide states and territories with riverine flood forecasts and warnings. This enables emergency services to support disaster preparedness, response and recovery.
Who forecasts river flooding?
When there is a risk of riverine flooding, our experts forecast:
- how high rivers are expected to rise at certain locations
- the likely timing of flooding.
We often need to produce or update forecasts quickly, as weather and river conditions can change fast. To forecast floods, we:
- monitor how much rain has fallen and changing river heights
- assess soil moisture and how the river and catchment are likely to behave
- estimate when the river is likely to be at peak height during a flood.
We use this information to prepare and issue flood watches and warnings, on our Warnings and alerts page and the BOM Weather app.
Working with state and territory partners
Our team of flood data specialists, meteorologists, hydrologists and flood forecasters also work with partners, including emergency services and local government, to understand the:
- local situation, such as new drainage channels or river levees
- historical significance of current conditions by comparing them with recent and past floods.
We use this information to support emergency services as they alert and help affected communities.
Who forecasts flash flooding?
Because it develops so quickly, flash flooding cannot always be forecast.
We issue severe weather warnings and severe thunderstorm warnings when heavy or intense rainfall is forecast or occurring that may lead to flash flooding.
State, territory and local governments are responsible for providing flash flood warnings.
Who forecasts coastal flooding?
The bureau:
- measures and predicts sea level and tides
- monitors tsunami activity across the Australian region
- monitors sea levels and storm surge that may lead to coastal flooding
- issues warnings for storm tide, abnormally high tides and damaging surf.
Learn more about coastal hazard warning services.
How are floods forecast?
There are many aspects to forecasting floods. It is a complex process, and we respond quickly to changing conditions. Flood forecasting services include assessing flood potential and estimating river levels.
Assessing flood potential and estimating river levels
We assess the risk of riverine flooding every day across river catchments across Australia. Long before rainfall is recorded on the ground, we assess the potential for flooding.
We use 3 main inputs to assess flood potential and estimate river levels.
1. Weather and rainfall forecasts
Weather forecasts help us understand how much rain may fall, where it could fall and how intense it might be.
2. Observations
To understand how much rain has fallen and current conditions, we use data from a range of sources, including:
- rainfall and river height data from more than 10,000 gauges across Australia
- information from satellites and radars.
Learn more about our observation network and equipment.
3. Modelling and tools
We also use a suite of tools to examine how river levels may respond and what this might mean for the community. This includes specialised computer models and tools to estimate river levels. These are generally based on rainfall forecasts over river catchments and how wet or dry the soils are.
These tools also use insights from recent and past floods to help show what may happen.
Types of flood forecasts
Our riverine flood warnings can include 3 types of flood forecasts:
- quantitative
- qualitative
- generalised.
The forecast types used in each state and territory are set out in our service level specifications for floods and are regularly reviewed.
Quantitative forecasts
Quantitative forecasts are the most common type of forecast we provide for specific locations.
We issue quantitative forecasts when we have enough data and modelling information to make detailed predictions.
These forecasts include:
- the expected flood classification level (minor, moderate or major)
- the expected river height at a specific location
- when the river is likely to be that height.
An example for New South Wales includes:
'The Clarence River at Grafton is expected to peak near 6.5 metres with major flooding around 6 pm on Sunday'.
Qualitative forecasts
Qualitative forecasts provide:
- the expected flood classification level (minor, moderate or major)
- an approximate time when flooding is expected at a location.
These forecasts are less precise than quantitative forecasts.
An example for Queensland includes:
'Minor flooding is expected in the Murray River at Murray Flats during Saturday afternoon and is expected to peak above the major flood level during Sunday evening'.
Generalised forecasts
We issue generalised forecasts in our riverine flood warnings when less information is available or when a flood is still developing.
These are based on rainfall forecasts and knowledge of how rivers have responded to past floods.
Generalised forecasts may describe flooding across a catchment, rather than at specific locations. They may include information about rising or falling river levels.
An example for Victoria includes:
'Significant flooding is expected in the Genoa River catchments during Saturday with further rises possible due to forecast rainfall'.
Supporting our partners when floods are forecast
Managing floods and other severe weather emergencies is a shared responsibility in Australia involving:
- federal, state and local governments
- emergency service agencies
- non-government organisations, such as charities and community organisations
- community and volunteer groups
- individuals.
The bureau provides daily briefings to local disaster and emergency management agencies before and during riverine flood events. This includes advice on early forecast information and the likelihood of flooding.
When flooding is likely
When flooding is likely, we work closely with water agencies and catchment authorities managing water storages. We also collaborate with state, territory and local government emergency managers to:
- keep communities informed
- assess flood impacts
- support planning and decision-making.
When flood risk increases, this service operates 24 hours a day, 7 days a week.
During floods
During emergencies such as floods, expert bureau staff form part of national and state situation rooms. These 'embedded' meteorologists and hydrologists provide crisis managers with critical information to support decision-making. Learn more about the work of an embedded meteorologist on our Emergency management page.
We update forecast river heights as more information becomes available or flood risk changes. We include these updates in our flood warnings.
Every flood event is different. In rapidly changing situations:
- flood warning information can be updated as often as every 3 hours
- rainfall and river level data for affected catchments are updated every 15 minutes.
We use our suite of tools to assess how rivers may respond and what this could mean for communities. These tools use insights from recent and past floods to help show what may happen.