About storms and floods in Tasmania

Tasmania lies in the path of the Roaring Forties wind that encircles the globe. Storms and severe weather affect all parts of Tasmania at any time of the year. They can include heavy rain leading to flooding

Severe storms

Severe storms can include

  • torrential rain
  • strong winds
  • large hailstones and
  • lightning.

Storms can cause flash flooding and major damage to

  • Trees
  • buildings and
  • powerlines.

Even if floods or storms do not damage your property, you may lose

  • power, phone and internet connection, or
  • road access.

See more information about severe weather from the Bureau of Meteorology.

Flooding

A flood is when water covers a normally dry area. Flooding is one of the most dangerous risk natural hazards in Tasmania. Since European settlement there have been at least 78 flood-related deaths in Tasmania. Estimated costs of some more recent flood events are:

  • 2011 floods – $24 million
  • 2016 floods – $180 million
  • 2018 Southern Tasmanian Extreme Weather Event May 2018 – $135 million

Different types of flooding

  • Riverine flooding is flooding from rivers. When there is too much water, rivers and other waterways burst their banks.
  • Flash flooding is caused by heavy rain falling faster than it can flow away. Flash flooding occurs within 6 hours of heavy rainfall. It is difficult to predict flash flooding. 
  • Overland flooding is rainwater run-off across the landscape before it reaches a waterway like a stream, creek or river. Water can flow over roads and properties. It is sometimes called stormwater run-off.
  • Coastal inundation is when very high tides and/or low-pressure weather systems cause sea-water flooding near the coast.
  • Dam failure causing flash flooding downstream

Describing different levels of flood impacts

Depending on the estimated flood depth and expected consequences, the Bureau of Meteorology will describe a flood of Tasmania’s larger river systems as

  • Minor
  • Moderate or
  • Major.

See more information about the Bureau’s flood warnings.

SES issues flood warnings on the basis of the Bureau’s flood predictions – see more information about flood warnings in Tasmania.

Minor flooding –flooding causes inconvenience due to water across

  • Minor roads
  • Agricultural land on flood plains
  • River side parks
  • Some backyards and buildings below floor level.

Moderate flooding –water may affect

  • some main traffic routes
  • some buildings above floor height. Some people may need to evacuate
  • larger areas of agricultural land, parklands and other low lying areas.

Major flooding – extensive flooding potentially

  • Affecting many building above floor height so people need to evacuate
  • Cutting major transport routes
  • Isolating communities
  • Cutting essential services such as water, power and telecommunications.

For more information and definitions about floods, see

Flood likelihood and expected impacts

Annual Exceedance Probability (AEP) is the chance of a given level of flooding happening in a year.  A 1% AEP flood has a 1% (or 1 in 100) chance of occurring or being exceeded at a location in any year. This is based on rainfall records for the area.

Floods will happen

Floods are a natural part of the environment. In fact, some ecosystems rely on them. For example floodplains often have rich soil built up over many years due to repeated flooding. Some of Tasmania’s best farming land is on floodplains.

Flooding becomes a problem when we build homes and other assets in places that are prone to flooding. It is important to think about potential flooding when buying or maintaining property. Flood mapping can help with land use planning, so homes and other assets are not built in flood-prone places. If we do build assets in flood-prone areas, we need to consider flood risks.

Reducing flood risk

There are ways to reduce flood risks, for example, through

  • land use planning, avoiding building in flood prone areas
  • building controls, to make buildings in flood-prone areas able to withstand floods
  • physical measures to divert or reduce floods, such as levees and detention basins
  • Preparedness – being ready for floods reduces impacts of floods and recovery afterwards.

Places like Launceston and Longford have levees.  However, these types of measures

  • are expensive and need to be carefully planned and built, or
  • they can cause problems in surrounding areas. 

Levees can protect existing properties in flood prone areas. They should not be used for new developments. In severe floods, people living behind levees often need to evacuate as a precaution.

Everyone should get ready for floods, even if they live in a place not prone to flooding.  Floods and associated storms often

  • cause power outages
  • cut roads/ access routes
  • cause drinking water shortages.

Due to the state’s shorter river systems, areas often have storms alongside floods. Storms, floods and heavy rain can also cause other hazards such as

  • Landslides and debris flow
  • Dam safety issues
  • Extended power cuts
  • Coastal inundation / coastal storm surge