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Storm surge

Storm surges—being prepared and staying safe

A storm surge is a raised dome of sea water typically 60km to 80km across and 2–5m above the normal sea level. They are caused by strong winds and areas of low pressure created by a cyclone or severe storm.

As the storm reaches the coast, huge winds whip up the sea and push the storm surge over low-lying coastal areas.

Storm surges can move inland quite quickly, damaging buildings and cutting off escape routes. There is a high risk of drowning.

A storm surge is not the same as a tsunami, or tidal wave. A storm surge comes in like a rapidly rising tide, but it can be extremely dangerous and destructive.

The height of the storm surge will depend on:

  • the intensity of the storm—the stronger the winds the higher the surge
  • the angle at which the storm crosses the coast—a right-angle crossing will increase the surge
  • the shape of the sea floor—the more gentle the slope, the greater the surge
  • local features such as bays, headlands or islands can funnel the surge and amplify its height
  • existing tidal conditions—if the cyclone crosses the coast at high tide, the flooding will be at its worst.

Preparing for a storm surge

There are some simple things that you and your family can do to stay safe and protect your property.

When a severe storm surge seems likely...

  • Listen to your local radio station for warnings and advice. Don't use your phone unless it is essential.
  • Prepare to move vehicles, outdoor equipment, garbage, chemicals and poisons to higher locations.
  • Decide which indoor items you will raise (e.g. furniture, clothing) or empty (refrigerators, freezers etc.) if your home may be flooded.
  • Check your emergency kit and consider what you will do with your pets.

If you need to evacuate...

  • If you decide to leave of your own accord, make sure you tell the police or your local State Emergency Service and your neighbours.
  • Make sure you pack warm clothing, essential medication, valuables, personal papers, photos and valuables in waterproof bags, to be taken with your emergency kit.
  • Raise your furniture, clothing and valuables onto beds and tables and into the roof space (place electrical items as high as possible).
  • Empty and turn off refrigerators and freezers, leaving the doors open to help prevent them floating about.
  • Turn off the power, water and gas and remember to take your mobile phone.
  • Put sandbags in toilet bowls and over all laundry/bathroom drain-holes to prevent sewage back-flow.
  • Lock your home (remembering to take your keys) and take the recommended evacuation routes for your area.
  • Don't drive into water of unknown depth and current.

Australia's worst storm surges

The whole of coastal Queensland is at risk of cyclones and storm surges, with some areas more vulnerable than others. Destructive storm surges don't happen very often, but as our coastal population grows, the risk increases.

In 1899 at Bathurst (near Cape York), a massive storm surge killed more than 300 people.

In 1918, a storm surge inundated Mackay, drowning 13 people and damaging or destroying around 1000 homes.

More recently, there have been several close calls, such as Cyclone Althea in 1971, which produced a 2.8m storm surge in Townsville. Thankfully, it crossed the coast near low tide so there was only minor flooding. If Althea had struck at high tide (just 5 hours later) a tragedy could have occurred.

Don't ignore the dangers

Don't drive through floodwater

Each year, emergency services receive calls for help from people who have ignored traffic signs and road closures and become stranded in floodwater—putting themselves and their rescuers at risk. Think about the consequences of your actions. Don't risk your life or the lives of others.

Don't play in or around floodwater

Children drown every year in floods. Warn children of the dangers—don't let them play in or around floodwater

Storm tide

The combination of storm surge and normal ocean tide is known as a 'storm tide'. The worst impacts can occur when a storm surge arrives on top of a high tide. When this happens, the storm tide can reach areas that might otherwise have been safe. If you live in a low-lying tropical or sub-tropical coastal area, you could be at risk from storm tide inundation.

Contact your local council to find out if your home is in a storm tide evacuation area. If it is, arrange a safer place for your evacuation as part of your preparations.

Last updated
21 November, 2011
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