Storm Surge
Ignore a storm surge and you'll be in deep water!
A storm surge is a raised dome of sea water typically 60km to 80km across and 2 metres to 5 metres above the normal sea level.
As a cyclone reaches the coast the huge winds whip up the sea and push the dome of water over low-lying coastal areas.
The waves and sea water 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 tidal wave (which is a towering wall of sea water which comes crashing into shore). 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 following:
- The intensity of the cyclone - the stronger the winds the higher the surge.
- The angle at which the cyclone 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, head lands or islands can funnel the surge and amplify its height.
If the cyclone crosses the coast at high tide, the flooding will be at its worst.
History - Australia's worst storm surges
The whole of coastal Queensland is at risk of cyclones and storm surge, 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 as many as 1000 homes.
More recently, there have been a number of close calls such as Cyclone Althea in 1971 which produced a 2.8 metre storm surge in Townsville. Thankfully it crossed the coast near low tide so there was only minor flooding. If Althea had struck just five hours later on the high tide a tragedy could have occurred.
At the beginning of the storm and cyclone season (September)
There are a number of simple things that you and your family can do to stay safe and protect your property.
- Check that your home is in a sound condition, especially the roof and eaves.
- Trim any tree branches hanging over your roof.
- Clear your property of any loose items that may blow about.
- Check that you have adequate household and contents insurance and which hazards are not covered by the policy.
Prepare an emergency kit containing
- A portable radio, torch and spare batteries;
- Stocks of fresh water and canned food;
- Matches, fuel lamp, portable stove, cooking gear, utensils and can opener;
- Waterproof bags for clothing and valuables;
- A first aid kit and manual.
Keep a list of emergency phone numbers handy, including numbers for your local Police, Fire, Ambulance, State Emergency Service, Local Council, Gas and Electricity Company and relatives.
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.
- Consider which indoor items you will raise (eg furniture, clothing etc.) or empty (refrigerators, freezers etc.) if water threatens to enter your home.
- 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 as well as you 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, tables and 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.
- Whether you leave or stay, 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
Last updated 8 December 2010
Other languages