The danger of storm surge
The risk of storm surge is the most dangerous hazard associated with cyclones and can cause flooding of low-lying coastal areas. Most cyclone-related deaths are from drowning in a storm surge or flood.
Storm surges happen when the high winds of a cyclone whip up the sea, generating a massive movement of seawater inland that can last several hours. They are at least 50 kilometres wide and can be up to several metres high. Storm surges can swamp coastal areas. Low offshore islands may be completely inundated. The damage is worse when a storm surge coincides with high tide or river flooding. The combination of storm surge and normal ocean tide is known as ‘storm tide’.
Figure 1: STORM SURGE + HIGH TIDE = STORM TIDE
The storm surge from Cyclone Yasi in 2011 virtually destroyed the main street of Cardwell in North Queensland, washing away sections of road and leaving a massive trail of sand and debris. Nearby Port Hinchinbrook marina was decimated. About 60 boats littered the foreshore and nearby streets after being torn from their moorings.
Get ready for storm surge
The best option for every Queenslander, when evacuation is not necessary, is to shelter in place in a well-maintained building. Often this will be your home.
However, if you live in a low-lying coastal area or consider your home unsafe, you may need to evacuate.
Is it safe to shelter in place?
When thinking about the likely safety of your home in a cyclone or storm surge event, consider:
- The age of the building. Buildings established after 1982 are, in general, more likely to withstand wind speeds of up to 250 km/hr (equivalent to a Category 4 cyclone) due to design specifications introduced at that time.
- The location of the building. Check with your local council whether you live in an evacuation zone. Buildings in evacuation zones may be at risk of inundation during a storm surge or storm tide.
Is it best to evacuate?
Residents living in evacuation zones in low-lying coastal areas are urged to call on their friends or family members who live in safer places for shelter in case they need to evacuate before a storm surge.
Storm tides can damage and destroy buildings, cut off evacuation routes and cause injuries and fatalities. Don’t wait for a cyclone or storm surge to happen before you think about how you and your family are going to survive. Take the time now to plan for an evacuation.
An evacuation order may be issued if lives are at risk. Police and emergency services may need to commence evacuations at short notice. Residents need to stay informed about the situation through local radio, television, internet and credible social media sites. You put yourself and your family at great risk if you do not evacuate when requested.
If you live in an evacuation zone, establish an evacuation plan to shelter with friends or family who live in a well-maintained home, constructed after 1982, that is outside the identified risk areas. Make plans now, before a disaster strikes.
If you live outside an evacuation zone, you can support family or friends who do by offering them the option to come and shelter with you in case they need to evacuate.
Storm surge is generated by the low atmospheric pressure and gale force onshore winds experienced during a tropical cyclone. The worst impacts can occur when a storm surge arrives on top of a high tide (known as a storm tide).
Refer to your local council for more information about storm tide evacuation zones and evacuation routes.
For information on what to do before, during and after a cyclone (and associated storm surge) event, visit http://www.emergency.qld.gov.au/emq/css/cyclone.asp.
Last updated 22 November 2012