What is a Storm Surge

A storm surge is a rapid rise in sea level generated by the low atmospheric pressure and gale force onshore winds experienced during a tropical cyclone.

Storm surges can cause inundation of low-lying coastal areas.  The combination of a storm surge and a normal ocean tide is known as a ‘storm tide’.

The Storm Surge Map shows inundation at 1 Metre, 2 Metres, 4 Metres and 6 Metres above Highest Astronomical Tide.

The different colours (Red, Orange, Yellow and Blue) indicate the separate areas that may be affected depending on the size of the storm surge predictions.  After a cyclone has passed and the threat of a storm surge is evident,  the Burdekin Shire Council will act depending on the advice given from the Bureau of Meteorology as to the predicted height of the expected storm surge (1m, 2m, 4m, 6m) and inundation.  Based on this information residents in those areas may be evacuated.

What is a Storm Tide?

A storm tide is a rise above the tidal water level along a shore that is associated with a tropical cyclone.  Storm tides will be accompanied by gale force winds, with successive waves of seawater rapidly moving across the foreshore.

When a cyclone forms over open waters the strong winds pushing the water, combined with the low atmospheric pressure in the eye of they cyclone cause the level  of the sea to rise, which results in the formation of large waves.

If this happens away from land, the water can escape and move freely away from the building storm.  As the cyclone moves towards land and the depth of the water becomes shallower, the ever-increasing wall of water does not have a chance to flow away.  These waves may inundate land and cause destructive damage to anything in its path.  Trees, building material and other debris may be carried along by the storm tide.  Any evacuation must occur prior to the storm tide event.

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storm tide and storm surge zones for Burdekin Shire

What is HAT?

HAT stands for Highest Astronomical Tide, which is comparable to a king tide.  It is the highest level of water, which can be predicted to occur under any combination of astronomical conditions.  The Bureau of Metrology (BOM) advices regarding storm tide will refer to a height (in meters) above HAT.  Council will use this BOM information to advise which zone may be affected.

Storm Tide Evacuation Zone Maps

How to use the Storm Tide Evacuation Maps

  • Identify where your residence is on the map.
  • If you are in one of the coloured zones, you may be at risk from storm tide flooding during cyclones.
  • Identify your evacuation route to your pre-determined safer location.
  • During a cyclone event tune into warnings.
  • Authorities will advise which zones need to evacuate.

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