A storm surge is a rise in sea level being pushed towards shore due to winds associated with severe storms, east coast lows or cyclones. This rise in water level can cause extreme flooding in coastal areas, particularly when storm surge coincides with the astronomical high tide; this occurrence is known as Storm Tide and is depicted below. The predicted increase in frequency and severity of cyclones impacting Queensland further to the south combined with rising sea levels, are likely to result in more extreme storm tides and a greater potential for flooding along the coastal regions of Redland City.
In deeper water, a surge can be dispersed down and away from the cyclone. However, upon entering a shallow, gently sloping shelf such as Moreton Bay, the surge cannot be dispersed, but is driven ashore by the wind stresses of the cyclone. Height above sea level and topography of the land are critical factors in the extent that a storm surge will impact coastal areas. Locations where the land is less than a few meters above sea level are at particular risk of storm surge inundation. The severity of the storm tide is also dependent on the position and path of the storm system in relation to Moreton Bay. Waves resulting from wind directed from the north‐east or east will have maximum effect on the water levels in Moreton Bay.