2021-10-08 SM - Item 1 - Attachment 2 - Draft Coastal Hazards Adaptation Plan - tracked changes

What are tidal inundation and storm tides?
As the sea levels rise, low-lying areas will be exposed to more frequent inundation under everyday
conditions and also with storm tides. In addition to a worsening of inundation in locations that
already experience it, some areas not previously exposed to inundation will also be affected. This
plan deals with two types of inundation hazard – permanent tidal inundation and storm tide. In
subsequent sections of this plan, these will collectively be referred to as ‘periodic tidal inundation’.


Permanent tidal inundation

As sea levels rise, the level of tidal waters increases in elevation in relation to the shoreline,
covering low-lying areas with sea water. In practice this will look like a very significant ‘king tide’.
Though instead of occurring every so often as occurs with ‘king tides’ today, it will instead occur
from two to three days per month in some locations, and almost every day in others (i.e. locations
close to the present-day shoreline) when the tide peaks. In the absence of any adaptation
response, this frequent or permanent inundation will mean in some areas the ground will be near-
permanently saturated, and in other areas, periods of reduced access to recreational areas, roads
and footpaths will cause nuisance to residents and visitors alike.

To understand how far this water may travel inland, tidal waters were modelled to show the
maximum extent under calm conditions. The results of this for the year 2100 can be seen in Figure
5. Additional images of permanent tidal inundation extent for the entire Noosa coastal zone across
other years can be found in Appendix 3. These map layers can also be explored in greater detail
using Council’s interactive mapping website.




Noosa Council – Coastal Hazards Adaptation Plan 2020 - 2030                                      Page 16