2021-01-18 GC - Item 3 - Attachment 1 - Coastal Hazards Adaptation Plan for Community Consultation

Fact sheets about the adaptation options subject to a cost-benefit analysis, including those
described above, can be found on the project page on Your Say Noosa.


Options for responding to coastal inundation risks
Water levels in the lower Noosa River and its tributaries (including the lakes) can become elevated
due to a number of factors including rainfall across the catchment area, a storm tide, or during
sunny days as a result of higher than average tides. The area of land subject to the effects of storm
tides is expected to increase as a result of sea level rise. In addition, the reach of tidal waters is
going to increase beyond what we currently identify as the shoreline and this is also due to
increases in sea level.

Flood management measures are currently in place in Noosa Shire to help manage the risks of
flooding as a result of high rainfall in the catchment (referred to as catchment flooding). These
include:
     • stormwater drainage works and flood mitigation works in high-risk flood prone areas
     • planning controls through the Noosa Plan 2020 that set development requirements such as
         minimum levels for new buildings and filling limits for land subdivisions and other works
     • flood modelling and mapping identifying areas at risk for different flood severities
     • Disaster management responses during major flood events.

These catchment flooding measures will also help Noosa manage and adapt to changes to storm
tide inundation. For example, the minimum floor levels for new houses or units in Noosaville will
ensure that these developments are safeguarded from direct physical damage from storm tide
inundation.

However, the impacts of frequent tidal inundation of low-lying areas (particularly the parks, road
reserves and some private properties around the Noosa River) require further management action
overtime. Some riverside areas are already affected by infrequent events such as catchment
flooding and storm tide inundation. The relatively long periods of time between events allow for
clean-up, recovery and repairs to be undertaken, and normal activities to resume unimpeded.
However, activities and assets in these areas are unlikely to cope with impacts caused by frequent
tidal inundation. As sea levels rise, some low-lying areas will be regularly covered with shallow sea
water. In the absence of any adaptation response, this will restrict access to roads, footpaths and
recreational areas and cause nuisance to residents, business owners and visitors.

The cost benefit analysis of coastal inundation risks (Aither 2020b7) assessed that a number of
adaptation options are likely to be both suitable and feasible for responding to the risks associated
with frequent tidal inundation in Noosa’s coastal zone. These include:

      •   Continuing existing measures for responding to risks of catchment flooding and storm tide
          inundation
      •   Protecting buried infrastructure (stormwater and sewerage assets) through installation of
          innovative technologies
      •   Reducing the frequency of inundation to roads, pathways, parks and business areas
          through the creation of adaptive landscape measures. This includes low rise levies and
          landscaped walls along some foreshore edges, elevated footpaths and improvements to
          drainage
      •   Ensuring asset plans and upgrades appropriately consider inundation risks.

Fact sheets for these adaptation measures can be found on the project page on Your Say Noosa.


7
    Aither, 2020b. Noosa Shire Council CHAP – Phase 7, Noosaville Cost Benefit Analysis
Noosa Council – Coastal Hazards Adaptation Plan 2020 - 2030 (community consultation version)   Page 28