Hastings St, beachfront homes at ‘high risk’ of rising sea
Noosa community consultation shows most residents rejecting hard engineering solutions like tidal gates at the river mouth to hold back storm surges and rising sea levels impacting Noosaville over the next 80 years.
Instead, feedback from public workshops held by Noosa Council favoured the raising of buildings and road levels.
However, experts preparing the council's coastal hazard adaptation plan have found the best protection could be levees that would need to be built by 2070 to counter inundation.
They put the levee costs at $8.9 million while associated stormwater system protections against saltwater inundation was costed at $10.5 million.
Along the coastal strip residents favoured using "nature-based solutions" solutions such as beach management and dune augmentation to combat increasing erosion impacts.
An adaptation plan project summary prepared by BMT, an international design engineering risk consultancy, said permanent sea level rise inundation along Noosaville was expected to be high or very high by 2070 through to 2100.
The BMT report warned most Hastings St properties on the foreshore side would be very at high risk from erosion "without the application of further mitigation measures".
Noosa's most famous street and the national park entrance are also at high risk of being cut off by rising water along Noosa Dr by 2100.
Noosa Spit's sand shifter system, which pumps sand onto erosion prone Noosa Main Beach, is predicted to be at high risk by 2040 and could be rendered inoperable for up to six months of the year.
BMT said the southern section of the Noosa Spit's Dog Beach was facing an increased potential from ocean breakthrough to Noosa Sound.
"Erosion may also have a high impact on infrastructure within the southern end of the (Spit) reserve such as dune vegetation, car park areas and public amenities," the BMT summary said.
Noosaville areas identified at high to very high permanent sea level rise by 2100 included
about 35 lots in the area bounded by Russell St to Weyba Rd, Gympie Tce to Noosa Pde.
They also included about 80 lots including about 40 homes bounded by Robert St to Eumundi-Noosa Rd.
Another 49 dwellings at the western end of Noosaville bounded by Hilton Esp, Earl St, and Hilton Tce were included as well as about 30 lots bounded by Lake Weyba Dr and Noosa National Park.
BMT said Tewantin's Noosa River conservation parks of Sheep, Goat and Makepeace islands were ranked at high risk from permanent sea level rise by 2070 while the risk to the Lake Doonella wetlands would also become high by then.
Along the open beaches the report had options for property buybacks for at risk erosion zones.
BMT said the construction of seawalls had "the least socio-economic benefit due to loss of amenity, low community support, impacts on the tourism economy, and cost of construction".
There are 22 properties at Sunshine Beach which have been rated by BMT as at high risk of erosion by 2040.
By 2070 about 72 properties will be at high to very high risk at Sunshine and Sunrise beaches, increasing to 109 properties by 2100.
"No private properties south of Sunrise Beach have been assigned a high or very high risk, with the highest being a medium risk by 2100 for those assets south of Peregian Park," the summary said.
About 24 lots at Teewah Beach on Noosa North Shore are considered to be at high risk by 2100.
The costal hazard adaptation plan will go before Noosa Council this week for adoption before going out for further public consultation.