2021-01-18 GC - Item 3 - Attachment 4 - Cost Benefit Analysis for Noosaville Inundation Options

Noosaville Cost Benefit Analysis

Introduction
Aither was engaged, in partnership with BMT, to undertake a socio-economic analysis of potential
climate change adaptation options for the Noosaville area of Noosa Local Government Area (LGA). At
this stage of investigation, the socio-economic analysis aims to:

• support Noosa Shire Council’s understanding of the merit of different options

• assist Council to communicate the benefits and costs of options to stakeholders

• determine next steps for more detailed investigation.

The socio-economic analysis investigated the effects of sea level rise between 2020 and 2100.
Modelling undertaken by BMT in Phase 3 of the CHAP shows that sea level rise (relative to present day
extents) will lead to increasing risk of low-level inundation1 of the areas in Noosaville adjacent to the
Noosa River, creeks and lakes. If no management activities are undertaken, the risk to assets at these
locations progressively increases. These effects have been assessed at nominal timeframes of present
day, 2040, 2070, and 2100, selected to align with increases in sea level of 0.0m, 0.2m, 0.4m, and 0.8m
respectively.

The effects of low-level inundation include damage to public and private assets, and impacts on the
local community including reduced access to recreational areas, loss of tourist expenditure, and
disruption to residents from road closures. The effects on non-tourism businesses were not calculated
at this stage, as the temporary and occasional nature of the inundation indicates that other business
would see a delay in sales, rather than an overall decrease.

As part of the CHAP, technical investigations into potential adaptation options have been undertaken
by coastal engineers (BMT), including high-level cost estimates. A range of coastal adaptation options
were developed through earlier stages of the CHAP in consultation with the local community. The full
range of potential options were examined through a multi-criteria analysis (MCA) undertaken by BMT.
Those that scored highest in this process, or were considered to likely be of broader interest, were
included in the CBA. Aither’s analysis therefore assessed the following adaptation options:

• Option 1: Protect - Levees and stormwater infrastructure modifications (i.e. installing tide gates to
  prevent egress into the stormwater network)

• Option 2: Accommodate - Road raising

This report provides findings for Phase 7 of the CHAP: Socio-economic appraisal of adaptation
options of the Noosa CHAP in line with the QCoast2100 CHAP minimum standards and guidelines.



Findings
The cost benefit analysis assesses the net benefits and costs over an 80-year period (2020-2100), using
a discount rate of 2.3 per cent reflecting Noosa Shire Council’s current cost of borrowing. The results


1
    Inundated to depths of approximately 0.1m for less than an hour per day, occurring for roughly two consecutive days
       every fortnight. Information on low-level inundation has been provided by HydraLogic.




REPORT | Noosa Shire Council CHAP – Phase 7                                                                               2