2021-01-18 GC - Item 3 - Attachment 3 - Cost Benefit Analysis for Coastal Erosion Options

2.2.         Project options
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. This process has resulted in
seven main options (including the base case) for inclusion in the CBA.

The options analysed in this report are broadly described in Table 1 and vary based on the landward
assets they protect and future beach width they provide or influence. The options are compared with a
base case that assumes no coastal adaptation or risk mitigation efforts are undertaken. The CBA
assesses the net change in the costs and benefits of each option relative to this base case. Not all
options are undertaken immediately, but from the point in time needed to avoid the effects of coastal
erosion. We did not undertake any additional analysis around timing of impacts and investments.
There is limited data on different timings for coastal erosion impacts given changes in investments.

Table 1         Summary of coastal adaptation options evaluated

    Option                 Description
    Option 1 (base         Do nothing approach. No risk mitigation efforts undertaken between present
    case)                  day and 2100.
                           Dune revegetation and management undertaken every 5 years, from 2020
    Option 2
                           until 2100.
                           Dune augmentation, revegetation and management undertaken every 5 years,
    Option 3
                           from 2020 until 2100.
                           Armoured rock revetment for all beach compartments identified as High or
    Option 4               Very High risk by 2100 (Sunrise and Sunshine beaches only). Constructed in
                           2040.
                           Acquisition of all properties followed by rezoning of land to public open space
                           that supports natural coastal processes1. Acquisition to occur 30 years prior to
    Option 5
                           identified erosion impact. Conversion of acquired lots into public recreation
                           areas.
                           Acquisition of all properties where lot size does not support sufficient building
                           size and setback due to coastal erosion. Acquisition to occur 30 years prior to
    Option 6               identified erosion impact. Leaseback of buildings for 15 years after acquisition.
                           Conversion of acquired lots into public recreation areas when lease period
                           ends.
                           Changes to planning provisions to prevent development within the projected
                           2070 coastal erosion prone area. Dune revegetation and management over a
    Option 7
                           5-year life. Undertaken until 2100. This option is only assessed for the Eastern
                           Beaches and not for Teewah.
Source: Noosa Shire Council and BMT


Options 2 and 3 are undertaken until 2100 regardless of any reduction in their effectiveness in the
intervening years. This is done so that all options are being compared on an equal temporal basis. It
also assists decision makers understanding when, if implemented, these options are no longer


1
    Assuming a minimum building size of 180m 2 and the required 6m frontal boundary setback and 2m side boundary
       setback



AITHER | Final Report                                                                                              8
Noosa Shire Council – Coastal Hazard Adaptation Plan