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

(Table 1) demonstrate that option 1 (Protect – Levee and stormwater infrastructure modifications)
provides the greatest net benefit to the community. This is driven by greater protection from
inundation leading to:

• avoided loss of tourism revenue

• avoided loss of benefits from access to recreational areas along the foreshore

• reduced road damage

• reduced damage to the stormwater network.

Option 2 (Accommodate – Road raising) has a similar discounted cost to option 1. However, it does
not provide as extensive protection from inundation and therefore delivers fewer benefits than option
1. The costs of option 2 may also be understated, as substantial modifications and community
inconvenience would be required to address matters such as driveway crossovers, grading of
intersections and pedestrian movements, which have not been included in the current costs.

Sensitivity analysis, which is included on pages 7-8 of the report, also demonstrates that option 1 is
the preferred option under a range of different assumptions.

Table 1: Present value results (discounted at 2.3 per cent, costs and benefits assessed for period
         2020-2100)

                                              Option 1 – Levee and      Option 2 – road   Confidence
                                              stormwater modification   raising

 Net Present Value (NPV)                      $21.5m                    -$3.9m

 Benefit Cost Ratio (BCR)                     2.11                      0.80

 Costs                                        $19.4m                    $19.2m

 Levee costs                                  $8.9m                                       Medium

 Stormwater modification costs                $10.5m                                      Medium

 Road raising costs                                                     $19.2m            Medium

 Benefits                                     $40.9m                    $15.3m

 Recreational benefits                        $6.5m                     $0.1m             Low

 Avoided property damage                      $0.1m                     $0.1m             Low

 Avoided road damage                          $1.1m                     $0.6m             Medium

 Tourism benefits                             $27.1m                    $10.8m            Low

 Avoided damage to stormwater                 $3.0m                     $0.6m             Medium
 network

 Residential nuisance benefits                $3.1m                     $3.1m             Low



Assumptions
All input assumption values used in the cost benefit analysis have been included in technical appendix
A.




REPORT | Noosa Shire Council CHAP – Phase 7                                                              3