6.5.22 - Flooding Report 5 may

      changed from 720min to the 120min, with the TUFLOW hydraulic model considered a better
      representation of flow routing within the catchment.
      Table 3-4: 1% AEP Peak Flow Comparison
                Parameter                                  Value                        Value
              Sub-Catchment                                  1A                           2C
             WBNM (Hydrology)                          8.1 (720min)                 33.0 (720 min)
            TUFLOW (Hydraulics)                        7.5 (120 min)                33.5 (120 min)
                  Difference                                 -0.6                        +0.5


      A comparison of the peak 1% (2100) AEP flood levels from the NSC flood search and TUFLOW
      model results from this investigation is presented below in Figure 3-1. This highlights that the
      estimated levels are a close match across the site with a levels at the downstream boundary
      of the site slightly higher in this current investigation (which is considered to create a
      conservative outcome). As such it is considered that a suitable verification between the NSC
      regional flood model and the current investigation has been achieved.




                                                           12.56
                                                           .36
             13.36




                                                                                                12.37
                                                                                                .36




                                                                                                12.37




                                                 13.00

      Figure 3-1: NSC Flood Search Levels (orange box) versus Site Model Results (white box)




21-0288-FS001-V5 | Flood Investigation | 60 Glenridge Drive, Cooroibah                                   |9