Reference Documents RAL21 0035

Table 3.3 – Pre-Development Flood Depths and Depth Velocity

  Point         1%                1%              10%          10%           50%              50%
   ID         Critical          Critical         Critical     Critical      Critical         Critical
              Depth               dxV            Depth          dxV         Depth              dxV
  1         0.654                0.881            0.534        0.594         0.325            0.312

  2         0.731                 1.200           0.633        0.788         0.490            0.417

  3         0.777                 1.061           0.672        0.669         0.513            0.319

  4         0.982                 1.158           0.752        0.806         0.491            0.429

  5         0.635                 1.009           0.510        0.656         0.359            0.299

  6         0.984                 1.152           0.873        0.697         0.709            0.398

  7         1.087                 1.038           0.921        0.713         0.709            0.353



Table 3.4 – Post Development Flood Depths and Depth Velocity

  Point         1%                1%              10%          10%           50%              50%
   ID         Critical          Critical         Critical     Critical      Critical         Critical
              Depth               dxV            Depth          dxV         Depth             dxV
  1         0.177                0.230            0.058        0.061           -                -

  2         0.090                 0.022              -             -           -                 -

  3         0.175                 0.071              -             -           -                 -

  4         1.135                 1.011           0.967        0.712         0.731            0.445

  5         0.639                 1.002           0.510        0.656         0.359            0.299

  6         0.973                 0.757           0.863        0.429         0.702            0.200

  7         1.086                 1.046           0.919        0.713         0.709            0.345



At the location of the culvert (POI 1 to 3), the road is now trafficable during the 1% and 10% AEP storms (depth <
0.2m and dxV <0.3m/s² as per QUDM Table 7.4.5) and immune under the 50% AEP storms as per the immunity of
Jirrima Crescent.
Although the culvert upgrade results in increased depth of flow upstream of the crossing, the impacts are
contained within the heavily vegetated riparian buffer zone and areas of biodiversity significance overlays where
development would be prohibited and no impacts to property and infrastructure nor adverse use of the land is
anticipated. At a location 50m upstream and downstream of the site, the difference from the existing flows are
negligible, therefore impacts to adjacent properties are within an acceptable limit.

Refer to Appendix C TUFLOW Modelling Flood Maps for maps showing the results of the modelling.




Project number 20220089                                                                                             Page 14 of 23
File 20220089 Jirrima Cr SWMP.docx, 2023-05-09 Revision 0


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