1909-13367 SRA referral response approved docs

                              Figure 8 – Developed Catchment Breakdown



4      2D M O DEL LI NG R E S ULT S


2D modelling of the existing case has been conducted in accordance with ARR 2016 using the
information detailed previously in this report.

The following section of this report with detail the results of the 1D/2D flood modelling using XPSTORM
version 2018.1. The key results that will be reported will be the peak water level and peak flow at key
locations which are depicted in figure 7 and 5 above.

Each design event will be presented both with and without blockage factors as defined in the previous
section.

The maximum design event that the bridge will be designed to is the 1% AEP event. The 1 in 500, 1 in
2000 and PMP events are presented as a sensitivity. Afflux will be presented for all design events up
to and including the 1% AEP.

The existing and developed flood immunity of Myall St and the rail corridor north of the site will be
commented on.

4. 1    4. 1 B as e C as e R esu lt s

The base or existing case has been modelled with a 2m 2 grid size with a 2d hydraulic timestep of 0.5
seconds. The results for the existing models are presented below.


4.1.1 50 % Ae p E xi st ing C a se R e sul ts (no b loc k ag e)

The maximum water level at reporting point 1 as extracted from the model was 105.85m AHD. The
surface level at this location is 103.83m AHD showing that the maximum depth of flow at this location
is approximately 2.02m.




                                               Flood Study                                          23
S19-007                                 122 & 144 Myall St, Cooroy