1909-13367 SRA referral response approved docs

The initial loss for pervious areas is considered to be high as preburst depths are not proposed.
Therefore the initial loss has been reduced to compensate for the absence of prebursts. Please see
below adopted initial and continuing losses below.
          Pervious Area

                                  Initial Loss 15mm
                                  Continuing Loss 2.6mm/hr



      Impervious Areas

                                  Initial Loss 0mm

                                  Continuing Loss 0mm/hr
Preburst depths

Prebursts have not been adopted for any of the models mentioned in this report.


3.1.5 Ra inf al l t em po ra l pat t e rns

XPStorm has incorporated the temporal patterns from ARR DataHub for the given site location (-26.445,
152.897) sourced on the 30 March, 2019 within the east coast north region.

These temporal patterns have been used to determine the critical storm duration for each of the design
events.

Areal reduction factors have been incorporated into the model as required, which were sourced from
ARRdatahub for the above mentioned coordinates and date.


3.1.6 1D H yd r aul ic m od el l a yout

In order to approximate the natural flow of the external catchments a 1D link and node model has been
constructed. 1D links have been run along the alignment of the creek beds within each catchment from
the top to the bottom of the model study area (depicted in figure 3). 1D runoff nodes representing the
hydrology of each sub-catchment have been placed at the ends of each reach of the creek with the
hydrologic parameters as shown in table 1. To ensure that the 1D accurately reflects reality each 1D
link has been set with the cross section of each catchments midpoint. The 1D model extends to the
beginning of the 2D model bounds. The layout of the 1D is shown in figure 3 below.




                                               Flood Study                                         11
S19-007                                 122 & 144 Myall St, Cooroy