Hydraulic Assessment_compressed

            HYDRAULIC MODELLING

Based on Council’s flood overlay mapping, the project site is affected by flood from the eastern Branch of Kin
Kin Creek which runs through the property. Overland flow modelling, has been undertaken for the site and
surrounding area under the existing conditions to establish the level of inundation immunity for the
development. Overland flow modelling was conducted for the 1%, 10% and the 63% AEP design flood events.


The modelling was completed using the TUFLOW software 2020-10-AD package and LiDAR data sourced from
the Department of Natural Resources and Mines. Details on the development of the model and discussion of
the results are provided herein.



                   BASE CASE MODEL SETUP

            Topography

A Digital Terrain Model (DTM) was created for the study area using 1m resolution LiDAR supplied by the
Department of Natural Resources and Mines in conjunction with detailed site survey.

            Hydraulic Roughness Coefficients

Different Manning’s coefficients (n) have been applied to reflect the various land uses within the catchment.
This was achieved by defining polygons for the various land uses and assigning the relevant “n” value. The
study area was delineated based on the following land uses:
        •   Urban Area (default)           n = 0.06;
        •   Road/Carpark           n = 0.02;
        •   Light Grass            n = 0.035;
        •   Dense Woodlands n = 0.1;
        •   Buildings and Shed n = 1;
        •   Creeks/Waterway n = 0.07;

            Boundary Conditions and 1d infrastructures

Inflows were undertaken and TUFLOW’s automatic HQ relation was adopted at Downstream boundary and
existing culverts’ details were indicated in the Tuflow model key




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   2261 david low way, peregian beach, qld 4573      acn: 626 671 092          [email protected]