USC FloodStudyUpdate Report - Flipbook - Page 258
There are a number of ongoing projects within the Upper South Creek Catchment. Design levels for some
of these projects were available in the form of a triangular irregular network (TIN), which were read into the
model. These include:
The Northern Road,
Bringelly Road, and
Emerald Hills Estate.
There were several modifications made to this terrain to ensure topographic features were represented
correctly. These modifications are discussed in the following sections.
4.3.1. Roads
In areas where roads form a significant obstruction to flow or where flow paths cross under road
embankments, the crest of the road has been included in the TUFLOW model as a breakline. These
breaklines are sampled directly from the relevant terrain data (either LiDAR or the TINs above) and ensure
that road crests (the overtopping level of the road) are correctly represented in the model. This includes
some creek crossing locations where the LiDAR data displays the creek channel rather than the road
embankment.
In the urban areas, where a kerb and gutter system is present, the gutters have also been represented in
the TUFLOW model as breaklines which lower the terrain by 0.1 m. This enables the representation of the
conveyance of flows along street gutters in the TUFLOW model.
4.3.2. Basins
Generally the detention basins throughout the newly urbanised areas are well represented in the LiDAR
data. Some adjustments to the terrain have been made where the basin was under construction, or where
ponded water results in the LiDAR not representing the basin form properly. If data was available from
Development Application (DA) drawings, the basin inverts and spillways have been represented in the
TUFLOW model.
4.3.3. Dams
Rural farm dams are prevalent through the catchment. Breaklines for the crest of some of the larger dams
breaklines were sampled from the LiDAR data. The LiDAR survey cannot penetrate water surfaces and
hence the LiDAR data typically shows the water surface in areas where ponding occurs, such as these
farm dams. For the Pondicherry Dam, survey was available which included ground levels below the water
surface and this survey data was used to define the bathymetry of the dam.
4.3.4. Creeks
Breaklines have also been included for many of the creeks, to ensure that the creek invert is sufficiently
represented in the TUFLOW model and conveyance of water between the TUFLOW grid cells is adequate.
WMAwater Pty Ltd
118112: 201030_USC_Regional_Model_User_Guide_Final: 30 October 2020
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