USC FloodStudyUpdate Report - Flipbook - Page 259
4.4. Surface Roughness
Surface roughness values have been defined across the TUFLOW 2D domain, represented by the
value, as outlined in
Table 5.
Table 5
Values Adopted in the TUFLOW Model
Land Use Category
Bare earth
0.02
Maintained grass / parks / ovals
0.03
Floodplain grass / pasture
0.04
Light vegetation
0.045
Medium vegetation
0.06
Dense vegetation
0.08
Riparian vegetation
0.12
Creeks and open water
0.03
Roads
0.02
Road corridor
0.035
Paved areas
0.02
Low density (rural) residential
0.045
Medium density (urban) residential
0.06
Industrial / commercial / schools
0.03
Railway
0.06
4.5. Buildings
Buildings were represented as solid obstructions to flow by blocking them out of the TUFLOW grid. The
buildings layer provided with the capture of LiDAR data was used to represent the building footprints.
4.6. Pit and Pipe Network
The pit and pipe network has been included in the TUFLOW model as a 1D network. The pits enable the
transfer of flows from the 2D domain to the 1D pipes below the ground. The pipes carry flows to the outlet
where it discharges to the 2D domain. The pit and pipe data received from Council could not be used
directly in the TUFLOW model. Each branch of the network was analysed and the following modifications
were made to the GIS layers to enable an adequate representation of the network in TUFLOW:
Pipes smaller than 450 mm in diameter were removed (including pits connected to these
pipes).
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