Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 38
Narellan Creek Catchment
Flood Study
Vegetation
Miscellaneous
Table 7 TUFLOW Roughness Coefficients
Material Description
Depth1
(m)
Roughness1
Depth2
(m)
Roughness2
Default (Unassigned Materials)
All depths
0.035
Buildings
0.15
0.03
0.3
1.0
Energy Dissipation Structures
0.3
0.06
0.31
0.02
Concrete
All depths
0.015
Roads
All depths
0.020
Shrubs/Grass
All depths
0.035
Trees
0.5
0.035
0.51
0.08
Cumberland Plain Woodland
0.4
0.07
2
0.07
River-flat Eucalypt Forest
0.4
0.05
2
0.07
Revegetated Riverflat Eucalypt Forest
0.4
0.05
2
0.06
Swamp Oak Floodplain Forest
0.4
0.035
2
0.06
Revegetated Swamp Oak Floodplain Forest
0.4
0.1
2
0.07
Sedgeland
0.2
0.06
1
0.06
Revegetated Reedland
0.4
0.05
2
0.025
Revegetated Mixed Native
0.4
0.09
2
0.08
Slashed Grassland
0.05
0.075
0.25
0.03
Parkland with Trees
0.05
0.075
0.25
0.04
Grazed Paddocks
0.05
0.075
0.25
0.02
Grazed Paddocks with Scattered Vegetation
0.05
0.075
0.25
0.03
Open Grass Land with Coarse Grass
0.05
0.075
0.25
0.035
All depths
0.04
Concrete Channels
0.02
0.02
0.1
0.011
Sandy Channel
0.05
0.035
0.25
0.013
Gravel channel
0.1
0.08
0.25
0.04
Vegetated Creek with Light Vegetation
0.3
0.05
1.5
0.035
Vegetated Creek with Medium Obstruction
0.5
0.10
2.5
0.075
Vegetated Creek with High Obstruction
0.5
0.10
2.5
0.095
Reedy Creek
0.5
0.08
1.5
0.05
Vegetated Overbank Flowpath
0.5
0.15
1.5
0.075
Rocky Channel
0.5
0.08
1.5
0.04
Grassed Channel with Short Grass
0.05
0.075
0.25
0.02
Grassed Channel with Coarse Grass
0.05
0.075
0.25
0.035
Watercourse
Water body
The lower part (i.e., the area between the ground surface and the floor level) of each
residential building was represented as a complete flow obstruction. This is shown
conceptually in Plate 9. A 0.15 metre height was selected as being representative for most
residential dwellings (reflecting a single step up to the front door). A 0.15 metre height is
also consistent with minimum floor level requirements set out in the National Construction
Code.
Once the water level exceeds the floor level of each building, it was allowed to
