Powells Creek Flood Study
and a 0.9 m rise by the year 2100.
9.3.
Results
The sensitivity scenario results were compared to the 1% AEP rainfall event and a summary of peak flood level and peak flow differences at various locations are provided in the sections below.
9.3.1. Roughness Variations Overall peak flood level results were shown to be relatively insensitive to variations in the roughness parameter. Generally, these results were found to be within ± 0.1 m. Table 27: Results of Roughness Variation – Change in Peak Depth (m) ID
H01 H02 H03 H04 H05 H06 H07 H08 H09 H10 H11 H12 H13
Location
Peak Flood Depth 5% AEP
Pedestrian Bridge 2 Pedestrian Bridge 1 Front of community Centre Railway underpass 2 East side Railway underpass east side Railway underpass west Side 7 Concord Avenue low point George Street low point near soccer field Powells Creek @ Argonne Street Powells Creek @ Pomeroy Bridge Powells Creek @ Allen Street Powells Creek @ Brussels Street Powells Creek @ Warsaw Street
Difference with 5% AEP (m)
Peak Flood Depth 1% AEP
Difference with 1% AEP (m)
0.63 1.04 0.20 0.12 0.47 0.57 0.44
Decrease roughness by 25% -0.01 -0.02 0.00 -0.01 0.00 -0.01 0.00
Increase roughness by 25% 0.00 0.01 0.00 0.01 -0.01 0.01 0.00
0.81 0.19
0.12 0.00
-0.01 -0.01
1.08 0.35
0.08 0.00
0.03 -0.01
0.20 1.92 0.40 0.75
0.00 0.00 0.00 0.00
0.00 -0.01 -0.01 -0.01
0.29 2.09 0.56 0.92
-0.02 0.00 0.00 -0.01
0.01 0.00 0.00 0.00
0.71 1.11 0.22 0.16 0.68 0.72 0.55
Decrease roughness by 25% -0.02 -0.02 0.00 -0.01 0.02 -0.01 0.00
Increase roughness by 25% 0.01 0.01 0.00 0.01 -0.02 0.01 0.00
9.3.2. Blockage Variations Peak flood level results were found to be relatively insensitive to blockage of pipes; although generally peak flood levels increased in the upstream areas and decreased in the downstream areas (due to the retarding effect in the upstream areas).
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