13. ACKNOWLEDGEMENTS

Table 28: Results of Blockage Variation – Change in Peak Depth (m)

ID Location

H01 Pedestrian Bridge 2 H02 Pedestrian Bridge 1

Peak Flood Depth 5% AEP Difference with 5% AEP (m)

Decrease blockage by 25% Increase blockage by 25%

Peak Flood Depth 1% AEP Difference with 1% AEP (m)

Decrease blockage by 25%

Increase blockage by 25%

0.63 0.00 0.00 0.71 -0.01 0.00 1.04 0.00 0.00 1.11 -0.01 0.00

H03 Front of community Centre 0.20 0.00 0.00 0.22 0.00 0.00 H04 Railway underpass 2 East side 0.12 0.00 0.00 0.16 0.00 0.00 H05 Railway underpass east side 0.47 0.00 0.00 0.68 0.02 0.00 H06 Railway underpass west Side 0.57 0.00 0.00 0.72 0.01 0.00 H07 7 Concord Avenue low point 0.44 0.01 -0.02 0.55 0.02 -0.02 H08 George Street low point near soccer field 0.81 0.10 -0.21 1.08 0.14 -0.18 H09 Powells Creek @ Argonne Street 0.19 0.00 0.00 0.35 -0.01 -0.01 H10 Powells Creek @ Pomeroy Bridge 0.20 0.01 -0.01 0.29 0.00 -0.01 H11 Powells Creek @ Allen Street 1.92 0.01 -0.01 2.09 0.00 -0.01 H12 Powells Creek @ Brussels Street 0.40 0.01 0.00 0.56 -0.01 -0.01 H13 Powells Creek @ Warsaw Street 0.75 0.02 0.00 0.92 -0.02 -0.01

An additional blockage scenario investigated was the effect of 100% blockage of the culverts under Homebush Bay Drive with the results for the 1% AEP event shown on Figure 25. The figure shows that flood levels will rise by up to 0.7m. The two main areas are: • between Victoria Avenue to the south and Concord Avenue to the north and • the area termed Village Green surrounded by Settlers Boulevard.

9.3.3. Sea Level Rise Variations

The sea level rise scenarios were found to have an insignificant effect on peak flood levels, except in the most downstream reaches of the catchment. The open channels upstream of Underwood Road and Pomeroy Street have channel inverts of 0.35 m AHD and 0.45 m AHD (respectively) and were therefore tidally affected under current tidal conditions. Under sea level rise conditions, these locations were found to have increased peak flood levels. At Pomeroy Street the increase in peak level reduces to less than 0.1m with a 0.9m increase. The attenuation of sea level rise impacts is because of the retarding effect of the downstream mangroves and the restrictive effect of bridge structures crossing the open channel.