Powells Creek Flood Study
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inflows but was adopted as it allows more efficient and flexible incorporation of the flow hydrographs into TUFLOW. The 2016 study provided significantly improved definition of flood behaviour across the floodplain, including both overland and mainstream flooding. Maps were produced showing information on flood levels, depths, extents, velocities and flows for a range of flood events up to the probable maximum flood (PMF) events and included flood emergency response classification of communities and the sensitivity of flood behaviour to changes in flood producing rainfall events due to climate change (rainfall increase and sea level rise).
A comparison of the results from this study and the present study along the main channel of Powells Creek is provided in Table 31.
2.2.3.
2015 Concord West Precinct Master Plan Flood Study (Reference 3)
This study was initiated by the City of Canada Bay and several landowners, at the time of the proposed naturalisation of the lower parts of Powells Creek by SWC and proposed rezoning of several industrial lots. Jacobs were engaged to undertake a flood study and prepare a concept design for flood mitigation measures for the Master Plan. This study has not been adopted by the City of Canada Bay Council. The study area was defined as: • Powells Creek from approximately Parramatta Road to Homebush Bay. • •
Saleyards Creek from M4 Motorway to Powells Creek; and Strathfield Creek from 100m upstream of Ismay Avenue to Powells Creek.
The following were allowed for in the study, based on the design information available at the time, but have since been completed: • North Strathfield Rail Underpass Project (NSRUP). •
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Sydney Water Powells Creek naturalisation. Canada Bay Primary School Victoria Avenue Concord West. Filling of Powells Creek Reserve North Field; and Reconstruction of the west end of Victoria Avenue including drainage upgrade.
Several flood mitigation options were identified and assessed to mitigate flood impacts with the Master Plan. These options have not been discussed in this present report as it is a Flood Study and is therefore only concerned with determining design flood conditions based on the existing conditions at this time (2021). Mitigation options will be considered and investigated in any subsequent Floodplain Risk Management Study and Plan (refer Foreword and Section 1.5). The study relied upon upstream inflow hydrographs on Powells Creek based on ILSAX from the 1998 Powells Creek Flood Study (Reference 1) and local inflow hydrographs from a DRAINS model incorporating the NSRUP works. It was not possible to undertake an independent calibration of the hydrologic model and the hydraulic model was only calibrated to the one available data point from the 10 February 1990 event (data point taken from Reference 1). The results from comparison of recorded overland peak depths with model depths are shown in Table 2.
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