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Flood study

Wollongong City Flood Study

Contains Volume 1 - Main Report and Volume 2 - Maps. Contains data relating to Flood Extents, Flood Hazard Zones, Flood Risk Precincts and Hydraulic Categorisation. Files supplied in MAP INFO format.

EXECUTIVE SUMMARY

BACKGROUND

The Wollongong City catchment area includes the suburbs of Wollongong (south of Crown Street), Coniston, and northern Port Kembla, and drains towards Wollongong Golf Course and JJ Kelly Park, ultimately discharging into Port Kembla Inner Harbour via the Gurungaty Waterway and Tom Thumb Lagoon. There have been several recorded instances of floodproducing storms in the catchment, including March 1978, March 1983, December 1990, March 1995, March 2011 and February 2012.

A previous Flood Study of the lower catchment area, including modelling of open channel areas of Wollongong Golf Course and JJ Kelly Park, was undertaken in 1990 by GHD on behalf of the Water Board (Reference 3). The study did not estimate flood behaviour in residential areas of the catchment. The area was also included in a study on the August 1998 storms that affected the greater Wollongong region (Reference 4), which found that rainfalls near the coast at Wollongong City were far less severe than those that fell higher on the Illawarra Escarpment.

The present Flood Study has been commissioned by Wollongong City Council (WCC), with funding assistance administered by the NSW Office of Environment and Heritage (OEH). This study considers flooding in the entire Wollongong City catchment from local storm runoff, as well as backwater flooding from tidal influences in Port Kembla Inner Harbour. The key objective of this Flood Study is to develop a suitable hydraulic model that can be used as the basis for a Floodplain Risk Management Plan for the study area, which will assist Wollongong City Council to undertake flood-related planning decisions for existing and future developments. Previous hydraulic modelling of the study area was limited in extent, and did not estimate flood levels or flows in residential areas of the catchment. The primary objectives of the study are:

  • to determine the flood behaviour including design flood levels and velocities over the full range of flooding up to and including the PMF from storm runoff in the Wollongong City Catchment and from tidal influences;
  • to provide a model that can establish the effects on flood behaviour of future development;
  • to assess the sensitivity of flood behaviour to potential climate change effects such as increases in rainfall intensities and sea level rise; and
  • to assess the provisional hydraulic categories and undertake mapping of provisional hazard, preliminary emergency response planning classifications, and preliminary flood planning extent areas. This report details the results and findings of the Flood Study investigations. The key elements include: Wollongong City Flood Study WMAwater 111022:WollongongCBD_FloodStudy_Final:17 April 2013 iii
  • a summary of available historical flood related data;
  • establishment and validation of the hydrologic and hydraulic models;
  • sensitivity analysis of the model results to variation of input parameters;
  • potential implications of climate change projection; and
  • the estimation of design flood behaviour for existing catchment conditions.

Additional Information

Field Value
Title Wollongong City Flood Study
Publication Date 1 April 2013
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Author/ Prepared by WMA Water
Publish date 6 July 2017
Update date 15 July 2020
River Basin 214 - Wollongong
Place Name Wollongong
Approval State Approved
Submitted for approval 7 July 2017
Submitted by Jamin Hudson
Approved 16 July 2020
Approved by ses-sysadmin
Data Comment

Contains Design Flood Modeling, Flood Planning Area and post processed results.

Identifier e678cbb2-b842-498d-93f4-2774b5b58a6f