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Flood study

Review of Hewitts Creek Flood Study Final Report

EXECUTIVE SUMMARY

Introduction

The review of Hewitts Creek Flood Study has been prepared for Wollongong City Council (Council) to define the existing flood behaviour in the Hewitts Creek study area and consider the influence of potential climate change on future flood behaviour.

The review updates the previous Hewitts Creek Flood Study (Forbes Rigby Pty Ltd., 2002a), to account for the various recent changes within the study area and take advantage of innovations and improvements in computer flood modelling. The study provides a holistic assessment of historic, current and future flood risk and establishes the basis for the subsequent Floodplain Risk Management Study and Plan.

Flood risk has been assessed through the establishment of appropriate numerical models. The study has produced information on flood flows, velocities, levels and extents for a range of flood event magnitudes under existing catchment and floodplain conditions and considering the influence of potential climate change on future flood behaviour.

Specifically, the study incorporates:

  • Compilation and review of existing information pertinent to the study, and acquisition of additional data including survey as required;
  • A community consultation and participation program to identify local flooding concerns, collect information on historical flood behaviour and engage the community in the on-going floodplain management process;
  • Development and calibration of appropriate hydrologic and hydraulic models;
  • Determination of design flood conditions for a range of design events - including the 20% Annual Exceedance Probability (AEP), 10% AEP, 5% AEP, 2% AEP, 1% AEP, 0.5% AEP, 0.2% AEP and Probable Maximum Flood (PMF);
  • Examination of potential impact of climate change using the latest guidelines for the 1% AEP design event; and
  • Presentation of study methodology, results and findings in a comprehensive report incorporating detailed flood mapping.

Catchment Description

The Hewitts Creek study area includes the catchments of Slacky, Tramway, Woodlands, Hewitts and Thomas Gibson Creeks. The combined catchments drain an area of approximately 8.1km2 and extend from the Illawarra Escarpment in the west to Thirroul Beach, McCauley’s Beach and Bulli Beach in the east, where they discharge into the Tasman Sea.

Additional Information

Field Value
Title Review of Hewitts Creek Flood Study Final Report
Publication Date 1 August 2015
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Council/LGA Wollongong City Council
Author/ Prepared by BMT WBM
Publish date 20 June 2017
Update date 26 July 2017
Place Name Thirroul, Bulli
Approval State Approved
Submitted for approval 7 July 2017
Submitted by SES System Administrator
Approved 27 July 2017
Approved by plattns
Data Comment

Report only; no other data.

Identifier 5c71b02f-22eb-4d40-b0b8-337beb1532b5