breadcrumb banner
Floodplain Risk Management Study and Plan

Combined Catchments of Whartons, Collins and Farrahars Creeks, Bellambi Gully and Bellambi Lake Floodplain Risk Management Study and Plan

SUMMARY

S1 Study Objectives

Wollongong City Council (WCC) commissioned the preparation of the Floodplain Risk Management Study and Plan for the combined catchments of Whartons, Collins and Farrahars Creeks, Bellambi Gully and Bellambi Lake. The objectives of the Floodplain Risk Management Study (FRMS) were to assess the impacts of flooding, review existing Council policies as they relate to development of land in flood liable areas within the study area, consider options for the management of flood affected land and to develop a draft Floodplain Risk Management Plan (FRMP) which:

i) Proposes modifications to existing Council policies to ensure that the development of flood affected land within the study area is undertaken so as to be compatible with the flood hazard and risk.

ii) Sets out the recommended program of works and measures aimed at reducing over time, the social, environmental and economic impacts of flooding.

iii) Provides a program for implementation of the proposed works and measures.

The FRMS focuses on local catchment (main stream only) and coastal flood behaviour in the study area. The potential impacts of future climate change on flood behaviour, as a result of increased sea levels and rainfall intensities, are also assessed.

S2 Summary of Flood Impacts

The study area comprises the urbanised portion of Whartons, Collins and Farrahars Creeks, Bellambi Gully and Bellambi Lake. Flooding in these catchments is “flash flooding” in nature, with flood levels peaking within an hour of the commencement of heavy rainfall. Figure S1 (3 Sheets) shows indicative depths of inundation in the study area for the 100 year average recurrence interval (ARI) flood, together with the extent of the Probable Maximum Flood (PMF). Damaging flooding will occur in the study area even at the 5 year ARI level, albeit with relatively shallow depths of inundation, and progressively increase with increasing ARI as shown in Table S1 over. Blockage of hydraulic structures has the potential to significantly increase flood hazard and damages in the study area. For example, there are 245 existing residences that could experience above-floor flooding should hydraulic structures become blocked by debris during a flood with an ARI of 100 years. Blockage of hydraulic structures has the potential to increase total flood damages in the study area at the 100 year ARI level from about $34 Million to a maximum of about $59 Million.

Additional Information

Field Value
Title Combined Catchments of Whartons, Collins and Farrahars Creeks, Bellambi Gully and Bellambi Lake Floodplain Risk Management Study and Plan
Publication Date June 1, 2014
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Tiles by MapBox
Council/LGA Wollongong City Council
Author/ Prepared by Lyall and Associates Consulting Water Engineers
Publish date May 10, 2017
Update date July 7, 2017
River Basin 214 - Wollongong
Place Name Wollongong
Approval State Approved
Submitted for approval July 7, 2017
Submitted by Jamin Hudson
Approved July 27, 2017
Approved by plattns
Data Comment

Report has Design Flood Modelling, Design Flood Behaviour and Hydraulic Modelling.

Identifier ec575b91-d149-4afa-90e6-42f425558b18