Objectives The objective of this Study is to define the nature of the existing flood behaviour in the Burradoo BU2 catchment. To achieve the objective, the following tasks were undertaken:,

The activities comprising the present investigation included:,

The Flood Study had three main components:,

Volume 1 Report This flood study has been undertaken to determine the flood behaviour in the catchment due to local storm runoff for the 0.5% Annual Exceedance Probability (AEP), 1% AEP, 2% AEP, 5% AEP, 10% AEP, 20% AEP, 50% AEP and 100% AEP flood events and the Probable Maximum Flood (PMF). In accordance with its objectives, the study has determined the nature and extent of flooding through the estimation of design flood flows, levels and velocities. Flood impacts due to storm events in the Brisbane Water estuary are detailed in the Brisbane Water Foreshore Flood Study (2009). In undertaking the flood study, a hydrologic-hydraulic computer model of the major channels and floodplain within the catchment was established and verified against historical flood event observations. The hydraulic model was then used with design rainfall conditions to simulate design flood behaviour in the catchment. The study has defined Provisional Flood Hazard and Hydraulic Categories for the flood affected areas. The objective of this Study is to define the nature of the existing flood behaviour due to local runoff only in the Davistown catchment. To achieve the objectives, the following tasks were undertaken:,

The key objective of this Flood Study is to develop a suitable hydrologic/hydraulic model that can project flood and permanent inundation water levels in Lake Macquarie from rainfall, sea level rise and storm surge. These results will be used by Lake Macquarie City Council, in consultation with the community of Lake Macquarie City, to manage flood and permanent inundation risks to low lying land around the Lake Macquarie waterway. The key stages in the process are: Undertaken a comprehensive review of the 1998 Lake Macquarie Flood Study (Part 1 – Reference 1) and develop suitable hydrologic/hydraulic models to define flood behaviour over the full range of design events for existing catchment conditions, Use the hydrologic/hydraulic models to assess various climate change scenarios, including application of the NSW Government’s sea level rise benchmarks, Assess the potential increase in storm surge as a result of climate change and its impact on elevated ocean levels, Review the potential impact of climate change on the local wind/wave climate as this affects the extent of wave runup on the foreshore, Assess the hydraulic and hazard categories for existing and climate change conditions. This report details the results and findings of the above investigations. The key elements include: a summary of available historical flood related data, establishment of the hydrologic and hydraulic models, calibration of the hydrologic and hydraulic models, definition of the design flood behaviour for existing catchment conditions, sensitivity analysis of the design flood behaviour, assessment of the impacts of climate change on the still water and wave runup water levels re-definition of the flood extent and hydraulic and hazard categories mapping for existing and climate change conditions. A Flood Study is a technical document and not easily understood by the general public. A glossary of flood related terms is provided in Appendix A to assist. If more explanation of terms or a better understanding of the approach is required, type “NSW Government Floodplain Development Manual” into an internet search engine and you will be directed to the NSW Government web site which provides a copy of this manual and further explanation. Flood levels given in this report relate only to the water level with the lake itself. Design water levels in the creek systems entering the lake (Cockle Creek, Dora Creek etc.) will be higher than those shown for the lake.

The study investigates flood behaviour throughout the Gwawley Bay catchment. This includes the analysis of:,

Objectives Sutherland Shire Council engaged Webb, McKeown & Associates to prepare the Kurnell Township Flood Study, utilising current technology and data. The information and results obtained from the study will be used in the preparation of the Floodplain Risk Management Study and Plan. The specific objectives of the Kurnell Township Flood Study are to:,

The Raymond Terrace Flood Study has been prepared for Port Stephens Council (Council) to define the existing flood behaviour in the western Raymond Terrace catchments and establish the basis for subsequent floodplain management activities. The study will also assist Council in considering future upgrades to the drainage network and flood relief pump capacity to the Hunter River. This project has been conducted under the State Assisted Floodplain Management Program and received State financial support.

This report has been prepared for Warringah Council to define the nature and extent of flood in the Dee Why South Catchment. Flood modelling was completed to define flood behaviour for a range of storm events from 1 year Average Recurrence Interval (ARI) to Probable Maximum Flood (PMF). The modelling shows that significant flows are conveyed in the piped drainage network and overland through roads and properties. Generally the main overland flowpath starts from several branches at Alfred Street to Beverley Job Park. Flows in the open channel at Victor Road and Redman Road combine with overland flows from Mooramba Road, Fisher Road, and Pittwater Road at the intersection of Redman Road and Pittwater Road. Overland flows are then conveyed along several roads and properties to Dee Why Lagoon as well as in the open channels between Pacific Parade / Oaks Avenue and downstream of Dee Why Parade. In a 1% AEP event, the results show that ponding of runoff occurs at several locations with restricted outlet capacity. High pedestrian areas in Dee Why CBD also experience overland flow inundation, particularly along Redman Road, Pittwater Road, Oaks Avenue and Howard Avenue. In a 1% AEP event floodway and high provisional hazard flow conditions along the open channels, on roads, and some properties including in the Dee Why CBD. A series of climate change scenarios were also modelled to evaluate potential impacts from elevated sea levels and increased rainfall intensity. Results showed that the modelled increases to Lagoon level have an impact to flood inundation of low-lying land near the Lagoon. Most properties within the Dee Why South catchment do not show a significant change in inundation extent for the modelled scenarios. Modelled increases in rainfall intensity showed a rise in peak water levels across the catchment, particularly in trapped low points such as on Sturdee Parade and Alfred Street. Council applies land use planning and development controls to manage development within flood prone areas. The flood result and mapping provided in the document will assist Council with future land use planning, development controls and floodplain risk management. The next stage of the floodplain risk management process following the adoption of the Flood Study is the Floodplain Risk Management Study and Plan. This next stage will investigate various floodplain risk management measures and prioritise these measures for implementation.

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