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.

Flood Study August 2010

Zip file includes Lake Macquarie Flood Study Part 1 – Design Lake Water Levels and Wave Climate Report MHL682 January 1998 Lake Macquarie Flood Study Part 2 – Foreshore Flooding Report MHL715 April 1998.

Spatial data only- creekline, culvert locations, RAFTS layout, sub catchments, SOBEK x-sections, catchment boundary.

In view of the increasing catchment development and the need to accurately define the flood problem, Lake Macquarie City Council engaged Webb, McKeown & Associates, to undertake a Flood Study. The primary objectives of this Flood Study are: • to define the flood behaviour of the North Creek catchment by producing information on flood levels, velocities and flows for a range of design flood events under existing catchment and floodplain conditions, • to assess the hydraulic categories and undertake provisional flood hazard mapping, • to assess the extent of the flood problem by undertaking a damages assessment, • to formulate suitable hydrologic/hydraulic models that can be used in a subsequent Floodplain Risk Management Study to assess various floodplain management measures, including the effects of further development. This report details the results and findings of the Flood Study investigations. The key elements include: • a summary of available data, • reasons for the choice of hydrologic and hydraulic models, • calibration of these models, • establishment of design flood behaviour, • flood damages assessment. The Flood Study does not consider flooding from local drainage which may result from inadequate urban drainage provisions.

Tuflow input data. Contains data for ARR1987 and ARR2016

Map displaying the extents of flood studies, floodplain risk management studies/plans, and the years of their completion.

Floodplain Management Plan Report and figures. This Plan provides the basis for the future management of flood liable lands adjacent to the lake in the Lake Macquarie City Council area. The Plan was developed from the Lake Macquarie Flood Study (Part 1 - January 1998 and Part 2 - April 1998) and the Lake Macquarie Floodplain Management Study (August 2000). The Lake Macquarie Flood Study determined design flood levels for the 1%, 2% and 5% AEP floods and an Extreme flood event. It examined the still water level and also the effect of wave runup along the foreshore. The design events represent floods which have a certain probability of occurrence. The “1% AEP” or “1 in 100" flood has a 1 in 100 chance of being equalled or exceeded in any year. On a LONG TERM average it will happen once in every 100 years, but it is wrong to think it can only happen once in a century. Because floods are random events there is still a 1 in 100 chance of such a flood occurring next year no matter what happens this year.

Final Report PDF

Report only