The overall objective of this study is to develop a Floodplain Risk Management Study where management issues are assessed, management options are investigated and recommendations are made. Thereafter a Floodplain Risk Management Plan detailing how flood prone land within the study area is to be managed can be completed. The objectives of the Flood Risk Management Study are to:,

The primary objective of the Lower Ourimbah Creek Floodplain Risk Management Study Review is to determine appropriate floodplain management measures for the preparation of a cost-effective Floodplain Risk Management Plan for the study area. The study addresses flooding caused by runoff in the Ourimbah Creek and its tributaries and does not address flooding caused by elevated water levels in Tuggerah Lakes independent of river flooding. Floodplain management for Tuggerah Lakes flooding is to be addressed in a separate study, currently under development.

Conclusions The objective of the study was to undertake a detailed flood study of the Lake Wyangan catchment and establish models as necessary for design flood level prediction. Through the undertaking of the flood study it has been found that during flood events the majority of the catchment runoff flows to Tharbogang Swamp rather than Lake Wyangan, as had previously been assumed. Historically there has been little response of Lake Wyangan water levels to rainfall events within the catchment, with only the March 1989 event producing a significant response. The limited response in Lake Wyangan is due to a number of factors: It has a relatively small catchment area of around 100km2, including diverted catchment runoff through the Lake View Drain (Lake Wyangan’s natural catchment is around 75km2); The calibration process found the catchment to indicate a high initial rainfall loss for the events considered. A large amount of rainfall (>60mm) is required before any catchment runoff is generated and a response in the lake can be observed; and A proportion of the catchment runoff volume is retained in temporary flood storages in the catchment, rather than further contributing to the flood storage in the lake. Being a volume-driven closed-catchment system with no natural outlet, flood levels in Lake Wyangan and Tharbogang Swamp are directly related to the catchment runoff volume generated by any given flood event. The high rainfall losses generate relatively small effective rainfall depths and the flood levels are therefore highly sensitive to changes in the adopted initial loss value. The calibration process found an initial loss value of around 60mm to be appropriate for the events considered. However, due to the characteristics of the available design rainfall temporal pattern, this loss value was reduced for design purposes. Tharbogang Swamp has a much larger catchment area than Lake Wyangan and therefore shows a much greater flood response. Unfortunately there has been no history of flood level recording in Tharbogang Swamp to compare to the modelled flood response. The study also identified a number of local overland flow paths which impact of the planned development areas of Council’s Growth Strategy 2030. It is important that these flow paths are taken into consideration during the stages of development planning. The flood study will form the basis for the subsequent floodplain risk management activities, being the next stage of the floodplain risk management process. The key locations to consider during this process have been identified as: Locations where there is potential for cross-catchment flow transfer from the Tharbogang Swamp catchment into Lake Wyangan (potential changes to the existing flow distribution may result from future on-ground works in these localities) ; and Locations where the floodways occur within the proposed development areas of the Giffith Growth Strategy 2030.

Study Objectives The key objective of this Flood Study is to develop computational models that can be used as the basis for a Floodplain Risk Management Study and Plan for the study area. The study is also to assist SCC to undertake flood-related planning decisions for existing and future developments. The study covers the Lake Wollumboola catchment and the Culburra Beach village catchment. The components of the study were to: collate available historical flood-related data; analyse of historical rainfall and lake level data; undertake a community consultation program; develop numerical models of flooding in the catchment and calibrate them to historical data; determine the flood behaviour including design flood levels, velocities and flood extents within the catchment; to determine provisional residential flood planning levels and flood planning area; to assess the sensitivity of flood behaviour to potential climate change effects such as Lake Wollumboola Flood Study WMAwater 150917_LakeWollumboola_FloodStudy_Final:24 September 2015 5 increases in rainfall intensities and sea level rise; and to assess the floodplain categories in accordance with Council policy and undertake provisional hazard mapping.

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.

Conclusions: The objective of the study was to undertake a detailed flood study of the Main Drain J catchment and establish models as necessary for design flood level prediction. This included the assessment of inputs to the catchment from Mirrool Creek. In completing the flood study, the following activities were undertaken:,

The purpose of a floodplain study is to establish the 100-year floodplain limits within or near a development in order to preserve the natural resources within the 100-year floodplain, to protect property and persons, and to apply a unified, comprehensive approach to floodplain management. Update Frequency - Daily

The main objective of this study (in two parts) has been to determine water levels in Brisbane Water for the full range of flood and ocean events that can occur due to the various natural physical processes, taking joint occurrence issues into account to some extent. The flooding behaviour can be influenced, either separately, or by a combination of, catchment rainfall runoff flooding, rainfall directly onto Brisbane Water, elevated ocean levels, local winds and, to a minor extent, the condition of the ocean entrance channel near Ettalong. The outcomes from this study include: -,

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:,

This report documents the Lake Wyangan Floodplain Risk Management Study and Plan which investigates and presents a flood risk management strategy for the catchment. The study identifies the existing flooding characteristics and canvasses various measures to mitigate the effects of flooding. The end product is the Floodplain Management Plan, which describes how flood liable lands within Lake Wyangan are to be managed in the future.