This report comprises an overview of the work that has been undertaken by WMAwater on the Manly Lagoon Floodplain Risk Management Study and Plan. It builds on prior stage reports and, in accordance with the Brief, it additionally includes a discussion of: • hydraulic and hazard categorisation; • future development scenarios; • review of climate change; • flood damages assessment; and • emergency management.

Narrabeen Lagoon Floodplain Risk Management Study and Plan 2019 - Reports

Processed results include: depth, level, velocity, VxD, hazard, hydraulic categories, FPA, extents, emergency response categories, and climate change

Flood study centres around the opening of Cockrone Lagoon to the ocean when the water level exceeds the let-out-level of RL2.476m AHD. The policy is aimed at minimising the flooding of properties adjacent to the lagoon. The investigation process used in this flood study was: collection of available data assessment of available data overview of lagoon behaviour assessment of coastal processes hydrologic modelling of the catchment to determine flood inflows, and hydraulic modelling of the lagoon to assess flood levels from flood inflows

Hydraulic Model (MIKE-11) - Inputs and Outputs

Data contains: Model files for design runs; Model files for sensitivity runs; Model files for blockage assessment;

The Post 2022 Event Flood Behaviour Analysis - Brunswick River aims to understand the areas impacted by the recent 2022 flood event and determin the current approved flood model's ability to replicate the 2022 event. The study area includes the townships of Mullumbimby, Brunswick Heads, Ocean Shores, and villages of New Brighton, South Golden Beach and Billinudgel. The study area covers an area of approximately 230 square kilometres, and includes diverse environments, generally comprising of dense vegetation in the hinterlands and coastal villages to the east of the catchment. The Post 2022 Event Flood Behaviour Analysis of the Brunswick River involved a review of the hydrological and hydraulic models, and IFD estimates. Flood Frequency Analysis and Regional Flood Frequency Estimation methods were undertaken to assess the model perfomance. A damage assessment was undertaken to determine the cost of damage and the degree of disruption to the community caused duing flooding event.

Hilltops Council (Council) commissioned the Floodplain Risk Management Study and Plan for the township of Boorowa. The overall 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, consider options for the management of flood affected land and to develop a Floodplain Risk Management Plan (FRMP) which: i) Proposes modifications to existing Council policies to ensure that the development of flood affected land is undertaken so as to be compatible with the flood hazard and risk. ii) Proposes Flood Planning Levels for the various land uses in the floodplain. iii) Sets out the recommended program of works and measures aimed at reducing over time, the social, environmental and economic impacts of flooding. iv) Provides a program for implementation of the proposed works and measures. The FRMS focuses on Main Stream Flooding from the Boorowa River, Ryans Creek and Ryans Tributary, as well as two major un-named tributaries, Minor Tributary Flooding caused by high flows in the minor un-named tributaries which drain to the aforementioned watercourses, and Major Overland Flow areas which occur in the urbanised parts of Boorowa and its immediate surrounds.

Hilltops Council (Council) commissioned the Floodplain Risk Management Study and Plan for the township of Boorowa. The overall 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, consider options for the management of flood affected land and to develop a Floodplain Risk Management Plan (FRMP) which: i) Proposes modifications to existing Council policies to ensure that the development of flood affected land is undertaken so as to be compatible with the flood hazard and risk. ii) Proposes Flood Planning Levels for the various land uses in the floodplain. iii) Sets out the recommended program of works and measures aimed at reducing over time, the social, environmental and economic impacts of flooding. iv) Provides a program for implementation of the proposed works and measures. The FRMS focuses on Main Stream Flooding from the Boorowa River, Ryans Creek and Ryans Tributary, as well as two major un-named tributaries, Minor Tributary Flooding caused by high flows in the minor un-named tributaries which drain to the aforementioned watercourses, and Major Overland Flow areas which occur in the urbanised parts of Boorowa and its immediate surrounds.