Building on the completion of the Waverley Local Government Area (LGA) Flood Study, which was adopted in 2021, Waverley Council commenced the next step in the NSW Governments Flood Risk Management Framework in early 2024 - a Flood Risk Management Study and Plan (FRMS&P) for the Waverley LGA .

The objective of this project is to refine the model across the LGA and explore and recommend flood mitigation options to reduce or alleviate detrimental impacts of flooding where possible.

This project has two parts.

The Flood Risk Management Study

To incorporate community knowledge of flooding and undertake ground testing onsite to further refine the Waverley LGA flood study, improving its accuracy and the confidence that the community has in the flood planning maps. To develop and assess flood risk mitigation measures to reduce or alleviate existing and future flood risks in our community.

The Flood Risk Management Plan

This part of the project focuses on recommending and prioritising flood risk mitigation measures, including documenting the decisions made to manage flood risks into the future. A list of recommended measures and their priority are detailed in the plan including how they would be implemented and who is responsible.

The study and plan are being prepared by independent flood consultant Kellogg Brown & Root Pty Ltd (KBR) and urban planning consultant GLN Planning Pty Ltd. With joint support and funding from NSW Department of Climate Change, Energy, the Environment and Water (DCCEEW) under their Floodplain Management Program.

This project is separate to previous recently completed projects including the Waverley LGA Flood Study 2021 and the amendment to the Waverley Development Control Plan 2022.

Key activities completed to date:

Feedback integration: The consultant reviewed all community consultation feedback received during the community consultation June – July 2024 and incorporated relevant insights into the project’s technical work.

Model review and outputs: A comprehensive review and update of the flood model has been completed in line with flood modelling industry best practice and progress since the original study, including the required incorporation of updated climate change forecast data.

Updated flood mapping: Following the above updates, simulations have been re-run to produce updated flood maps. These maps will provide a clearer picture of expected flood extents and depths across the LGA.

Ground truthing inspections: To ensure the accuracy and reliability of the model and mapping the consultant team has conducted further on the ground inspections in key areas and verification of modelled flood extents against historical and recent rainfall events.

Baseline Flood Damages Assessment: Baseline flood damages assessment has been carried out for the entire suite of modelled design events.

Hot Spot Review: A review of the existing hot spots has been undertaken. The original 12 hot spots identified within the Waverley LGA Flood Study (BMT, 2021) have been maintained.

Flood Mitigation Option Assessment:  Options were reviewed for the 12 hotspots. Over 20 preliminary mitigation options were modelled and reviewed and were consolidated into 10 options upon further modelling and refinement. Five options were then recommended.

Targeted community consultation: Targeted community consultation on the proposed flood mitigation options was carried out from 29 July to 10 August 2025.

Detailed Assessment of Mitigation Options:  Following the outcome of the consultation, the five preferred mitigation options were confirmed and progressed to detailed assessment. This included simulation of the full suite of design events for the five preferred options and detailed multi-criteria assessment, including benefit cost analysis.

Draft FRMS Report: The work carried out to date was compiled into the draft Flood Risk Management Study (FRMS) report, including model updates, maps, mitigation options and measures and draft amended Development Control Plan (DCP) provisions.

Public Exhibition of the Draft FRMS: Following Council approval, we invited the community to provide feedback on the draft Waverley Flood Risk Management Study from 10 November - 8 December 2025. Eighty-two feedback submissions were received via the Have Your Say Website. Additional feedback via email was given and the HYS pop up also received feedback forms. A community consultation report will be produced and submitted to Council.

For planning purposes in Waverley, land is categorised into three food risk precincts:

• High: In this precinct there would be a significant risk of flood damages without compliance with flood related building and planning controls.

• Medium: In this precinct there would still be significant risk of flood damage, but these damages can be minimised by the application of appropriate development controls.

• Low: The risk of damages is low for most land uses. These Flood Risk Precincts represent the Flood Planning Area (FPA) for the purposes of planning controls in the Waverley Local Environmental Plan 2012 and Development Control Plan (DCP).

A comprehensive review and update of the flood model has been completed in line with flood modelling industry best practice and progress since the original Flood Study (2021) and subsequent amendment of the FPA and DCP in 2024. These updates included the required incorporation of updated climate change forecast data.

The latest flood model update has resulted in new, more accurate flood risk precinct mapping. In addition, existing planning controls in the DCP have been reviewed and a number of refinements are proposed. These amendments to the DCP can be viewed in Appendix C of the report and we are also seeking feedback on the proposed changes as part of the public exhibition of the Flood Risk Management Study.

Review the flood planning maps

Property owners identified as within the Flood Planning Area (FPA) who are planning redevelopment of their property may need to take some additional steps as part of the consent process. If you are identified on the maps and not planning to redevelop your property, there is nothing you are required to do.

The Flood Risk Precinct mapping is included on the Discover Waverley Planning Map (turn on the ‘Flood Planning Area’ layer).

You can review updated flood planning maps on the Discover Waverley online mapping system as follows:

1. Head to Discover Waverley Draft FRMS mapping page

2. Type in your address

3. Navigate to the ‘Flood Planning Area (Flood Risk Precincts)' layer in the legend on the right hand side.

4. Toggle on ‘Current Flood Planning Area’ and then toggle on ‘Updated Flood Planning Area’ layers to review the changes to your property through the updates to the flood model.

All other mapping related to different simulated rainfall events and their outputs can be reviewed in Appendix B of the Flood Risk Management Study.

Property owners identified as within the FPA who are planning redevelopment of their property may need to take some additional steps as part of the consent process. If you are identified on the maps and not planning to redevelop your property, there is nothing you are required to do.

Many parts of the LGA are unaffected by flood, so do not have a precinct marked on the map. Use the ‘Environment’ map and turn on the ‘Stormwater Pit & Pipe’ layer to view the public stormwater network.

For more information visit -https://www.waverley.nsw.gov.au/planning/development_applications/preparing_a_development_application/flood_planning

All other mapping related to different simulated rainfall events and their outputs can be reviewed in Appendix B of the Flood Risk Management Study.

All mapping is subjected to ongoing review, about every five to ten years. As these reviews take place, it is conceivable that changes to the mapping will occur, particularly if new flood level information or ground topography information becomes available.

In addition to the progress made on the FRMSP project, we’ve undertaken a number of other actions in parallel to reduce the impact of flooding within the community:

• In 2024, Council’s Assets team inspected approximately 20% of the assets (underground stormwater drains), with the focus on high-risk locations, where there are areas likely to be issues. The full network will be inspected and assessed by 2030
• High impact blockages and defects identified have been cleared and/or rectified already
• Resourcing needs have been identified and programmed to clear and rectify those remaining
• Our operations team have attended a large number of reactive incidents prior to and during storms to clear stormwater inlets, unblock drains and fix drainage issues across the network to improve flow and prevent flooding in real time
• We’ve undertaken minor stormwater capital improvement works across the LGA in problematic locations identified by residents to eliminate easily addressable flooding issues
• The capacity assessment and associated mapping will be provided for the community as part of the public exhibition of the draft Flood Risk Management Study & Plan report at the end of 2025.

The Flood Risk Management Study & Plan project focusses on identifying options to address the key / highest flood risk in the first instance. This feeds into Council’s applications for grant funding via the State Government to deliver large (expensive) stormwater infrastructure upgrades.

As an outcome of this project, we are able to identify what improvements can be delivered for smaller costs, which Council can deliver within its annual capital program to deliver flood benefits to the community.

Council is also undertaking a number of other actions in parallel to this work to reduce flood impacts across the local government area: inspecting the underground network to identify blockages and defects, rectifying these and undertaking smaller capital works.

2017

• Waverley Council started work on the Flood Study involving community feedback.
• The study was completed in accordance with the NSW Floodplain Development Manual and NSW Flood Prone Land Policy.

2020

• Study released for public exhibition.

2021

• Waverley Council adopted the Waverley LGA Flood Study.
• Council developed proposed amendments to Waverley Council’s Development Control Plan.

2022

• Proposed changes to Waverley Council’s Development Control Plan (DCP) exhibited.
• Low, medium and high-risk areas were identified.

2024

• Council engaged a consultant to start the Flood Flood Risk Management Study & Plan in February 2024.
• DCP amendment adopted in March 2024
• For more information on flood management see the flood management pages on Council's website.

Definition of a flood

Flooding results from relatively high stream flow that overtops the natural or artificial banks in any part of a stream, river, estuary, lake or dam, and/or local overland flowpaths associated with major drainage, and/or oceanic inundation resulting from super-elevated ocean levels.

What is mainstream flooding?

Mainstream flooding is water that overtops the natural or artificial banks in any part of a stream, river, estuary, lake or dam..

What is overland flooding?

Local overland flooding is inundation by local run-off on its way to a waterway, rather than overbank flow from a waterway. Overland flooding typically occurs during rainfall events where drainage systems reach capacity and excess water flows over land.

What is stormwater?

When rainwater comes into contact with surfaces such as roofs, paved areas such as roads, gardens, and other open spaces, it becomes stormwater.

Refer to FAQ in Document Library for more information

The draft report will be updated and amended accordingly and the plan will be refined before being finalised and submitted to Council for adoption in March 2026.