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.

Preliminary Mitigation Option Assessment: Options were reviewed for the 12 hotspots. Over 20 preliminary mitigation options were modelled.

Targeted community consultation: targeted community consultation in identified hotspot areas was carried out from 29 July to 10 August 2025. Consultation submissions, questions and feedback are currently under review.

Detailed Assessment of Mitigation Options: Once the consultation is completed the 5 preferred mitigation options will be confirmed and will progress to detailed assessment. This includes simulation of the full suite of design events for the 5 preferred options and detailed multi-criteria assessment, including benefit cost analysis.

Public Exhibition of the draft FRMS&P: Following Council approval, the draft report, including the study, maps and options will be on public exhibition at the end of 2025.

The Flood Risk Management Study and Plan will have three stages of consultation during the delivery of the project.

Stage 1 - June/July 2024: Complete

Stage 2 - July/August 2025: Flood mitigation consultation: Closed, submissions under review

Stage 3 - November/December: Public exhibition of the draft Flood Risk Management Study and Plan.

Stage 1 - Consultation

From June 11 to July 15, 2024 Waverley Council held a community consultation for part one of the Flood Risk Management Study and Plan.

Residents and property owners were asked to supply information, images and video relating to flooding they had experienced, either at their home or in other areas of Waverley. It was organised LGA-wide, focussing on the collection of data via Council’s Have Your Say (HYS) website.

Eighty-two submissions were received via the website, as well as 51 emails to the project team. Ten people attended Have Your Say face-to-face pop-ups across the LGA.

The Community Consultation Report can be found in the document library on this webpage.

Stage 2 – Consultation – closed. Submissions under review

From 15 July to August 10, 2025 Waverley Council held a targeted community consultation for 12 hotspot areas identified within the Waverley LGA Flood Study (BMT, 2021) and the Flood Risk Management Study and Plan.

Residents and property owners were invited to a webinar held on 29 & 30 July to which presented the background to the mitigation options proposed.

One on One sessions were also held on 5 & 6 August for community to provide specific feedback or ask questions in relation to the mitigation options.

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