Project overview

The Flood Strategy - Port Philip and Westernport (2021-2031) establishes a key objective to ensure 'the right information is available at the right time to the people who need it'.

Through this flood mapping project, Council - in collaboration with Melbourne Water - will provide fit-for-purpose flood maps indicating the location, extent, depth and velocity of flooding under current and climate change conditions.

These flood maps can be used for land use planning, community awareness, and where practicable, flood mitigation works. The information will help manage flood risk to life, property, and community infrastructure and assist with protecting our significant floodplains.

Melbourne Water and Council have a duty of care to make flood information available to the community.

Melbourne Water is the manager for the Port Phillip and Westernport catchment area (not to be confused with water services, such as Greater Western Water).

The map below demonstrates the area this catchment covers, but for the Macedon Ranges specifically, local towns covered include Gisborne, New Gisborne, Macedon, Mount Macedon, Riddells Creek, Lancefield, Romsey and Darraweit Guim.

The project is being undertaken as a joint 50/50 cost-sharing arrangement for the modelling and mapping tasks, with Melbourne Water leading the project delivery.

The project's estimated cost (modelling and mapping components only) is $800,000 (exclusive of GST). Based on the agreement between Council and Melbourne Water in joint meetings, Council’s contribution is $400,000 (exclusive of GST). Council has allocated its share of funding over two financial years (FY 2023-24 and FY 2024-25).

This flood modelling study aims to create new flood information for Council using current rainfall and land development data, flood modelling standards (such as Australian Rainfall and Runoff 2019) and modelling methods. This data will enable Melbourne Water and Council to:

  1. give flood and development advice on land parcels (also identified as ‘properties’) affected by overland flow and/or riverine flooding along Melbourne Water and Council drains and waterways
  2. resolve land development issues, which may result in flood data being questioned at a Victorian Civil and Administrative Tribunal (VCAT) panel hearing
  3. support Planning Scheme Amendments (PSAs)
  4. inform capital works programming by identifying and quantifying flood risk
  5. allow VicSES to plan their emergency response strategies.

The flood mapping program will produce flood information consistently across the entire Melbourne Water municipal catchment. The outputs from this study are new flood depth, velocity and extent for Council from 20% Annual Exceedance Probability (AEP) up to and including 1% AEP + Climate Change. Data will be prepared in a manner that is ready for use. This includes:

  • demarcation of Melbourne Water and Council areas of responsibility
  • all flood overlays prepared using the 1% AEP + Climate Change modelling outputs
  • the ability to display (spatially) the change between the previous flood map and this current output.
    • Key information for communities from this flood modelling includes:
  • accessible maps that show the extent of flooding in the region
  • local flood guides for residents and business owners
  • information on how to prepare for a flood
  • information on future flooding risks related to climate change, including increased rainfall intensity, sea level rise and coastal flooding.

    • How you can have your say

    As part of this flood modelling project, an external consultant - with support from Council and Melbourne Water - is collecting information and data, and developing flood models.

    In this initial state of consultation, we are encouraging residents within the catchment area to share any their own experiences with localised flooding events including photos, recordings or other materials that can help us better understand the locations, dates, times, and depths.

    You can do this online through the submission form below, by making a written submission to our offices (see Contact Us details) or come along to one of our planned in-person engagement sessions and speak to us:

    Council's Gisborne Administration Centre (40 Robertson Street, Gisborne)– 5:30-7pm, 5 May 2025
    Romsey Hub (96-100 Main Street, Romsey) – 5:30-7pm, 6 May 2025
    Darraweit Guim Community Hall (1481 Bolinda-Darraweit Road, Darraweit Guim) – 5:30-7pm, 13 May 2025

    These sessions and this initial stage more broadly aim to raise awareness of the project, allow the community to ask questions, and seek input on past historical flood events (observed flood events).

    Feedback will be invited from Wednesday 23 April to Wednesday 14 May 2025.