Flood Studies

Since 2018, Townsville City Council has been carrying out flood studies to create new flood models. Flood studies help us understand how rainfall events are likely to affect flooding across the landscape.

Townsville Recalibrated Flood Modelling and Mapping Project (TRFMMP)

The many rivers and creeks across Townsville form distinct catchment systems where rainfall can flow towards the ocean. The Townsville Recalibrated Flood Modelling and Mapping Project (TRFMMP) has now undertaken flood studies for nine of these major catchments.

The studies have produced flood models, help us to understand how flooding is likely to affect these catchments under a variety of different rainfall scenarios. These models have been peer reviewed by an independent third party to ensure their accuracy. Some further models are now being completed for the Bohle River catchment, which will help give us further understanding of how flooding affects that area. Council will release these models and update risk mapping for the Bohle once complete. Please note, this will not change the new 1% AEP Depth Mapping.

What are the catchments?

The TRFMMP study catchments are listed below. Expand the catchment name to access the technical flood study reports.

IMPORTANT NOTE - Some of the below reports are very large files. Please read the file size details before downloading.

ABOVE: TRFMMP floodplain catchment areas.

In addition, other Council projects have produced further flood studies which have been used to plan for flood resilience in Townsville.

Lansdown Station Flood Study - Baseline Flooding Assessment

The Lansdown Station flood study was completed in 2018 and assisted the formation of the Lansdown Eco-Industrial Precinct at Calcium, which rezoned to High Impact Industry in 2020. This study has already been published and the model was used to create the current flood hazard mapping for Lansdown Eco-Industrial Precinct. As with the other flood models, we are now using the data to create risk mapping.

Download the Lansdown Station Baseline Flooding Assessment (45MB - PDF).

Sleeper Log Creek Model

In 2023, a separate Council study on environmental flow paths required a flood model to be produced for the Sleeper Log Creek catchment. This model is also being used to create new flood mapping and planning for flood resilience.

• Download the Sleeper Log Creek Flood Impact, Resilience and Risk Study Vol 1 (18MB - PDF)
• Download the Sleeper Log Creek Flood Impact, Resilience and Risk Study Vol 2 (41MB - PDF)

What are flood models?

Flood models contain likely flooding extent, depths, and velocities for different flooding scenarios. The TRFMMP models include present-day scenarios and climate change scenarios that account for climate change impacts to the year 2100. These scenarios include:

• 50% AEP
• 20% AEP
• 10% AEP
• 5% AEP
• 2% AEP
• 1% AEP
• 0.2% AEP
• 0.05% AEP
• PMF – Probable Maximum Flood
• 2% AEP with climate change
• 1% AEP with climate change

AEP – Annual Exceedance Probability is the probability that a flood of that magnitude or larger will occur in a given year. For example, a 1% AEP has a one percent chance of a flood this size or larger occurring any given year.

How are flood models calculated?

Flood models are created using a variety of data inputs including:

• Hydraulic and hydrologic modelling tools
• Updated rainfall data
• Stream gauge data
• Topography data (LiDAR)
• Satellite imagery
• Land use data
• Survey data
  - Bathymetric
  - Drainage channels
• Stormwater drainage structures
• Flood level data
• Plans for recent developments

The flood models are based on on-ground data for a particular moment in time. The new development and natural processes change the landscape, this can change the nature of flooding. When planning for flood, larger new developments will have to consider these changes. Council will periodically update its flood studies to reflect these changes.

Previous Flood Studies

Council’s new flood studies have the best and most accurate information about how flooding is likely to affect Townsville; however, Council’s previous flood studies are still available to be viewed. While Council wants the community and industry to use the new flood studies, these previous flood studies still inform the current hazard overlay mapping in the Townsville City Plan. Until the overlay maps are updated it is necessary to ensure these older models are available.

Council is taking steps to update the flood maps for ensuring better building and planning decisions in our city.

What about areas outside the flood studies?

The flood study areas cover mostly the urban areas of Townsville; however, there are some locations outside of these flood study areas that may still be susceptible to flood. While we have less detailed flood information about these areas, the Queensland Reconstruction Authority has mapped them, and they are also shown in Council’s Flood Information Portal mapping.

How are the flood models being used?

Our flood models are used to create the flood depth maps and flood risk maps for Townsville. They are a powerful tool for our City Planners, enabling us to make better planning decisions to improve the resilience of our community.

Flood Maps

Using the data from the flood models, Council has created maps to show how flooding affects the Townsville area. You can find these maps on the Flood Information Portal.

Risk Assessment

A floodplain risk assessment combines models, with other information such as building flood levels, planning zones and land uses, warning times, roads and evacuation routes, vulnerable uses, and critical infrastructure. Using this information, the risk assessment calculates the levels of risk in different locations.

Better Planning

With new flood models we can make better planning decisions to improve the resilience of our community. Council and developers can access the flood models to ensure large new developments achieve an appropriate level of flood immunity and do not make flooding worse to surrounding areas. Additionally, with new flood maps, new buildings can be built with appropriate floor levels.

Based on the modelling and the floodplain risk assessment, Council has proposed planning policies to respond to flood risk in the Townsville City Plan. Council is seeking community feedback on these responses via our Have Your Say website.

Requesting flood models

Flood models can be requested by developers to help inform development scenarios and understand the impact on flooding. Requests can be made by completing the Flood Model Request Form below.