Floodplain Management Australia (FMA) Webinar Series

28 January – 11 February Episode: Toowoomba’s Evolution in Flood Modelling and Floodplain Management

Background

Floodplain Management Australia (FMA) is the peak national body for flood risk practitioners in Australia. TUFLOW have been a long time supporter of FMA, and year on year assist the organisation via conference sponsorship. 

FMA are running a Member exclusive webinar series. The series features some of the most popular presentations from the FMA Conference program. A new webinar is published fortnightly, and remains available for viewing over a two week period via the Members’ Section of https://www.floods.org.au/. This week’s episode is an interesting presentation by Zita Dore discussing an impressive project using TUFLOW, where BMT did flood modelling at an scale covering the entire Toowoomba Regional Council local government area (details below).

If you're a member and have not registered for access to the Members Section, contact projectservices@floods.org.au. If you aren’t an FMA Member, but are interested in joining a network of over 160 councils, catchment management authorities, organisations and flood risk professionals, visit floods.org.au/membership.

Webinar: Toowoomba’s Evolution in Flood Modelling and Floodplain Management

Speaker: Zita Dore, BMT

Webinar Expiry: 11 February, 2021:

Abstract: The Toowoomba region experienced a catastrophic flood event in 2011, prompting Toowoomba Regional Council (TRC) to commence an ambitious project to prepare flood mapping for more than 30 towns, which influenced the Flood Risk Assessment, Planning Evaluation and Planning Scheme Amendment (FRAPESA) Project. This project won the Flood Risk Management Project of the Year at Floodplain Management Australia’s 2018 conference.

Following the completion of this project, Council identified that an understanding of flood behaviour for the remainder of the TRC area (i.e. rural areas between towns) should be mapped. The TRC - wide Regional Flood Study project was commenced in 2017 and aimed to develop rapid, low-cost flood extent mapping for the 1% AEP design flood event covering the TRC area in its entirety. In 2019, these regional models were updated to provide more comprehensive and accurate flood mapping, understanding of hazard, immunity and flood behaviour.

The model update involved including major structures and calibration to two historic events. Australian Rainfall and Runoff 2019 (ARR2019) was adopted for design event modelling and a full range of flood events from the 50% AEP event to the Probable Maximum Flood (PMF) were simulated.

The models provide a number of advantages and information sources for Council to better inform FRAPESA but also other Council activities such as planning for future roadworks, bridges and major culvert upgrading projects. These rural areas previously relied on historic flood information or topographic-based assessments and would require site-specific flood models for major infrastructure or developments. Now, Council, developers and the broader community have an improved understanding of flood risk across the region.

There were a number of challenges to achieving such an ambitious scope of works but the innovative solutions developed clearly demonstrated the potential for LGA-wide mapping, which provides comprehensive mapping beyond major town centres.