What’s clear from the devastating flood events to hit parts of Queensland since the summer of 2010–11 is the need for a considered approach to building and development works to make Queensland cities and towns more resilient to the effects of flooding.
Given that floods are familiar events in Queensland, and the costs of damage, clean-up and rebuilding are significant, why are flood-affected homes usually replaced with like-for-like designs post-flood? Why do new developments generally adopt standard design where it is not possible to build above a certain height? And, the biggest question of all, why are flood resilient designs not used more widely?
Drilling down on these questions was the goal of a one-and-a-half-day research synthesis workshop in March 2018, facilitated by the CRCWSC and James Davidson Architect, as part of the wider Brisbane River Catchment Strategic Floodplain Management Plan development process. The workshop sought to identify and resolve barriers to the adoption of flood resilient design principles at the local level in Queensland—and the resulting ideas are now outlined in the newly released report, Ideas for catalysing flood resilient design.
What is flood resilient design?
Flood resilient design is the use of materials, construction systems and design typologies that can withstand substantial and multiple inundations in actively mitigating the effects of, and minimising the cost of, flooding to enable home owners to safely store belongings prior to an inundation event, and easily clean, repair and quickly move back in after such an event, with minimal long term disruption to family and finances.
So, flood resilient design offers an affordable and resilient design solution, based on keeping water out of buildings and allowing water to enter a building in a controlled way, to enable a faster clean out and return to normal living. It can apply to buildings already subject to flood impacts, and to new construction that is already above a defined flood datum.
Four ideas for flood resilient design resulted from the workshop
Workshop participants identified the barriers and opportunities to flood resilient design and then converted them into four ideas that could embed flood resilient approaches as part of ‘business as usual’ in flood-prone areas. Broadly, participants saw the need to increase industry capacity and capability as well as engage industry in the development of a suite of flood resilient design tools. Specifically, they identified these four main ideas, plus many smaller concepts within them:
- Catchment planning integration
- Living with water
- Broad participation
- ‘Roll back’ the flood
Catchment planning integration—This idea is about an understanding of the system that governs development in Queensland and the need for a more integrated approach to catchment management. It takes a catchment-scale perspective to planning and seeks to (1) integrate land use and water management outcomes and (2) align planning requirements across jurisdictional boundaries to deliver these .
Other concepts within this idea are:
- Integrated catchment planning
- Harmonising planning controls and building controls
- Understanding the ‘actors’ in the system and their perspectives.
Living with water—This idea shows how to better manage the impacts of water in flood-prone areas, accepting that it is not possible to exclude flood waters in these locations. This idea includes:
- Offering property owners and the building industry new incentives for adopting flood resilient design because they are largely unaware of the benefits or are prejudiced against it on the grounds of cost
- Developing a new web-based tool or calculator to estimate the benefits of flood resilient design and mitigate the perception of additional cost as a barrier
- Creating a flood resilience rating tool to guide the building industry, help the insurance sector assess risk, and allow governance to prioritise investment
- Introducing a mandatory provision in the planning scheme to embrace flood resilient design below and above the defined flood level
- Developing a rating system for flood resilient materials and products to indicate their fitness for purpose
- Developing a web-based tool to provide independent advice on how to incorporate flood resilient design into properties.
Broad participation—This idea connects the different parts of industry that play a role in flood resilience, and includes:
- Offering incentives, via the insurance, government and banking and finance sectors, for property owners to make their properties more flood resilient during a rebuild
- Taking a risk-based approach to characterising the variation in risk across the floodplain, identifying areas of greatest concern in terms of both current and future conditions, and using ‘potential hydraulic risk’ as the foundation for informing risk-based land use planning
- Making flood risk searches and due diligence checks mandatory during conveyancing
- Supporting industry participation in making flood resilient design ‘business as usual’, including a skills gap survey and training program.
‘Roll back’ the flood—This idea focuses on proactively managing the catchments, and implementing catchment-wide changes over a long time period, to reduce runoff rates and flood risk. This idea recognises that the climate is changing, and it is likely that existing flood risk may alter in the future due to increased rainfall intensity and sea level rise. This idea encompasses using landscape management and water sensitive urban design, and developing a ‘waterprint’ or framework to maintain greater space for green and blue infrastructure, while maintaining development yields to accommodate population growth.
These ideas sit within a broader process
The flood resilient workshop in Queensland is an example of the CRCWSC’s research synthesis process in action. You can learn more about this dynamic process in this video.
For this project, the CRCWSC’s research synthesis workshop ran in parallel with other activities by James Davidson Architect to develop the Flood resilience building guidance for Queensland homes (2018) Brisbane River Catchment Flood Studies. The workshop outputs were used to inform this guidance and to offer pathways to implement flood resilient building design in Queensland.
The four ideas from the workshop respond to the need for, and can catalyse the uptake of, flood resilience design for urban development. Guidance for the designs themselves are described in a separate report, Flood resilient building guidance for Queensland homes (Queensland Reconstruction Authority 2019).