Resilience to inland flooding: Queensland flood risk management framework
Increasing Queensland’s resilience to inland flooding in a changing climate: Queensland’s Inland Flood Study
Floods are one of the most prominent natural hazards facing Queensland. The January 2011 floods in Toowoomba, Lockyer Valley and Brisbane, which resulted in loss of life and billions in economic damage, are a testament to the dynamic relationship between the natural and built environment.
There is a strong relationship between increasing temperatures, the result of climate change, and increased water vapour ino the atmosphere. In turn an increase in water vapour can lead to a likely increase in heavy rainfall events and subsequent flooding (Allen & Ingram 2002). The Queensland Government has used these relationships to look at future flooding under climate change.
The report of this initiative, with the main findings of the study can be accessed at http://www.climatechange.qld.gov.au/pdf/inlandfloodstudy.pdf
This case study examines Queensland’s response to managing the relationship between anticipated increases in precipitation and planning for human settlements.
Triggers for Action
Councils are at the forefront of land use planning and are often challenged with the task of incorporating natural hazard planning into their strategic planning mechanisms. The confluence between an expanding population, recent flooding and a growing awareness of climate change has led to an emerging concern about how councils can best consider climate change in future inland flood planning.
The triggers for action came from advice given to Gayndah Shire Council from hydrologists about the suggested level of climate change perturbations in their flood modelling. The council then approached the Local Government Association of Queensland (LGAQ) seeking advice and clearer guidelines. Subsequently “the Queensland Government, in collaboration with LGAQ, undertook this project to deliver a more definitive approach to managing inland flooding risks in a changing climate, based on the best available science and implemented via the Queensland land use planning framework.” (Queensland Government 2010a, p.4)
A Collaborative Response for Adaptive Action
The focus of the Project was to use sound science and best planning options to provide guidance for councils when applying climate change perturbations in flood modelling. The project was undertaken by the Office of Climate Change (Queensland Department of Environment and Resource Management), the Queensland Department of Infrastructure and Planning and the Local Government Association of Queensland. An advisory board was established to oversee the project. This was chaired by the Queensland Office of Climate Change and included participants from:
- Local Government Association of Queensland (LGAQ).
- CSIRO Climate Adaptation Flagship
- The National Climate Change Adaptation Research Facility (NCCARF)
- Griffith University
- Department of Infrastructure and Planning
- Department of Community Safety
- Department of Environment and Resource Management.
The Inland Flood Study Project utilised the best scientific evidence available together with input from a broad range of stakeholders to identify a uniform approach to flood management. Recommendations from the Inland Flood Study Project include:
Recommendation 1 — For every 10C of expected temperature increase due to climate change, local governments should factor in a 5% increase in rainfall intensity into the 1 per cent (Q100), 0.5 per cent (Q200) and 0.2 per cent (Q500) AEP flood events recommended in the State Planning Policy documentation for the location and design of new development (see Box 1).
Recommendation 2 —The following temperatures and timeframes should be used for the purposes of applying the climate change factor in Recommendation 1: 2.0ºC [of warming] by 2050; 3.0ºC by 2070; and 4.0ºC by 2100 [these are based on the findings in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (IPCC 2007) shown in Table 1]. Thus, the estimates of flood height should be increased by 10% for 2050 and by 20% for 2100 relative to present day flood heights.
Recommendation 3—The Queensland Government will review and update this climate change factor when a national position on how to factor climate change into flood studies is finalised as part of the current review of the Australian Rainfall and Runoff Project (AR&R).
The Inland Flood Project recommended that the councils follow the process outlined below (Figure 1) when considering climate change in flood modelling.
Figure 1. Flow chart of climate change flooding risk assessment based on temperature changes (Queensland Scientific Advisory Group, 2010).
- A Scientific Advisory Group (SAG) was established to review the current robust science linking temperature with rainfall intensity.
- General Circulation Models are used to project future climate. Results from these were examined with respect to what they could tell about future rainfall trends. However, different models give different projections for rainfall, even with respect to sign, meaning that their results could not form a robust foundation for the work.
- On the basis of the literature review, the SAG concluded that due to issues surrounding uncertainty of climate models for rainfall the “Clausius-Clapeyron theory provides the most robust interim measure on which to base the increases in rainfall intensity” (Queensland Government 2010b, p.8). The Clausius-Clapeyron theory assigns a correlation between average atmospheric warming and increased rainfall intensity suggesting that “for each 1ºC increase in temperature, the amount of water vapour a parcel of air can hold increases by approximately 7%” (Queensland Government 2010b, p.3);
- The SAG reviewed other national and international flood planning responses for climate change including examples from NSW, Victoria, Western Australia, New Zealand and the United Kingdom.
Information was distributed via a range of media including a press release, online publishing and distribution by LGAQ and relevant stakeholders.
IPCC (2007) Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, available from http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf
Queensland Government (2010a) ‘Increasing Queensland’s resilience to inland flooding in a changing climate: Final report on the Inland Flooding Study report prepared by Department of Environment and Resource Management, Department of Infrastructure and Planning, Local Government Association of Queensland, available from http://www.climatechange.qld.gov.au/pdf/inlandfloodstudy.pdf
Queensland Government (2010b) ‘Increasing Queensland’s resilience to inland flooding in a changing climate, Final Scientific Advisory Group (SAG) report—Derivation of a rainfall intensity figure to inform an effective interim policy approach to managing inland flooding risks in a changing climate’, report prepared by Department of Environment and Resource Management, Department of Infrastructure and Planning, Local Government Association of Queensland, available from http://www.climatechange.qld.gov.au/pdf/sag-report.pdf
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