Bushfire Risk Assessment at the Urban-Bush Interface (Ubi) in Sydney, Australia: an Integrated Modelling Approach
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BUSHFIRE RISK ASSESSMENT AT THE URBAN-BUSH INTERFACE (UBI) IN SYDNEY, AUSTRALIA: AN INTEGRATED MODELLING APPROACH Daminda Thushara Solangaarachchi BSc (Hons), MSc (GIS & RS) A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy School of Physical, Environmental & Mathematical Sciences The University of New South Wales Australian Defence Force Academy Canberra, ACT, 2600, Australia 31 August 2012 ii ORIGINALITY STATEMENT ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ Signed …………………………………………….......... Daminda Thushara Solangaarachchi 31 August 2012 iii iv ABSTRACT Bushfire Risk Assessment at the Urban-Bush Interface (UBI) in Sydney, Australia: An Integrated Modelling Approach Bushfires are one of the major threats to the environment and human systems in Australia. The recent 2009 Black Saturday bushfires in Victoria claimed more than 2,029 homes and 173 lives, and demonstrated that fire management authorities need to rethink their current risk and emergency management approaches. Rapid population growth and land use change at the urban-bush interface combined with favourable weather conditions for bushfires are causing a rapid increase in vulnerability of communities exposed to bushfires. Identifying vulnerability and risk before an event occurs are essential steps towards efficient and effective risk management. Global initiatives such as the United Nations International Decade for Natural Disaster Reduction (IDNDR) and Hyogo Framework for Action (HFA) have highlighted the importance of research for formulating the overall value of disaster risk reduction through national and local risk assessments. In order to achieve that, it is necessary to ‘measure’ the existing level of risk and the potential future risk that may be encountered in future bushfire events. In Australia, various institutions and agencies have developed a variety of bushfire risk assessment models. However, many of these models focus primarily on the hazard component of risk, which is mainly based on physical factors such as weather, fuel, and topography. A risk assessment model that integrates both the hazard component and the elements of vulnerability such as social vulnerability, physical vulnerability, and emergency response and coping capacity is yet to be developed. Risk assessments often use objective, quantifiable approaches. However, assessing the objective level of risk itself is not enough for efficient risk management decision-making. Understanding subjective judgements of residents living at urban-bush interface, the factors affecting their decisions and their perceptions of bushfire risk and attitudes towards current bushfire management strategies is also an important step towards effective bushfire risk management. Despite the considerable effort that has been directed towards encouraging bushfire preparedness in Australia, research on public perceptions of bushfire management strategies to reduce bushfire risk is relatively rare. v This thesis develops a multifaceted understanding of vulnerability and risk based on a holistic approach to risk. In this research, the hazard component is recognised as the product of the probability of occurrence and the severity of an event. Vulnerability is shown to arise from the inherent socioeconomic conditions of households, the exposure and physical succesptibility of locations and a community’s capactity to respond and cope with hazard events. Risk is identified as a function of hazard and vulnerability. To understand these different dimensions, a mixed methods approach was utilised in this thesis. A quantitative method was developed for a multidisciplinary evaluation of risk that assesses its different components individually and then combines them algorithmically. A GIS-based, Fuzzy Multi Criteria Evaluation (FMCE) method was utilized to integrate the components of risk. Such techniques also enable appropriate means of quantification and visualization of complex data in map form. Qualitative methods were primarily used to investigate subjective questions such as perceptions, household and community level preparedness activities. Household surveys and semi- structured interviews with local residents, community fire volunteers, local council members and others who participated in responses to the fires were conducted to capture such information. Exploratory data analysis was performed to understand these subjective judgements and the results were presented in graphical format. This thesis demonstrates the fundamental importance of understanding the multi- dimensional characteristics of risk in managing bushfire risk at the urban bush interface. The results revealed the spatial variation of composite risk as well as the elements of risk; hazard and vulnerability. It identified important physical and socioeconomic dimensions of vulnerability and the response and coping capacities of the communities. These variations help to prioritise different disk reduction initiatives in different areas. It also found different perceptions and attitudes of residents towards bushfire management activities. This information could help to further modify the risk reduction measures in order to address specific household and community level issues. The overall results of this thesis will provide a framework to strengthen the risk reduction measures that engage in anticipating future disaster risk, reducing existing exposure, hazard, or vulnerability, and improving community capacities to cope with hazard events. vi PUBLICATIONS RELATED TO THIS THESIS Journal Article Solangaarachchi D., Griffin A.L., Doherty M.D., Social Vulnerability in the Context of Bushfire Risk at the Urban Bush Interface in Sydney: A Case Study of the Blue Mountains and Ku-ring-gai Local Council Areas, Natural Hazards: Journal of the International Society for the Prevention and Mitigation of Natural Hazards, DOI: 10.1007/s11069-012-0334-y vii viii ACKNOWLEDGEMENTS First and foremost I want to thank my supervisor, Dr. Amy L. Griffin for her valuable guidance and encouragement throughout the research process. She provided constructive comments and helped me to navigate obstacles and recognise the opportunities during the process. She has always being patient and willing to listen. I am fortunate to have had the opportunity to study under her guidance. I also wish to express profound respect to my co-supervisor Michael D. Doherty for his constructive suggestions and guidance in improving this research. This work would not have been possible without the interest of the members of the public in Ku-ring-gai and the Blue Mountains who received and responded to my survey. Most people were happy to participate in the survey, and even some people who didn’t participate found it useful. I would like to thank them for assisting me in gaining an in-depth knowledge of my study area. The support I got from the local councils and NSW Fire and Rescue (NSWFR) was very helpful. I would like to express my thanks to Greg Buckley (NSWFR), Dr. Jenny Scott and Jennie Cramp (Ku-ring-gai Council), and Peter Belshaw (Blue Mountains City Council) for helping me to complete this research. The key data and information used for this study was provided by Local councils, Land and Property Management Authority, NSW Rural Fire Services and NSW Fire and Rescue. Without these data, this study would not have been possible. Their provision of data is greatly appreciated. This research was financially supported by School of Physical, Environmental and Mathematical Sciences at the UNSW Canberra and, I extend my thanks and appreciation to the school for its support. My appreciation also extends to the PEMS administration team for the many ways they helped throughout my research. I am indebted to Ms Julie Kesby for her excellent help with regards to referencing, thesis formatting, and gathering resources for my study. Special thanks to my dear colleagues in the Geographers’ room, especially Solomon, Dustin and Vijai. So many good ideas were born with what started as random ix conversations in the room. I will always remember the time we spent discussing, arguing, and laughing. I am deeply grateful to my parents for teaching me the value of education, and who sacrificed the best times of their lives for my education. I would not have come this far without their support. My brothers, thank you for being my best friends during my journey. Your love and support has given me the strength I needed to walk along this path. My heartfelt thanks also go to my father-in-law who have always supported me and encouraged me to pursue my goals wherever they took me. A final word of thank to my wife, Beyandi, for love, encouragement, support and good food. Thank you for being understanding during those late nights and early mornings. Without your continuous support, love