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University of New South Wales (UNSW) 2013

Bushfire Risk Assessment at the Urban-Bush Interface (UBI) in Sydney, Australia : An Integrated Modelling Approach

Solangaarachchi, Daminda

Titre : Bushfire Risk Assessment at the Urban-Bush Interface (UBI) in Sydney, Australia : An Integrated Modelling Approach

Auteur : Solangaarachchi, Daminda

Université de soutenance : University of New South Wales (UNSW)

Grade : Doctor of Philosophy (PhD) 2013

Résumé
Bushfires are one of the major threats to the environment and human systems inAustralia. The recent 2009 Black Saturday bushfires in Victoria claimed more than2,029 homes and 173 lives, and demonstrated that fire management authorities need torethink their current risk and emergency management approaches. Rapid populationgrowth and land use change at the urban-bush interface combined with favourableweather conditions for bushfires are causing a rapid increase in vulnerability ofcommunities exposed to bushfires. Identifying vulnerability and risk before an eventoccurs are essential steps towards efficient and effective risk management. Globalinitiatives such as the United Nations International Decade for Natural DisasterReduction (IDNDR) and Hyogo Framework for Action (HFA) have highlighted theimportance of research for formulating the overall value of disaster risk reductionthrough national and local risk assessments. In order to achieve that, it is necessary to‘measureÂ’ the existing level of risk and the potential future risk that may be encounteredin future bushfire events.In Australia, various institutions and agencies have developed a variety of bushfire riskassessment models. However, many of these models focus primarily on the hazardcomponent of risk, which is mainly based on physical factors such as weather, fuel, andtopography. A risk assessment model that integrates both the hazard component and theelements of vulnerability such as social vulnerability, physical vulnerability, andemergency 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. Understandingsubjective judgements of residents living at urban-bush interface, the factors affectingtheir decisions and their perceptions of bushfire risk and attitudes towards currentbushfire management strategies is also an important step towards effective bushfire riskmanagement. Despite the considerable effort that has been directed towardsencouraging bushfire preparedness in Australia, research on public perceptions ofbushfire management strategies to reduce bushfire risk is relatively rare.This thesis develops a multifaceted understanding of vulnerability and risk based on aholistic approach to risk. In this research, the hazard component is recognised as theproduct of the probability of occurrence and the severity of an event. Vulnerability isshown to arise from the inherent socioeconomic conditions of households, the exposureand physical susceptibility of locations and a communityÂ’s capacity to respond andcope with hazard events. Risk is identified as a function of hazard and vulnerability. Tounderstand these different dimensions, a mixed methods approach was utilised in thisthesis. A quantitative method was developed for a multidisciplinary evaluation of riskthat assesses its different components individually and then combines themalgorithmically. A GIS-based, Fuzzy Multi Criteria Evaluation (FMCE) method wasutilized to integrate the components of risk. Such techniques also enable appropriatemeans of quantification and visualization of complex data in map form. Qualitativemethods were primarily used to investigate subjective questions such as perceptions,household and community level preparedness activities. Household surveys and semistructured interviews with local residents, community fire volunteers, local councilmembers and others who participated in responses to the fires were conducted tocapture such information. Exploratory data analysis was performed to understand thesesubjective judgements and the results were presented in graphical format.This thesis demonstrates the fundamental importance of understanding the multidimensional 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. Italso found different perceptions and attitudes of residents towards bushfire managementactivities. This information could help to further modify the risk reduction measures inorder to address specific household and community level issues. The overall results ofthis thesis will provide a framework to strengthen the risk reduction measures thatengage in anticipating future disaster risk, reducing existing exposure, hazard, orvulnerability, and improving community capacities to cope with hazard events.

Mots clés : Hazard ; Bushfire risk ; Urban bush interface ; Vulnerability ; Emergency response capacity ; GIS ; Spatial Modelling ; Fuzzy Multi Criteria Evaluation

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Page publiée le 29 novembre 2014, mise à jour le 6 juillet 2017