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

Abstract

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. 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 susceptibility of locations and a community s capacity 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 semistructured 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 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. 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.