Natural hazards and resilience in complex urban systems

Australia is one of the world’s most urbanised countries with a little over 86% of its total population living in a major urban centre. Just under 60% of the population live in the four largest cities: Sydney, Melbourne, Brisbane and Perth. It is expected that 75% of Australia’s projected future population growth will occur in these four cities (Infrastructure Australia, 2018).

Australia’s urban areas are variously exposed to multiple and interacting natural hazards, such as extreme heat, severe rain and hail events, storm surges and coastal inundation, floods, tropical cyclones, bushfires on their outskirts and earthquakes. Such natural hazards can lead to disasters when they trigger multidimensional, cascading and compounding impacts that exceed the coping capacities of urban systems. The frequency and intensity of some of these natural hazards are projected to increase due to climate change while rapid urbanisation, and demographic, social and economic shifts change urban landscapes and systems. In the face of this future hazard intensification, “a more mature understanding of the root causes and effects of disaster risk and systemic vulnerability is needed, so that our efforts to mitigate the risk and build resilience can meet the challenges of the future” (Department of Home Affairs, 2018a, p.4).

This report summarises the findings of the Natural Hazards Research Australia-funded project Natural hazards and resilience in complex urban systems. The project is grounded conceptually in the concept of ‘the city as a system of systems’ and the complex interactions and relationships between urban systems. This complex, tightly interconnected and dynamic nature of urban systems complicates risk assessment and disaster risk reduction in urban settings, as decisions, coordination and action by multiple levels of government, businesses, community organisations and households impact on risk and risk management. Moreover, urban areas are highly diverse – not only spatially, physically and economically, but also socially, culturally and politically. The impacts of a natural hazard event on an urban system, including its people and the built environment, therefore depends on “where, when and to whom it occurs” (Gabriel et al., 2019, p.1) – and in terms of building resilience to hazard and disaster risk in cities, the issue of “whose resilience and whose city” becomes important (Vale, 2013, p.191).

A systems perspective can identify significant issues and the root causes of urban hazards and disaster risk, and enable us to identify ways of reducing or mitigating those risks. Meadows (2008) defines a system as “an interconnected set of elements that is coherently organised in a way that achieves something”. In context of urban environments, systems thinking provides concepts and tools that go beyond studying the individual elements of a system to comprehend the full extent of its complexity – and to appreciate that the seemingly intractable problems and crises brought on by exposure and vulnerabilities to hazard events are created by the very systems in which they arose (Cabrera & Cabrera, 2023; Forrester, 2022; Meadows, 2008). An important first step in building urban resilience is increasing our understanding of the systemic nature of risks and vulnerabilities. At the same time, it is necessary to understand the context of current thinking, actions and decision-making to improve our actions, processes and procedures towards risk reduction and building resilience.

The findings of the project are intended to help us better understand how to prepare urban environments and those who live in them to be resilient to natural hazards and their cascading impacts. The study had three aims:

1. To increase understanding within the emergency management sector of:

• the systemic nature of urban centres and the multidimensional, compounding and cascading impacts arising from natural hazard events for communities located in major urban areas in Australia
• the ways in which these impacts may change over time under the influence of climate change, rapid urbanisation, and other factors to influence urban resilience
• the nature, scope and purpose of urban resilience policies and strategies.

2. To develop guidance for local and state governments, emergency services and community organisations to conceptually map vulnerabilities and resilience within urban systems at local scales; and demonstrate its application with a proof-of-concept case study.

3. To develop process principles and standards for use by local and state governments, emergency services and community organisations to effectively prioritise and influence urban resilience investment at local, state and federal levels; and monitor and evaluate the outcomes of investment decisions.

To address these three objectives, three project phases (or Work Packages) were undertaken, complemented by a fourth phase involving dissemination, communication and capacity building activities to support the translation and adoption of research findings of the project.

• Phase 1 has analysed the state of knowledge of multidimensional, compounding and cascading disaster impacts in major urban areas, how these impacts may change over time, and the ways urban disaster risk is a product of the complex interdependencies among urban systems and subsystems, thereby emphasising the need for resilience building.
• Phase 2 has explored current and emerging practices for conceptualising and mapping vulnerabilities and resilience and reflected upon practices and how resilience thinking and practice may be advanced employing a systemic view of cities.
• Phase 3 has investigated current practices of prioritising and influencing urban resilience investments and considered principles and processes for decision-making for investing in different strategies for building urban resilience.
• Phase 4 has translated the research of Phases 1 to 3 into a Practical guidance tool for conceptual mapping of resilience and vulnerability in complex urban systems (including a proof-of-concept study), Principles and Recommendations for Urban Resilience Investment and guidance on monitoring and evaluating resilience investments. The Phase furthermore involved presentations, webinars and developing communication products.