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Article

Human Extinction from Natural Hazard Events  

Anders Sandberg

Like any other species, Homo sapiens can potentially go extinct. This risk is an existential risk: a threat to the entire future of the species (and possible descendants). While anthropogenic risks may contribute the most to total extinction risk natural hazard events can plausibly cause extinction. Historically, end-of-the-world scenarios have been popular topics in most cultures. In the early modern period scientific discoveries of changes in the sky, meteors, past catastrophes, evolution and thermodynamics led to the understanding that Homo sapiens was a species among others and vulnerable to extinction. In the 20th century, anthropogenic risks from nuclear war and environmental degradation made extinction risks more salient and an issue of possible policy. Near the end of the century an interdisciplinary field of existential risk studies emerged. Human extinction requires a global hazard that either destroys the ecological niche of the species or harms enough individuals to reduce the population below a minimum viable size. Long-run fertility trends are highly uncertain and could potentially lead to overpopulation or demographic collapse, both contributors to extinction risk. Astronomical extinction risks include damage to the biosphere due to radiation from supernovas or gamma ray bursts, major asteroid or comet impacts, or hypothesized physical phenomena such as stable strange matter or vacuum decay. The most likely extinction pathway would be a disturbance reducing agricultural productivity due to ozone loss, low temperatures, or lack of sunlight over a long period. The return time of extinction-level impacts is reasonably well characterized and on the order of millions of years. Geophysical risks include supervolcanism and climate change that affects global food security. Multiyear periods of low or high temperature can impair agriculture enough to stress or threaten the species. Sufficiently radical environmental changes that lead to direct extinction are unlikely. Pandemics can cause species extinction, although historical human pandemics have merely killed a fraction of the species. Extinction risks are amplified by systemic effects, where multiple risk factors and events conspire to increase vulnerability and eventual damage. Human activity plays an important role in aggravating and mitigating these effects. Estimates from natural extinction rates in other species suggest an overall risk to the species from natural events smaller than 0.15% per century, likely orders of magnitude smaller. However, due to the current situation with an unusually numerous and widely dispersed population the actual probability is hard to estimate. The natural extinction risk is also likely dwarfed by the extinction risk from human activities. Many extinction hazards are at present impossible to prevent or even predict, requiring resilience strategies. Many risks have common pathways that are promising targets for mitigation. Endurance mechanisms against extinction may require creating refuges that can survive the disaster and rebuild. Because of the global public goods and transgenerational nature of extinction risks plus cognitive biases there is a large undersupply of mitigation effort despite strong arguments that it is morally imperative.

Article

Volcanoes and the Human and Physical Geographies of Risk  

Amy Donovan

Volcanic risk is highly complex, and incorporates social, economic, physical, infrastructural, and cultural elements. It is also high stakes, but low probability—making it particularly challenging for governments to manage. Substantial advances in the understanding of volcanic processes, hazards, and monitoring signals can enable scientists to forecast volcanic activity in many cases, but high levels of uncertainty remain. Volcanology itself is a relatively young science, emerging in the 20th century following the growth of the geological sciences in the post-Enlightenment period. Crises in the late 20th and early 21st century have demonstrated the complexity of applying uncertain scientific models in particular, local, and politically challenging contexts. Volcanology continues to make advances in integrating disciplines—particularly in the combination of physical hazard science with impact assessment, and increasingly with the social sciences. Volcanic eruptions can also substantially alter the power dynamics in a particular context, as volcanologists’ forecasts can become all-consuming for local populations. This is challenging both for scientists and for political officials and populations coming to terms with the threat they may face. The critical geography of disasters, as it incorporates these issues of relationality, must also learn from the action research literature and develop and deploy interventions that can change the emerging possibility spaces within an emergent disaster assemblage. Understanding the relational processes of sociomaterial disasters through an “imaginations” lens can enable interventions to be identified at an early stage.

Article

The Governance of Flood Risk Management  

Jason Thistlethwaite and Daniel Henstra

Natural hazards are a complex governance problem. Managing the risks associated with natural hazards requires action at all scales—from household to national—but coordinating these nested responses to achieve a vertically cohesive course of action is challenging. Moreover, though governments have the legal authority and legitimacy to mandate or facilitate natural hazard risk reduction, non-governmental actors such as business firms, industry associations, research organizations and non-profit organizations hold much of the pertinent knowledge and resources. This interdependence demands horizontal collaboration, but coordinating risk reduction across organizational divides is fraught with challenges and requires skillful leadership. Flood risk management (FRM)—an integrated strategy to reduce the likelihood and impacts of flooding—demonstrates the governance challenge presented by natural hazards. By engaging stakeholders, coordinating public and private efforts, and employing a diversity of policy instruments, FRM can strengthen societal resilience, achieve greater efficiency, and enhance the legitimacy of decisions and actions to reduce flood risk. Implementing FRM, however, requires supportive flood risk governance arrangements that facilitate vertical and horizontal policy coordination by establishing strategic goals, negotiating roles and responsibilities, aligning policy instruments, and allocating resources.

Article

A Relational Approach to Risk Communication  

Jing Zhu and Raul P. Lejano

It is instructive to juxtapose two contrasting models of risk communication. The first views risk communication as a product that is packaged and transmitted, unmodified and intact, to a passive public. The second, a relational approach, views it as a process in which experts, the public, and agencies engage in open communication, regarding the public as an equal partner in risk communication. The second model has the benefit of taking advantage of the public’s local knowledge and ability to engage in risk communication themselves. Risk communication should be understood as more of a dynamic process, and less of a packaged object. An example of the relational model is found in Bangladesh’s Cyclone Preparedness Programme, which has incorporated the relational model in its disaster risk reduction training for community volunteers. Nevertheless, the two contrasting models, in practice, are never mutually exclusive, and both are needed for effective disaster risk prevention.

Article

Collective Choices Affecting Natural Hazards Governance, Risk, and Vulnerability  

Thomas Thaler, David Shively, Jacob Petersen-Perlman, Lenka Slavikova, and Thomas Hartmann

The frequency and severity of extreme weather events are expected to increase due to climate change. These developments and challenges have focused the attention of policymakers on the question of how to manage natural hazards. The main political discourse revolves around the questions of how we can make our society more resilient for possible future events. A central challenge reflects collective choices, which affect natural hazards governance, risk, and individual and societal vulnerability. In particular, transboundary river basins present difficult and challenging decisions at local, regional, national, and international levels as they involve and engage large numbers of stakeholders. Each of these groups has different perspectives and interests in how to design and organize flood risk management, which often hinder transnational collaborations in terms of upstream–downstream or different riverbed cooperation. Numerous efforts to resolve these conflicts have historically been tried across the world, particularly in relation to institutional cooperation. Consequently, greater engagement of different countries in management of natural hazards risks could decrease international conflicts and increase capacity at regional and local levels to adapt to future hazard events. Better understanding of the issues, perspectives, choices, and potential for conflict, and clear sharing of responsibilities, is crucial for reducing impacts of future events at the transboundary level.

Article

Lessons on Risk Governance From the UNISDR Experience  

Sálvano Briceño

In the context of this article, risk governance addresses the ways and means—or institutional framework—to lead and manage the issue of risk related to natural phenomena, events, or hazards, also referred to popularly, although incorrectly, as “natural disasters.” At the present time, risk related to natural phenomena includes a major focus on the issue of climate change with which it is intimately connected, climate change being a major source of risk. To lead involves mainly defining policies and proposing legislation, hence proposing goals, conducting, promoting, orienting, providing a vision—namely, reducing the loss of lives and livelihoods as part of sustainable development—also, raising awareness and educating on the topic and addressing the ethical perspective that motivates and facilitates engagement by citizens. To manage involves, among other things, proposing organizational and technical arrangements, as well as regulations allowing the implementation of policies and legislation. Also, it involves monitoring and supervising such implementation to draw further lessons to periodically enhance the policies, legislation, regulations, and organizational and technical arrangements. UNISDR (now known as UNDRR) was established in 2000 to promote and facilitate risk reduction, becoming in a few years one of the main promoters of risk governance in the world and the main global advocate from within the United Nations system. It was an honor to serve as the first director of the UNISDR (2001–2011). A first lesson to be drawn from this experience was the need to identify, understand, and address the obstacles not allowing the implementation of what seems to be obvious to the scientific community but of difficult implementation by governments, private sector, and civil society; and alternatively, the reasons for shortcomings and weaknesses in risk governance. A second lesson identified was that risk related to natural phenomena also provides lessons for governance related to other types of risk in society—environmental, financial, health, security, and so on, each a separate and specialized topic, sharing, however, common risk governance approaches. A third lesson was the relevance of understanding leadership and management as essential components in governance. Drawing lessons on one’s own experience is always risky as it involves some subjectivity in the analysis. In the article, the aim has, nonetheless, been at the utmost objectivity on the essential learnings in having conducted the United Nations International Strategy for Disaster Reduction—UNISDR—from 2001 to around 2009 when leading and managing was shared with another manager, as I prepared for retirement in 2011. Additional lessons are identified, including those related to risk governance as it is academically conceived, hence, what risk governance includes and how it has been implemented by different international, regional, national, and local authorities. Secondly, I identify those lessons related to the experience of leading and managing an organization focused on disaster risk at the international level and in the context of the United Nations system.

Article

Hydrodynamic Modeling of Urban Flood Flows and Disaster Risk Reduction  

Brett F. Sanders

Communities facing urban flood risk have access to powerful flood simulation software for use in disaster-risk-reduction (DRR) initiatives. However, recent research has shown that flood risk continues to escalate globally, despite an increase in the primary outcome of flood simulation: increased knowledge. Thus, a key issue with the utilization of urban flood models is not necessarily development of new knowledge about flooding, but rather the achievement of more socially robust and context-sensitive knowledge production capable of converting knowledge into action. There are early indications that this can be accomplished when an urban flood model is used as a tool to bring together local lay and scientific expertise around local priorities and perceptions, and to advance improved, target-oriented methods of flood risk communication. The success of urban flood models as a facilitating agent for knowledge coproduction will depend on whether they are trusted by both the scientific and local expert, and to this end, whether the model constitutes an accurate approximation of flood dynamics is a key issue. This is not a sufficient condition for knowledge coproduction, but it is a necessary one. For example, trust can easily be eroded at the local level by disagreements among scientists about what constitutes an accurate approximation. Motivated by the need for confidence in urban flood models, and the wide variety of models available to users, this article reviews progress in urban flood model development over three eras: (1) the era of theory, when the foundation of urban flood models was established using fluid mechanics principles and considerable attention focused on development of computational methods for solving the one- and two-dimensional equations governing flood flows; (2) the era of data, which took form in the 2000s, and has motivated a reexamination of urban flood model design in response to the transformation from a data-poor to a data-rich modeling environment; and (3) the era of disaster risk reduction, whereby modeling tools are put in the hands of communities facing flood risk and are used to codevelop flood risk knowledge and transform knowledge to action. The article aims to inform decision makers and policy makers regarding the match between model selection and decision points, to orient the engineering community to the varied decision-making and policy needs that arise in the context of DRR activities, to highlight the opportunities and pitfalls associated with alternative urban flood modeling techniques, and to frame areas for future research.

Article

Risk and Resilience in the Management and Governance of Natural Hazards  

Christian Kuhlicke

The management of natural hazards is undergoing considerable transformation, including the establishment of risk-based management approaches, the encouragement to govern natural hazards more inclusively, and the rising relevance of the concept of resilience. The benefits of this transformation are usually framed like this: Risk-based approaches are regarded as a rational way of balancing the costs associated with mitigating the consequences of hazards and the anticipated benefits; inclusive modes of governing risks help to increase the acceptance and quality of management processes as well as their outcomes; and the concept of resilience is connoted positively since it demands a greater openness to uncertainties and aims at increasing the capacities of various actors to cope with radical surprises. However, the increasing consideration of both concepts in policy and decision-making processes is associated with a changing demarcation between public and private responsibilities and with an altering relationship between organizations involved in the management process and the wider public. To understand some of these dynamics, this contribution undertakes a change of perspective throughout its development: Instead of asking how the concepts of risk or resilience might be useful to improve the management and governance of natural hazards, one must understand how societies, particularly with regard to their handling of risks and hazards, are governed through the concepts of risk and resilience. Following this perspective, risk-based management approaches have a defensive function in deflecting blame and rationalizing policy choices ex-ante by enabling managing organizations to more clearly define which risks they are responsible for (i.e., non-acceptable risks) and which are beyond their responsibility (i.e., acceptable risks). This demarcation also has profound distributional effects as acceptable risks usually need to be mitigated individually, raising the question of how to ensure the just sharing of the differently distributed benefits and burdens of risk-based approaches. The concept of resilience in this context plays a paradoxical yet complementary role: In its more operational interpretation (e.g., adaptive management), resilience-based management approaches can be in conflict with risk-based approaches as they require those responsible for managing risks to follow antagonistic goals. While the idea of resilience puts an emphasis on openness and flexibility, risk-based approaches try to ensure proportionality by transforming uncertainties into calculable risks. At the same time, resilience-based governance approaches, with their emphasis on self-organization and learning, complement risk-based approaches in the sense that actors or communities that are exposed to “acceptable risks” are implicitly or explicitly made responsible for maintaining their own resilience, whereas the role of public authorities is usually restricted to an enabling one.

Article

Natural Hazards Governance in South Asia  

Mihir Bhatt, Ronak B. Patel, and Kelsey Gleason

South Asia is faced with a range of natural hazards, including floods, droughts, cyclones, earthquakes, landslides, and tsunamis. Rapid and unplanned urbanization, environmental degradation, climate change, and socioeconomic conditions are increasing citizens’ exposure to and risk from natural hazards and resulting in more frequent, intense, and costly disasters. Although governments and the international community are investing in disaster risk reduction, natural hazard governance in South Asian countries remain weak and often warrants a review when a major natural disaster strikes. Natural hazards governance is an emerging concept, and many countries in South Asia have a challenging hazard governance context.

Article

Natural Hazards Governance in Mexico  

Elizabeth Mansilla

As a result of the earthquakes that occurred in September 1985 and their human and material consequences, disaster care in Mexico became institutionalized and acquired the rank of public policy when the first national civil protection law was published years later. More than 30 years after the creation of the National Civil Protection System, there have been some important advances; however, they have not been translated into higher levels of safety for populations exposed to risk. On the contrary, the evidence shows that the country’s risk, as well as the number of disasters and associated material losses, increase year by year. To a large extent, this stems from an approach based predominantly on post-disaster response by strengthening preparedness and emergency response capacities and creating financial mechanisms to address reconstruction processes, as opposed to broader approaches seeking to address the root causes of risk and disasters. Post-disaster actions and reconstruction processes have failed to achieve acceptable levels of efficiency, and disorganization and misuse of resources that should benefit disaster-affected populations still prevails.

Article

Debris-Flow Risk Assessment  

Matthias Jakob, Kris Holm, and Scott McDougall

Debris flows are one of the most destructive landslide processes worldwide, given their ubiquity in mountainous areas occupied by human settlement or industrial facilities around the world. Given the episodic nature of debris flows, these hazards are often un- or under-recognized. Three fundamental components of debris-flow risk assessments include frequency-magnitude analysis, numerical scenario modeling, and consequence analysis to estimate the severity of damage and loss. Recent advances in frequency-magnitude analysis take advantage of developments in methods to estimate the age of deposits and size of past and potential future events. Notwithstanding, creating reliable frequency-magnitude relationships is often challenged by practical limitations to investigate and statistically analyze past debris-flow events that are often discontinuous, as well as temporally and spatially censored. To estimate flow runout and destructive potential, several models are used worldwide. Simple empirical models have been developed based on statistical geometric correlations, and two-dimensional and three-dimensional numerical models are commercially available. Quantitative risk assessment (QRA) methods for assessing public safety were developed for the nuclear industry in the 1970s and have been applied to landslide risk in Hong Kong starting in 1998. Debris-flow risk analyses estimate the likelihood of a variety of consequences. Quantitative approaches involve prediction of the annual probability of loss of life to individuals or groups and estimates of annualized economic losses. Recent progress in quantitative debris-flow risk analyses include improved methods to characterize elements at risk within a GIS environment and estimates of their vulnerability to impact. Improvements have also been made in how these risks are communicated to decision makers and stakeholders, including graphic display on conventional and interactive online maps. Substantial limitations remain, including the practical impossibility of estimating every direct and indirect risk associated with debris flows and a shortage of data to estimate vulnerabilities to debris-flow impact. Despite these limitations, quantitative debris-flow risk assessment is becoming a preferred framework for decision makers in some jurisdictions, to compare risks to defined risk tolerance thresholds, support decisions to reduce risk, and quantify the residual risk remaining following implementation of risk reduction measures.

Article

Flood Insurance and Flood Risk Reduction  

Swenja Surminski

The rapid increase in losses from flooding underlines the importance of risk reduction efforts to prevent or at least mitigate the damaging impacts that floods can bring to communities, businesses, and countries. This article provides an overview of how the science of disaster risk management has improved understanding of pre-event risk reduction [or disaster risk reduction (DRR)]. Implementation, however, is still lagging, particularly when compared to expenditure for recovery and repair after a flood event. In response, flood insurance is increasingly being suggested as a potential lever for risk reduction, despite concerns about moral hazard. The article considers the literature that has emerged on this topic and discusses if the conceptual efforts of linking flood insurance and risk reduction have led to practical action. Overall, there is limited evidence of flood insurance effectively promoting risk reduction. To the extent there is, it suggests that more complex behavioral aspects are also at play. Further evidence is required to support this potential role, particularly around data and risk assessment, and the viability of different risk reduction measures.

Article

Linking Risk Reduction and Community Resilience  

Hyunjung Ji

Risk reduction is a policy priority in governments at all levels. Building community resilience is one of the keys to reducing disaster risks. Resilience-focused risk reduction considers the wider social, political, and cultural environments of a community and emphasizes the importance of working with community members. This is in stark contrast to the previous vulnerability-focused risk management that treats disasters as unavoidable natural events and recognizes people as passive or helpless under the unavoidable disasters. Community resilience is a critical concept in identifying visions and directions for risk reduction strategies. Community resilience has two major qualities: inherent community conditions (inherent resilience) and the community’s adaptive capacity (adaptive resilience). There are at least four components that should be included in risk reduction strategies to enhance both inherent and adaptive community resilience: risk governance, community-based risk reduction policies, non-governmental disaster entrepreneurs, and people-centered risk reduction measures. Risk governance is required to bridge the gap between national policies and local practices, scientific knowledge of natural hazards and locally accumulated knowledge, and national assistance and local actions. Community-based risk reduction policies should complement national disaster policies to reflect locally specific patterns of hazard, exposure, and resilience that are otherwise ignored in policy design process at the international and national levels. Risk reduction strategies should also encourage emergence of non-governmental entrepreneurs who can contribute to the speed and success of community relief and recovery following a disaster by resolving the immediate needs of the affected communities and transitioning people toward autonomy and self-reliance. Finally, risk reduction strategies should include people-centered policy measures that are designed to change the awareness, attitudes, and behaviors of people so that they are more prepared when facing a disaster.

Article

Assessment and Adaptation to Climate Change-Related Flood Risks  

Brenden Jongman, Hessel C. Winsemius, Stuart A. Fraser, Sanne Muis, and Philip J. Ward

The flooding of rivers and coastlines is the most frequent and damaging of all natural hazards. Between 1980 and 2016, total direct damages exceeded $1.6 trillion, and at least 225,000 people lost their lives. Recent events causing major economic losses include the 2011 river flooding in Thailand ($40 billion) and the 2013 coastal floods in the United States caused by Hurricane Sandy (over $50 billion). Flooding also triggers great humanitarian challenges. The 2015 Malawi floods were the worst in the country’s history and were followed by food shortage across large parts of the country. Flood losses are increasing rapidly in some world regions, driven by economic development in floodplains and increases in the frequency of extreme precipitation events and global sea level due to climate change. The largest increase in flood losses is seen in low-income countries, where population growth is rapid and many cities are expanding quickly. At the same time, evidence shows that adaptation to flood risk is already happening, and a large proportion of losses can be contained successfully by effective risk management strategies. Such risk management strategies may include floodplain zoning, construction and maintenance of flood defenses, reforestation of land draining into rivers, and use of early warning systems. To reduce risk effectively, it is important to know the location and impact of potential floods under current and future social and environmental conditions. In a risk assessment, models can be used to map the flow of water over land after an intense rainfall event or storm surge (the hazard). Modeled for many different potential events, this provides estimates of potential inundation depth in flood-prone areas. Such maps can be constructed for various scenarios of climate change based on specific changes in rainfall, temperature, and sea level. To assess the impact of the modeled hazard (e.g., cost of damage or lives lost), the potential exposure (including buildings, population, and infrastructure) must be mapped using land-use and population density data and construction information. Population growth and urban expansion can be simulated by increasing the density or extent of the urban area in the model. The effects of floods on people and different types of buildings and infrastructure are determined using a vulnerability function. This indicates the damage expected to occur to a structure or group of people as a function of flood intensity (e.g., inundation depth and flow velocity). Potential adaptation measures such as land-use change or new flood defenses can be included in the model in order to understand how effective they may be in reducing flood risk. This way, risk assessments can demonstrate the possible approaches available to policymakers to build a less risky future.

Article

Flood Resilient Construction and Adaptation of Buildings  

David Proverbs and Jessica Lamond

Flood resilient construction has become an essential component of the integrated approach to flood risk management, now widely accepted through the concepts of making space for water and living with floods. Resilient construction has been in place for centuries, but only fairly recently has it been recognized as part of this wider strategy to manage flood risk. Buildings and the wider built environment are known to play a key role in flood risk management, and when buildings are constructed on or near to flood plains there is an obvious need to protect these. Engineered flood defense systems date back centuries, with early examples seen in China and Egypt. Levees were first built in the United States some 150 years ago, and were followed by the development of flood control acts and regulations. In 1945, Gilbert Fowler White, the so-called “father of floodplain management,” published his influential thesis which criticized the reliance on engineered flood defenses and began to change these approaches. In Europe, a shortage of farmable land led to the use of land reclamation schemes and the ensuing Land Drainage acts before massive flood events in the mid-20th century led to a shift in thinking towards the engineered defense schemes such as the Thames Barrier and Dutch dyke systems. The early 21st century witnessed the emergence of the “living with water” philosophy, which has resulted in the renewed understanding of flood resilience at a property level. The scientific study of construction methods and building technologies that are robust to flooding is a fairly recent phenomenon. There are a number of underlying reasons for this, but the change in flood risk philosophy coupled with the experience of flood events and the long process of recovery is helping to drive research and investment in this area. This has led to a more sophisticated understanding of the approaches to avoiding damage at an individual property level, categorized under three strategies, namely avoidance technology, water exclusion technology, and water entry technology. As interest and policy has shifted to water entry approaches, alongside this has been the development of research into flood resilient materials and repair and reinstatement processes, the latter gaining much attention in the recognition that experience will prompt resilient responses and that the point of reinstatement provides a good opportunity to install resilient measures. State-of-the-art practices now center on avoidance strategies incorporating planning legislation in many regions to prohibit or restrict new development in flood plains. Where development pressures mean that new buildings are permitted, there is now a body of knowledge around the impact of flooding on buildings and flood resilient construction and techniques. However, due to the variety and complexity of architecture and construction styles and varying flood risk exposure, there remain many gaps in our understanding, leading to the use of trial and error and other pragmatic approaches. Some examples of avoidance strategies include the use of earthworks, floating houses, and raised construction. The concept of property level flood resilience is an emerging concept in the United Kingdom and recognizes that in some cases a hybrid approach might be favored in which the amount of water entering a property is limited, together with the likely damage that is caused. The technology and understanding is moving forward with a greater appreciation of the benefits from combining strategies and property level measures, incorporating water resistant and resilient materials. The process of resilient repair and considerate reinstatement is another emerging feature, recognizing that there will be a need to dry, clean, and repair flood-affected buildings. The importance of effective and timely drying of properties, including the need to use materials that dry rapidly and are easy to decontaminate, has become more apparent and is gaining attention. Future developments are likely to concentrate on promoting the uptake of flood resilient materials and technologies both in the construction of new and in the retrofit and adaptation of existing properties. Further development of flood resilience technology that enhances the aesthetic appeal of adapted property would support the uptake of measures. Developments that reduce cost or that offer other aesthetic or functional advantages may also reduce the barriers to uptake. A greater understanding of performance standards for resilient materials will help provide confidence in such measures and support uptake, while further research around the breathability of materials and concerns around mold and the need to avoid creating moisture issues inside properties represent some of the key areas.

Article

Flood Risk Analysis  

Bruno Merz

Floods affect more people worldwide than any other natural hazard. Flood risk results from the interplay of a range of processes. For river floods, these are the flood-triggering processes in the atmosphere, runoff generation in the catchment, flood waves traveling through the river network, possibly flood defense failure, and finally, inundation and damage processes in the flooded areas. In addition, ripple effects, such as regional or even global supply chain disruptions, may occur. Effective and efficient flood risk management requires understanding and quantifying the flood risk and its possible future developments. Hence, risk analysis is a key element of flood risk management. Risk assessments can be structured according to three questions: What can go wrong? How likely is it that it will happen? If it goes wrong, what are the consequences? Before answering these questions, the system boundaries, the processes to be included, and the detail of the analysis need to be carefully selected. One of the greatest challenges in flood risk analyses is the identification of the set of failure or damage scenarios. Often, extreme events beyond the experience of the analyst are missing, which may bias the risk estimate. Another challenge is the estimation of probabilities. There are at most a few observed events where data on the flood situation, such as inundation extent, depth, and loss are available. That means that even in the most optimistic situation there are only a few data points to validate the risk estimates. The situation is even more delicate when the risk has to be quantified for important infrastructure objects, such as breaching of a large dam or flooding of a nuclear power plant. Such events are practically unrepeatable. Hence, estimating of probabilities needs to be based on all available evidence, using observations whenever possible, but also including theoretical knowledge, modeling, specific investigations, experience, or expert judgment. As a result, flood risk assessments are often associated with large uncertainties. Examples abound where authorities, people at risk, and disaster management have been taken by surprise due to unexpected failure scenarios. This is not only a consequence of the complexity of flood risk systems, but may also be attributed to cognitive biases, such as being overconfident in the risk assessment. Hence, it is essential to ask: How wrong can the risk analysis be and still guarantee that the outcome is acceptable?

Article

Changing Disaster Vulnerability and Capability in Aging Populations  

Jennifer Whytlaw and Nicole S. Hutton

The aging population, also referred to as elderly or seniors, represents a demographic of growing significance for disaster management. The population pyramid, an important indicator of population growth, stability, and decline, has shifted from the typical pyramid shape into more of a dome shape when viewing trends globally. While these demographic shifts in age structure are unique to individual countries, adjustments in disaster management are needed to reduce the risk of aging populations increasingly affected by hazards. Risk is especially evident when considering where aging populations live, as proximity to environmental hazards such as flooding, tropical storm surge, fires, and extreme weather resulting in heat and cold increase their risk. Aging populations may live alone or together in retirement communities and senior living facilities where the respective isolation or high density of older adults present specific risks. There is a concern in areas with high economic productivity, also considered post-industrial areas, where the population consists more of those who are aging and less of those who are younger to support the labor needs of the market and more specifically to support and engage aging populations. This disparity becomes even more prominent in specific sectors such as healthcare, including senior living assistance. In developing economies, the young are increasingly leaving traditionally intergenerational households to seek greater economic opportunities in cities, leaving many seniors on their own. Thus, risk reduction strategies must be conscious of the needs and contributions of seniors as well as the capacity of the workforce to implement them. The integration of aging populations within disaster management through accommodation and consultation varies across the globe. Provision of services for and personal agency among senior populations can mitigate vulnerabilities associated with age, as well as compounding factors such as medical fragility, societal interaction, and income. Experience, mobility, and socioeconomic capabilities affect decision making and outcomes of aging populations in hazardous settings. Therefore, the means of involvement in disaster planning should be adapted to accommodate the sociocultural, economic, and environmental realities of aging populations.

Article

Linking Hazard Vulnerability, Risk Reduction, and Adaptation  

Jörn Birkmann and Joanna M. McMillan

The concepts of vulnerability, disaster risk reduction and climate change adaptation are interlinked. Risk reduction requires a focus not just on the hazards themselves or on the people and structures exposed to hazards but on the vulnerability of those exposed. Vulnerability helps with the identification of root causes that make people or structures susceptible to being affected by natural and climate-related hazards. It is therefore an essential component of reducing risk of disasters and of adapting to climate change. The need to better assess and acknowledge vulnerability has been recognized by several communities of thought and practice, including the Disaster Risk Reduction (DRR) and Climate Change Adaptation (CCA) communities. The concept of vulnerability was introduced during the 1980s as a way to better understand the differential consequences of similar hazard events and differential impacts of climate change on different societies or social groups and physical structures. Since then, the concept gradually became an integral part of discourses around disaster risk reduction and climate change adaptation. Although the history of the emergence of vulnerability concepts and the different perspectives of these communities mean the way they frame vulnerability differs, the academic discourse has reached wide agreement that risk—and actual harm and losses—are not just caused by physical events apparently out of human control but primarily by what is exposed and vulnerable to those events. In the international policy arena, vulnerability, risk, and adaptation concepts are now integrated into the global agenda on sustainable development, disaster risk reduction, and climate change. In the context of international development projects and financial aid, the terms and concepts are increasingly used and applied. However, there is still too little focus on addressing underlying vulnerabilities.

Article

Readiness for Natural Hazards  

Douglas Paton

Humankind has always lived with natural hazards and their consequences. While the frequency and intensity of geological processes may have remained relatively stable, population growth and infrastructure development in areas susceptible to experiencing natural hazards has increased societal risk and the losses experienced from hazard activity. Furthermore, increases in weather-related (e.g., hurricanes, wildfires) hazards emanating from climate change will increase risk in some countries and result in others having to deal with natural hazard risk for the first time. Faced with growing and enduring risk, disaster risk reduction (DRR) strategies will play increasingly important roles in facilitating societal sustainability. This article discusses how readiness or preparedness makes an important contribution to comprehensive DRR. Readiness is defined here in terms of those factors that facilitate people’s individual and collective capability to anticipate, cope with, adapt to, and recover from hazard consequences. This article first discusses the need to conceptualize readiness as comprising several functional categories (structural, survival/direct action, psychological, community/capacity building, livelihood and community-agency readiness). Next, the article discusses how the nature and extent of people’s readiness is a function of the interaction between the information available and the personal, family, community and societal factors used to interpret information and support readiness decision-making. The health belief model (HBM), protection motivation theory (PMT), person-relative-to-event (PrE) theory, theory of planned behavior (TPB), critical awareness (CA), protective action decision model (PADM), and community engagement theory (CET) are used to introduce variables that inform people’s readiness decision-making. A need to consider readiness as a developmental process is discussed and identifies how the variables introduced in the above theories play different roles at different stages in the development of comprehensive readiness. Because many societies must learn to coexist with several sources of hazard, an “all-hazards” approach is required to facilitate the capacity of societies and their members to be resilient in the face of the various hazard consequences they may have to contend with. This article discusses research into readiness for the consequences that arise from earthquake, volcanic, flood, hurricane, and tornado hazards. Furthermore, because hazards transcend national and cultural divides, a comprehensive conceptualization of readiness must accommodate a cross-cultural perspective. Issues in the cross-cultural testing of theory is discussed, as is the need for further work into the relationship between readiness and culture-specific beliefs and processes.

Article

Challenges for Natural Hazard and Risk Management in Mountain Regions of Europe  

Margreth Keiler and Sven Fuchs

European mountain regions are diverse, from gently rolling hills to high mountain areas, and from low populated rural areas to urban regions or from communities dependent on agricultural productions to hubs of tourist industry. Communities in European mountain regions are threatened by different hazard types: for example floods, landslides, or glacial hazards, mostly in a multi-hazard environment. Due to climate change and socioeconomic developments they are challenged by emerging and spatially as well as temporally highly dynamic risks. Consequently, over decades societies in European mountain ranges developed different hazard and risk management strategies on a national to local level, which are presented below focusing on the European Alps. Until the late 19th century, the paradigm of hazard protection was related to engineering measures, mostly implemented in the catchments, and new authorities responsible for mitigation were founded. From the 19th century, more integrative strategies became prominent, becoming manifest in the 1960s with land-use management strategies targeted at a separation of hazardous areas and areas used for settlement and economic purpose. In research and in the application, the concept of hazard mitigation was step by step replaced by the concept of risk. The concept of risk includes three components (or drivers), apart from hazard analysis also the assessment and evaluation of exposure and vulnerability; thus, it addresses in the management of risk reduction all three components. These three drivers are all dynamic, while the concept of risk itself is thus far a static approach. The dynamic of risk drivers is a result of both climate change and socioeconomic change, leading through different combinations either to an increase or a decrease in risk. Consequently, natural hazard and risk management, defined since the 21st century using the complexity paradigm, should acknowledge such dynamics. Moreover, researchers from different disciplines as well as practitioners have to meet the challenges of sustainable development in the European mountains. Thus, they should consider the effects of dynamics in risk drivers (e.g., increasing exposure, increasing vulnerability, changes in magnitude, and frequency of hazard events), and possible effects on development areas. These challenges, furthermore, can be better met in the future by concepts of risk governance, including but not limited to improved land management strategies and adaptive risk management.