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Disasters are significant events with enormous consequences for democratic political systems. As such, they provide important insights into how governmental institutions address hazardous situations. They also reveal the critical role that the media and politics play in this process. These themes are echoed in the general research on disasters, as well as in the accounts of hazardous events occurring in specific communities and locales. However, despite the wealth of scholarship conducted on this topic across a variety of disciplines, important questions remain about what role citizens play in this process, as well as the impact of governmental hazard management policies on broader democratic processes and societal conditions.
Emergency and disaster planning involves a coordinated, co-operative process of preparing to match urgent needs with available resources. The phases are research, writing, dissemination, testing, and updating. Hence, an emergency plan needs to be a living document that is periodically adapted to changing circumstances and that provides a guide to the protocols, procedures, and division of responsibilities in emergency response. Emergency planning is an exploratory process that provides generic procedures for managing unforeseen impacts and should use carefully constructed scenarios to anticipate the needs that will be generated by foreseeable hazards when they strike. Plans need to be developed for specific sectors, such as education, health, industry, and commerce. They also need to exist in a nested hierarchy that extends from the local emergency response (the most fundamental level), through the regional tiers of government, to the national and international levels. Failure to plan can be construed as negligence because it would involve failing to anticipate needs that cannot be responded to adequately by improvisation during an emergency.
Plans are needed, not only for responding to the impacts of disaster, but also to maintain business continuity while managing the crisis, and to guide recovery and reconstruction effectively. Dealing with disaster is a social process that requires public support for planning initiatives and participation by a wide variety of responders, technical experts and citizens. It needs to be sustainable in the light of challenges posed by non-renewable resource utilization, climate change, population growth, and imbalances of wealth. Although, at its most basic level, emergency planning is little more than codified common sense, the increasing complexity of modern disasters has required substantial professionalization of the field. This is especially true in light of the increasing role in emergency response of information and communications technology. Disaster planners and coordinators are resource managers, and in the future, they will need to cope with complex and sophisticated transfers of human and material resources. In a globalizing world that is subject to accelerating physical, social, and economic change, the challenge of managing emergencies well depends on effective planning and foresight, and the ability to connect disparate elements of the emergency response into coherent strategies.
As an urbanized river-dominated delta, New Orleans, Louisiana, ranks among the most experimental of cities, a test of whether the needs of a stable human settlement can coexist with the fluidity of a deltaic environment—and what happens when they do not.
That natural environment bestowed upon New Orleans numerous advantages, among them abundant fresh water, fertile soils, productive wetlands and, above all, expedient passage between maritime and continental realms. But with those advantages came exposure to potential hazards—an overflowing Mississippi River, a tempestuous Gulf of Mexico, sinking soils, eroding coasts, rising seas, biotic invasion, pestilence, political and racial discord, conflagration—made all the worse by the high levels of social vulnerability borne by all too many members of New Orleans’ population. More so than any other major metropolis on the North American continent, this history of disaster and response is about the future of New Orleans as much as it is about the past.
This article examines two dozen disasters of various types and scales, with origins oftentimes traceable to anthropogenic manipulation of the natural environment, and assesses the nature of New Orleans’ responses. It frames these assessments in the “risk triangle” framework offered by David Crichton and other researchers, which views urban risk as a function of hazard, exposure, and vulnerability. “Hazard” implies the disastrous event or trauma itself; “exposure” means human proximity to the hazard, usually in the form of settlement patterns, and “vulnerability” indicates individuals’ and communities’ ability to respond resiliently and adaptively—which itself is a function of education, income, age, race, language, social capital, and other factors—after having been exposed to a hazard.
Thomas Husted and David Nickerson
Natural disasters pose a significant and rapidly growing burden to society, causing over a million deaths and worldwide economic losses in the trillions of dollars in the last twenty years. Concerned over the extent to which their populations are exposed to disaster risk, policymakers in disaster-prone countries strive to increase the penetration of disaster insurance from its relatively low current level and wish to arrest the increasing share of public liability for private losses arising from rising public expenditures on disaster recovery.
Although evidence regarding disaster risk and insurance suggests that individuals respond to their economic incentives when deciding on the degree to which to expose their property and other to risk from a recurrent disaster, potential inefficiencies in private insurance markets can distort these individual incentives and result in underinsurance and excessive exposure. Current research into whether such apparent market inefficiencies are primarily attributed to the behavior of private market participants or to the adverse incentives arising from current programs of disaster aid, regulation and other public policies is of fundamental importance to attaining these policy objectives.
This article critically assesses the current state of mainstream economic and political research into disasters, public policy, and household behavior toward disaster risk. Findings of the most important and influential empirical and theoretical studies over the last 30 years are described, as well as limits on the robustness and interpretation of these findings arising from the characteristics of economic data on disasters and potential bias in measuring the determinants of disaster insurance coverage. Also discussed are both theoretical and empirical evidence that moral hazard on the part of households, insurance firms, and elected officials results in misallocations of private coverage; and it is demonstrated that, exactly contrary to the objectives of public policy, current programs of disaster aid in the presence of moral hazard create incentives for households to minimize, rather than maximize, market coverage of their exposure to disaster risk. The conclusion presents and proves a proposition, original to this article, that any compensatory public aid program is necessarily a source of economic inefficiency and, conditional on net losses, decreases economic welfare.
Mihir Bhatt, Ronak B. Patel, Kelsey Gleason, and Mehul Pandya
Both the impact and the frequency of natural disasters and extreme events in South Asia are steadily increasing due to growing exposure and vulnerability. These vulnerabilities are compounded by fast economic growth and an increase in natural disasters across the region. Disaster losses in South Asia are rising and are felt across many domains. From the formal to the informal economy, natural disasters have increasingly strong impacts in terms of lives lost, social impact, and impediments to growth. New challenges in disaster risk reduction are emerging due to an increase in the duration and frequency of natural disaster events attributable to climate change. Though both climate change adaptation and disaster risk reduction efforts exist to some degree throughout South Asia, integrating climate change adaptation into disaster risk reduction is critical to successful and inclusive growth of economies in the region. Challenges remain, and national and subnational governments are making some progress in policies aimed at both climate change adaptation and disaster risk reduction. However, many of these efforts are planned, designed, and implemented separately, with limited understanding of how disaster and climate risk are linked. Moreover, progress is hindered by poor understanding of how integration of these concepts can result in better governance of risk in South Asia. Additionally, political will, capacity constraints, and institutional barriers must be overcome. Efforts by the international community are making progress in unifying these concepts, yet gaps and challenges still exist. The benefits of converging climate adaptation and disaster risk reduction in Asia are significant, from minimizing climate-related losses to more efficient use of limited resources and more effective and sustainable development.
Large-scale displacement takes place in the context of disaster because the threat or occurrence of hazard onset makes the region of residence of a population uninhabitable, either temporarily or permanently. Contributing to that outcome, the wide array of disaster events is invariably complicated by human institutions and practices that can contribute to large-scale population displacements. Growing trends of socially driven exposure and vulnerability around the world as well as the global intensification and frequency of climate-related hazards have increased both the incidence and the likelihood of large-scale population dislocations in the near future. However, legally binding international and national accords and conventions have not yet been put in place to deal with the serious impacts, and material, health-related, and sociocultural losses and human rights violations that are experienced by the millions of people being swept up in the events and processes of disasters and mass population displacements. Effective policy development is challenged by the increasing complexity of disaster risk and occurrence as well as issues of causation, adequate information, lack of capacity, and legal responsibility. States, international organizations, state and international development and aid agencies must frame, define, and categorize appropriately disaster forced displacement and resettlement to influence effective institutional responses in emergency humanitarian assistance, transitional shelter and care, and durable solutions in managing migration and resettlement if return is not possible. The forms that disaster-associated forced displacements are projected to take and corresponding national responses are explored in the Indian Ocean tsunami of 2004 in Sri Lanka, a massive disaster in a nation riven by civil conflict; Hurricane Katrina of 2005 in the United States, where the scale and nature of displacement bore little relation to hazard intensity; and the 2011 Great East Japan Earthquake, Tsunami, and nuclear exposure incident exemplifying the emerging trend of complex, concatenating, multihazard disasters that bring about large-scale population displacements.
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Natural Hazard Science. Please check back later for the full article.
Emergency managers, community leaders, and organizations can recruit and deploy volunteers to make a difference when disasters occur. Leveraging the social capital such volunteers produce can expedite disaster response and recovery if managed effectively. Recent research brings to light the benefits and consequences of volunteerism, including the personal meaningfulness found in disaster service. Evidence-based best practices for organizing, recruiting, preparing, deploying, and debriefing volunteers inform those who seek to understand and use volunteers. Disaster volunteers may be spontaneous unaffiliated volunteers (SUVs) or affiliated with experienced organizations. The benefits each can provide vary. Trends that have influenced today’s disaster volunteers include the professionalization of disaster voluntary organizations, training and education, and social media. The development of inter-organizational partnerships represents one such trend, particularly the National Voluntary Organizations Active in Disaster (NVOAD) movement toward Points of Consensus on volunteer management. Cases illustrating turning points in the history of disaster volunteerism and trends over time in the United States can be drawn from the Johnstown flood (1889), the Galveston hurricane (1900), the San Francisco earthquake (1906), hurricane Camille (1969), the Mississippi River floods, hurricane Katrina (2005), and SuperStorm Sandy (2012). Internationally, examples of best practices can be drawn from the research and experiences in the Indian Ocean tsunami (2004), the Haiti earthquake (2010), and Japan’s multiple, cascading events of 2011.
The immediate aftermath of a great urban earthquake is a dramatic and terrible event, comparable to a massive terrorist attack. Yet the shocking impact soon fades from the public mind and receives surprisingly little attention from historians, unlike wars and human atrocities. In 1923, the Great Kanto earthquake and its subsequent fires demolished most of Tokyo and Yokohama and killed around 140,000 Japanese: a level of devastation and fatalities comparable with the atomic bombing of Hiroshima and Nagasaki in 1945. But the second event has infinitely more resonance in public consciousness and historical studies than the first. Indeed, most people would be challenged to name a single earthquake with an indisputable historical impact, including even the most famous of all earthquakes: the San Francisco earthquake and fire of 1906.
In truth, however, great earthquakes, from ancient times—as recorded by Greek and biblical writers—to the present day, have had major cultural, economic, and political consequences—often a combination of all three—some of which were beneficial. Thus, the current prime minister of India owes his election in 2014 to an earthquake that devastated part of his home state of Gujarat in 2001, which led to its striking economic growth. The martial law imposed on Tokyo and Yokohama after the 1923 earthquake gave new authority to the Japanese army, which eventually took over the Japanese government and led Japan to war with China and the world. The destruction of San Francisco in 1906 produced a boom in rebuilding and financial and technological development of the surrounding area on the San Andreas Fault, including what became Silicon Valley. A great earthquake in Venezuela in 1812 was the principal cause of the temporary defeat of its leader Simon Bolivar by the Spanish colonial regime, but his subsequent exile led to his permanent freeing of Bolivia, Colombia, Ecuador, Peru, and Venezuela from Spanish rule. The catastrophic Lisbon earthquake of 1755—as well known in the early 19th century as the 1945 atomic bombings are today—was a pivotal factor in the freeing of Enlightenment science from Catholic religious orthodoxy, as epitomized by Voltaire’s satirical novel Candide, written in response to the earthquake. Even the minor earthquakes in Britain in 1750, the so-called Year of Earthquakes, produced the earliest scientific understanding of earthquakes, published by the Royal Society: the beginning of seismology.
The long-term impact of a great earthquake depends on its epicenter, magnitude, and timing—and also on human factors: the political, social, intellectual, religious, and cultural resources specific to a region’s history. Each earthquake-struck society offers its own particular lesson, and yet, taken together, such earth-shattering events have important shared consequences for the history of the world.
Joanne Stevenson, Ilan Noy, Garry McDonald, Erica Seville, and John Vargo
The economics of disasters is a relatively new and emerging branch of economics. Advances made in analysis, including modeling the spatial economic impacts of disasters, is increasing our ability to project disaster outcomes and explore how to reduce their negative impacts. This work is supported by a growing body of case studies on the organizational and economic impacts of disasters, such as Chang’s in-depth analysis of the Port of Kobe’s decline following the 1995 Great Hanshin earthquake, and the evolving studies of the workforce trends during the ongoing recovery of Christchurch, New Zealand, following a series of earthquakes in 2010 and 2011.
The typical view of post-disaster economies depicts a pattern of destruction, renewal, and improvement. Evidence shows, however, that this pattern does not occur in all cases. The degree of economic disruption and the time it takes for different economies to recover varies significantly depending on characteristics such as literacy rates, institutional competency, per capita income, and government spending.
If the impacts are large relative to the national economy, a disaster can negatively affect the country or sub-national region’s fiscal position. Similarly, disasters may have significant implications for the national trade balance. If, for example, productive capacity is reduced by disaster damage, exports decrease, the trade balance may weaken, and localized inflation may increase.
Studies of individual, household, industry, and business responses to disasters (i.e., microeconomic analyses) cover a broad range of topics relevant to the choices actors make and their interactions with markets. Both household consumption and labor markets face expansion and contraction in areas affected by disasters, with increased consumption and employment often happening in reconstruction related industries.
Additionally, the ability of businesses to absorb, respond, and recover in the face of disasters varies widely. Characteristics such as size, number of locations, and pre-disaster financial health are positively correlated with successful business recovery. Businesses can minimize productivity disruptions and recapture lost productivity by conserving scarce inputs, utilizing inventories, and rescheduling production.
Assessing the progress of economic recovery and predicting future outcomes are important and complex challenges. Researchers use various methodologies to evaluate the effects of natural disasters at different scales of the economy. Surveys, microeconomic models, econometric models, input-output models, and computable general equilibrium models each offer different insights into the effect of disasters on economies.
The study of disaster economics still faces issues with consistency, comprehensiveness, and comparability. Yet, as the science continues to advance there is a growing cross-disciplinary accumulation of knowledge with real implications for policy and the private sector.
Evolution of Strategic Flood Risk Management in Support of Social Justice, Ecosystem Health, and Resilience
Throughout history, flood management practice has evolved in response to flood events. This heuristic approach has yielded some important incremental shifts in both policy and planning (from the need to plan at a catchment scale to the recognition that flooding arises from multiple sources and that defenses, no matter how reliable, fail). Progress, however, has been painfully slow and sporadic, but a new, more strategic, approach is now emerging.
A strategic approach does not, however, simply sustain an acceptable level of flood defence. Strategic Flood Risk Management (SFRM) is an approach that relies upon an adaptable portfolio of measures and policies to deliver outcomes that are socially just (when assessed against egalitarian, utilitarian, and Rawlsian principles), contribute positively to ecosystem services, and promote resilience. In doing so, SFRM offers a practical policy and planning framework to transform our understanding of risk and move toward a flood-resilient society. A strategic approach to flood management involves much more than simply reducing the chance of damage through the provision of “strong” structures and recognizes adaptive management as much more than simply “wait and see.” SFRM is inherently risk based and implemented through a continuous process of review and adaptation that seeks to actively manage future uncertainty, a characteristic that sets it apart from the linear flood defense planning paradigm based upon a more certain view of the future.
In doing so, SFRM accepts there is no silver bullet to flood issues and that people and economies cannot always be protected from flooding. It accepts flooding as an important ecosystem function and that a legitimate ecosystem service is its contribution to flood risk management. Perhaps most importantly, however, SFRM enables the inherent conflicts as well as opportunities that characterize flood management choices to be openly debated, priorities to be set, and difficult investment choices to be made.
Deserai A. Crow
As with countless other policy areas, natural hazard policy can be viewed as a jurisdictional competition between executive and legislative branches. While policymaking supremacy is delegated to the legislative branch in constitutional democracies, the power over implementation, budgeting, and grant-making that executive agencies enjoy means that the executive branch wields considerable influence over outcomes in natural hazards policymaking. The rules that govern federal implementation of complex legislative policies put the implementing agency at the center of influence over how policy priorities play out in local, county, and state processes before, during, and after disasters hit.
Examples abound related to this give-and-take between the legislative and executive functions of government within the hazards and disaster realm, but none more telling than the changes made to US disaster policy after September 11th, which profoundly affected natural hazards policy as well as security policy. The competition and potential for mismatch between legislative and executive priorities has been heightened since the Federal Emergency Management Agency (FEMA) was reorganized under the Department of Homeland Security. While this may appear uniquely American, the primacy of terrorism and other security-related threats not only dwarfs natural hazards issues in the United States, but also globally. Among the most professionalized and powerful natural hazards and disaster agencies prior to 9/11, FEMA has seen its influence diminished and its access to decision-makers reduced.
This picture of legislative and executive actors within the natural hazards policy domain who compete for supremacy goes beyond the role of FEMA and post-9/11 policy. Power dynamics associated with budgets, oversight and accountability, and relative power among executive agencies are ongoing issues important to understanding the competition for policy influence as natural hazards policy competes for attention, funding, and power within the broader domain of all-hazards policy.
Fatalism about natural disasters hinders action to prepare for those disasters, and overcoming this fatalism is one key element to preparing people for these disasters. Research by Bostrom and colleagues shows that failure to act often reflects gaps and misconceptions in citizen’s mental models of disasters. Research by McClure and colleagues shows that fatalistic attitudes reflect people’s attributing damage to uncontrollable natural causes rather than controllable human actions, such as preparation. Research shows which precise features of risk communications lead people to see damage as preventable and to attribute damage to controllable human actions. Messages that enhance the accuracy of mental models of disasters by including human factors recognized by experts lead to increased preparedness. Effective messages also communicate that major damage in disasters is often distinctive and reflects controllable causes. These messages underpin causal judgments that reduce fatalism and enhance preparation. Many of these messages are not only beneficial but also newsworthy. Messages that are logically equivalent but are differently framed have varying effects on risk judgments and preparedness. The causes of harm in disasters are often contested, because they often imply human responsibility for the outcomes and entail significant cost.
Charlotte L. Kirschner, Akheil Singla, and Angie Flick
As more and more of the population moves to areas prone to natural hazards, the costs of disasters are on the rise. Given that these events are an eventuality, governments must aid their communities in promoting disaster resilience, enabling their communities to reduce their susceptibility to natural hazards, and adapting to and recovering from disasters when they occur.
The federal system in the United States divides these responsibilities among national, state, and local governments. Local and state governments are largely responsible for the direct provision of services to their communities, and the Stafford Act of 1988 provides that the federal government will pay at least 75% of all eligible expenses once a presidential major disaster declaration has been made. As a result, state and local governments have become largely reliant on transfers from the federal government to pay for disaster relief and recovery efforts. This system encourages state and local governments to ignore the risks they face and turn to the federal government for aid after a disaster.
This system also seems to underemphasize an important mechanism that can bolster disaster resilience: financing the costs of disasters in advance through ex ante budgeting. Four tools for budgeting ex ante—intergovernmental grants, disaster stabilization funds, the municipal bond market, and hazard insurance—are described and examples of their use provided. Despite limited use by state governments, these tools provide governments the opportunity to build community resilience to disasters by budgeting ex ante for them.
Natural disasters cause massive social disruptions and can lead to tremendous economic and human losses. Given their uncertain and destructive nature, disasters invariably induce significant governmental responses and typically pose severe financial challenges for jurisdictions across all levels of government. From a public finance perspective, disasters cause governments to incur additional spending on various emergency management activities, and by disrupting normal business activities they also affect tax base robustness and cause revenue losses. The question is: How significant are these fiscal effects and how do they affect hazards governance more generally? Understanding the fiscal implications of natural disasters is essential to evaluating the size of the economic costs of disasters as well as forecasting governments’ financial exposure to future shocks. Furthermore, how disaster costs are shared among different levels of government is another important question concerning the intergovernmental dynamics of disaster management.
In the U.S. federal system, the direct fiscal costs of natural disasters (i.e., increased government expenditures due to disaster shocks) are largely borne by the federal government. It is estimated that Hurricane Katrina cost the federal government approximately $120 billion while Hurricane Sandy cost $60 billion. Even in the years without large-scale disaster events, federal disaster spending is between $2 billion and $6 billion annually. Under the Stafford Act, the federal government plays a critical role in funding disaster-related programs (e.g., direct relief, mitigation grants, and subsidized insurance programs) and redistributing the actual costs of natural hazards, meaning that a considerable portion of the local disaster burden is shifted to all U.S. taxpayers. This raises a set of issues concerning the equity and efficiency of the U.S. disaster policy framework.
Managing disasters involves multiphased activities to mitigate, prepare for, respond to, and recover from disaster shocks. There is a common belief that the federal government inappropriately spends far more on ex post disaster response, relief, and recovery than what it spends on ex ante mitigation and preparedness, often driven by political motivations (e.g., meeting voters’ preferences for postdisaster aid) and the current budget rules. As pointed out by many others, federal disaster relief and assistance distort the subnational incentive to invest in local disaster prevention and mitigation efforts. Furthermore, given the mounting evidence on the cost-effectiveness of disaster mitigation programs in reducing future disaster damages, the current practice of focusing resources on postdisaster assistance means substantial public welfare losses. In recent years there has been a call for the federal government to shift its disaster policy emphasis toward mitigation and preparedness and also to facilitate local efforts on mitigation. To achieve the goal requires a comprehensive reform in government budgeting for emergency management.
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.
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.
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?
Dennis John Parker
Humankind is becoming increasingly dependent on timely flood warnings. Dependence is being driven by an increasing frequency and intensity of heavy rainfall events, a growing number of disruptive and damaging floods, and rising sea levels associated with climate change. At the same time, the population living in flood-risk areas and the value of urban and rural assets exposed to floods are growing rapidly. Flood warnings are an important means of adapting to growing flood risk and learning to live with it by avoiding damage, loss of life, and injury. Such warnings are increasingly being employed in combination with other flood-risk management measures, including large-scale mobile flood barriers and property-level protection measures.
Given that lives may well depend on effective flood warnings and appropriate warning responses, it is crucial that the warnings perform satisfactorily, particularly by being accurate, reliable, and timely. A sufficiently long warning lead time to allow precautions to be taken and property and people to be moved out of harm’s way is particularly important. However, flood warnings are heavily dependent on the other components of flood forecasting, warning, and response systems of which they are a central part. These other components—flood detection, flood forecasting, warning communication, and warning response—form a system that is characterized as a chain, each link of which depends on the other links for effective outcomes. Inherent weaknesses exist in chainlike processes and are often the basis of warning underperformance when it occurs.
A number of key issues confront those seeking to create and successfully operate flood warning systems, including (1) translating technical flood forecasts into warnings that are readily understandable by the public; (2) taking legal responsibility for warnings and their dissemination; (3) raising flood-risk awareness; (4) designing effective flood warning messages; (5) knowing how best and when to communicate warnings; and (6) addressing uncertainties surrounding flood warnings.
Flood warning science brings together a large body of research findings from a particularly wide range of disciplines ranging from hydrometeorological science to social psychology. In recent decades, major advances have been made in forecasting fluvial and coastal floods. Accurately forecasting pluvial events that cause surface-water floods is at the research frontier, with significant progress being made. Over the same time period, impressive advances in a variety of rapid, personalized communication means has transformed the process of flood warning dissemination. Much is now known about the factors that constrain and aid appropriate flood warning responses both at the individual and at organized, flood emergency response levels, and a range of innovations are being applied to improve response effectiveness. Although the uniqueness of each flood and the inherent unpredictability involved in flood events means that sometimes flood warnings may not perform as expected, flood warning science is helping to minimize these occurrences.
Scholars agree that the impact of a disaster in a globalized world increasingly extends beyond political and geographical boundaries, creating transboundary disaster events. Though not all disasters fit the description of a transboundary event, many embody transboundary characteristics. For instance, national and transnational financing and other resources directed toward post-disaster humanitarian relief and long-term reconstruction efforts can also create transboundary flows that cross political and geographical lines. Rebuilding after physical damage and economic losses during a disaster, the impacts of which are disproportionately higher in the poorest countries, is a costly endeavor that requires multiple sources of finance. Depending on the scale and visibility of the disaster and local capacities, financial arrangements, resources, and assistance can come from a variety of sources including the government, international institutions, and private-sector, and nongovernmental, and civil society organizations. In particular, transnational financing from bilateral donors and international financial institutions, which constitute multilateral and bilateral streams of financing for post-disaster recovery, comprise a significant percentage of recovery funding globally. Such flows, although inherently transboundary, are not well understood as a phenomenon within the transboundary disasters literature.
Three major types of agencies provide funding for post-disaster reconstruction including multilateral development banks (MDBs), also referred to as international financial institutions (IFIs); bilateral development agencies within donor countries; and United Nations (UN) development agencies. MDBs such as the World Bank are created by a group of countries that utilizes pooled contributions from national governments and additional resources, such as interest collected from loans, to finance development projects. Bilateral development agencies such as the United States Agency for International Development are institutions established by individual countries to provide development funding to nation-states; they work closely with IFIs.
Numerous questions about transnational financing for post-disaster recovery as an important component of the transboundary disaster literature remain unanswered and need further insights. What are the links among transnational stakeholders (i.e., MDBs, bilateral donors, UN agencies, and international nongovernmental organizations) and transboundary financial arrangements for post-disaster recovery? What are the aggregate impacts of transboundary financing on post-disaster reconstruction? How do transboundary financing flows occur among bilateral donors, MDBs, and local and international nongovernmental organizations? Where can scholars find data sets on post-disaster transnational financing? How does transboundary financing impact post-disaster recovery governance in recipient countries? The current state of knowledge on transboundary financing of post-disaster recovery provides some guidance on best practices and the challenges with coordinating and monitoring.
Glacier retreat is considered to be one of the most obvious manifestations of recent and ongoing climate change in the majority of glacierized alpine and high-latitude regions throughout the world. Glacier retreat itself is both directly and indirectly connected to the various interrelated geomorphological/hydrological processes and changes in hydrological regimes. Various types of slope movements and the formation and evolution of lakes are observed in recently deglaciated areas. These are most commonly glacial lakes (ice-dammed, bedrock-dammed, or moraine-dammed lakes).
“Glacial lake outburst flood” (GLOF) is a phrase used to describe a sudden release of a significant amount of water retained in a glacial lake, irrespective of the cause. GLOFs are characterized by extreme peak discharges, often several times in excess of the maximum discharges of hydrometeorologically induced floods, with an exceptional erosion/transport potential; therefore, they can turn into flow-type movements (e.g., GLOF-induced debris flows). Some of the Late Pleistocene lake outburst floods are ranked among the largest reconstructed floods, with peak discharges of up to 107 m3/s and significant continental-scale geomorphic impacts. They are also considered capable of influencing global climate by releasing extremely high amounts of cold freshwater into the ocean. Lake outburst floods associated with recent (i.e., post-Little Ice Age) glacier retreat have become a widely studied topic from the perspective of the hazards and risks they pose to human society, and the possibility that they are driven by anthropogenic climate change.
Despite apparent regional differences in triggers (causes) and subsequent mechanisms of lake outburst floods, rapid slope movement into lakes, producing displacement waves leading to dam overtopping and eventually dam failure, is documented most frequently, being directly (ice avalanche) and indirectly (slope movement in recently deglaciated areas) related to glacial activity and glacier retreat. Glacier retreat and the occurrence of GLOFs are, therefore, closely tied, because glacier retreat is connected to: (a) the formation of new, and the evolution of existing, lakes; and (b) triggers of lake outburst floods (slope movements).