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.
Assessment and Adaptation to Climate Change-Related Flood Risks
Brenden Jongman, Hessel C. Winsemius, Stuart A. Fraser, Sanne Muis, and Philip J. Ward
Natural Disaster Risk Financing and Transfer in ASEAN Countries
Sommarat Chantarat and Paul A. Raschky
ASEAN countries are frequently hit by a variety of natural disasters, and a large fraction of economic activity in ASEAN countries is located in areas exposed to these natural perils. Increasing disaster damages require ASEA countries to manage the financial losses in a more efficient and proactive manner. Currently, most risk-transfer mechanisms in this region rely on ad-hoc government relief, which is not sustainable. Multilateral cooperation in the areas of risk-modeling and mapping as well as joint efforts to establish financial risk-transfer solutions could help to overcome existing challenges in this area.
Natural Hazards Governance in Western Europe
Florian Roth, Timothy Prior, and Marco Käser
Western Europe is an area dominated by established democratic governments, backed by strong economies, for the most part. Drawing on refined technical risk analyses, preventive measures, and comprehensive resources for emergency response, countries from Western Europe have managed to mitigate the most prevalent and recurring hazards. Over the centuries, European governments have been successful in reducing the death toll related to natural phenomena. This has been achieved by addressing all three dimensions of the risk triangle—hazards, exposure, and vulnerability. However, cultural and political differences result in subtle, but distinct differences in the context of natural hazard governance. While these differences can be considered a strength in dealing with local hazards under specific contexts, they can complicate effective and coordinated prevention, preparedness, and response measures toward large-scale hazards. This is especially the case with transboundary hazards, the regional response to which has strongly influenced hazard governance in Western Europe. Evolving risk circumstances have resulted in constant adaptations in hazard governance in the region, including local, national, and transboundary arrangements, and a more recent re-localization in the face of new complex threats that has fallen under the umbrella of resilience building.
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.
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.
Disasters and Large-Scale Population Dislocations: International and National Responses
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.