An important challenge of natural hazards is that they inflict the greatest total economic damage in large, developed countries, where wealth is aggregated, but they create the greatest economic impact in smaller and developing countries, where a disaster caused by a natural hazard can easily overwhelm a national government’s ability to respond and its economy to recover. Thus, a common understanding in the literature is that the fiscal effect of a natural hazard is a function of the size of the disaster relative to the size of a nation’s economy at the time of the disaster. At the international level, the economic impact of disasters, for example, has been estimated to be US$2.9 trillion between 1998 and 2017, and approximately $945 billion of that occurred in the United States. With a 2019 gross domestic product (GDP) of $21 trillion, the total economic effect for those 20 years is close to 5% of the value of economic output for a single year. Developing country losses, on the other hand, can be overwhelming, especially as measured against the size of the economy. For example, Hurricane Maria’s impact on Dominica is estimated to have been approximately US$1.37 billion, which was equivalent to 225% of Dominica’s GDP. While an appreciation for the connection between the size of a national economy and natural hazards is clearly critical, the literature points to a number of additional factors that are important to understand about how government financial conditions are affected by natural hazards and vice versa. Debates continue about the role of foreign direct investment, government and private debt levels, investments in education, and internationally sponsored protective actions and insurance pools in improving the resilience of smaller and developing countries to disasters. For example, structural approaches to understanding the linkage between disasters and economic development suggest that countries with a limited number of sources of income have economies that are more vulnerable to disasters than more diversified economies, which might suggest that fiscal policies designed to increase economic diversity are important. Neoclassical approaches, on the other hand, argue that economic recovery is slowed by government intervention in the economy, and suggest that the best way for developing economies to recovery quickly is to reduce the amount of regulation in the economy. Whatever the theoretical approach, what remains most clear is the ongoing challenge of decoupling the emotional need to participate in responses to the human tragedy associated with disasters caused by natural hazards from the strategic imperative to invest in hazard mitigation at much higher rates globally and plan toward disaster risk reduction.
Mohammed Alkhurayyif, Julie Winkler, Simon Andrew, and Skip Krueger
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.