This is the overarching theme for Dr Robert Wasson’s research.
Environmental disasters result from a combination of hazards (e.g. floods, tsunamis, earthquakes, landslides, cyclones, geomagnetic storms) and human vulnerability (e.g. location of human settlements, preparedness for hazards including warning systems, human health, gender). The descriptor ‘natural disasters’ is still used (see the figure below from the Centre for Research on the Epidemiology of Disasters, CRED) even though all environmental disasters have both an environmental component, which is increasingly human-induced (e.g. extreme rainfall as a result of global warming), and a human component. Environmental disasters are globally the most damaging in Asia, with more deaths and people affected but about the same amount of economic damage as in the USA between 2001 and 2010 (CRED), and the total number of reported environmental disasters increased faster than elsewhere until 2000 when worldwide the number appears to have plateaued or slightly declined. The same source shows that between 1990 and 2012, floods in Asia caused damage of USD330 billion (30% of total environmental disaster damage in Asia) compared with USD520 billion (49%) from earthquakes.
In many Western countries, disaster management agencies attempt to identify potential hazards as a basis for preventative policy and action; in Asia the emphasis is mostly focused on response to disasters rather than prevention. The Sendai Framework for Disaster Risk Reduction (SFDRR), which in 2015 replaced the Hyogo Framework for Action (HFA) (2005-2015), stresses that prevention is better and more cost-effective than response alone, although response will always be required as prevention rarely provides sufficient protection against the largest disasters. The SFDRR also gives much more emphasis to knowledge as an indispensible component of Disaster Risk Reduction (DRR).
Given the environmental and human components of disasters it is essential that a cross-disciplinary approach be adopted to produce the knowledge for DRR. Prevention or response designed by only considering vulnerability may fail if hazards are poorly identified or increasing. Equally, DRR designed by only considering hazards is likely to be a waste of resources. In addition, including only one hazard in an analysis can miss the key feature of many disasters, namely that they often involve more than one hazard and often cascade: one disaster triggers others with consequences far into the future. For example, earthquakes can damage nearby settlements and their populations by ground motion but also can trigger landslides that block rivers, producing lakes that burst and flood areas downstream, damaging settlements, human health and components of the economy distant from the earthquake source.
Adopting a cascading multi-hazard approach to analysis is a forward-looking view, yet disasters are often incubated over decades and even centuries as people move to dangerous locations driven by social forces that take no account of possible future disasters. Therefore a backward-looking view is also necessary to understand how vulnerability has evolved. History is also required to determine hazard frequencies, magnitudes, trends and causes. Without both forward-looking and backward-looking views, the knowledge input to DRR is likely to be inadequate and the causes of disasters misunderstood.
This approach can be illustrated in the case of floods in Asia where river floods have about the same economic impact as earthquakes and the damage is apparently increasing (EM-DAT). But it is not clear if the increase is a result of increasing flood hazard frequency and/or magnitude, increasing vulnerability or a combination of these phenomena. Without a better understanding of the causes of the apparent increase of this type of disaster, the design of policy will be severely hampered. In addition, the cascading nature of floods is rarely analyzed.
Even with better knowledge, however, uncertainty will remain. This is particularly the case for the most extreme events, best described as events of high consequence and low probability (HILP). Such events raise questions about both the kind of knowledge that is most useful for policy formulation and the optimal policy response. Policymakers can take a probabilistic approach coupled with a cost-benefit analysis, a worst case approach possibly moderated by identification of the maximum credible event(s), or do nothing. Where the uncertainty of frequency is very high but the hazard is reasonably well known, the best approach may be to build resilience rather than attempt probability-based planning.
- Reconstruction of long records of floods using measured flows, documentary evidence, and geomorphic information such as sedimentary archives to determine causes and trends.
- Reconstruction of histories of vulnerability, particularly identifying the time scales and nature of disaster incubation, to determine causes and trends.
- Building system dynamics models of the interactions of these histories to include cascading disasters and account for non-linear and feedback relationships as a knowledge input to policymaking.
Water Science and Public Policy