1. The nature of the hazard
2. The nature of the study area
3. The participants in the drama
Rapid Onset vs. Slow Onset
The speed of onset of a hazard is an important variable since it conditions warning time. At one extreme earthquakes, landslides, and flash floods give virtually no warning. Less extreme are tsunamis, which typically have warning periods of minutes or hours, and hurricanes and floods, where the likelihood of occurrence is known for several hours or days in advance. Volcanoes can erupt suddenly and surprisingly, but usually give indications of an eruption weeks or months in advance. (Colombia's Volcán Ruiz gave warnings for more than a year before its destructive eruption in 1985.) Other hazards such as drought, desertification, and subsidence act slowly over a period of months or years. Hazards such as erosion/sedimentation have varying lead times: damage may occur suddenly as the result of a storm or may develop over many years.
Controllable Events vs. Immutable Events
For some types of hazards the actual dimensions of the occurrence may be altered if appropriate measures are taken. For others, no known technology can effectively alter the occurrence itself. For example, channelizing a stream bed can reduce the areal extent of inundations, but nothing will moderate the ground shaking produced by an earthquake.
Frequency vs. Severity
Where flooding occurs every year or every few years, the hazard becomes part of the landscape, and projects are sited and designed with this constraint in mind. Conversely, in an area where a tsunami may strike any time in the next 50 or 100 years, it is difficult to stimulate interest in vulnerability reduction measures even though the damage may be catastrophic. With so long a time horizon, investment in capital intensive measures may not be economically viable. Rare or low-probability events of great severity are the most difficult to mitigate, and vulnerability reduction may demand risk-aversion measures beyond those justified by economic analysis.
Mitigation Measures to Withstand Impact vs. Mitigation Measures to Avoid Impact
Earthquake-resistant construction and floodproofing of buildings are examples of measures that can increase the capacity of facilities to withstand the impact of a natural hazard. Measures such as zoning ordinances, insurance, and tax incentives, which direct uses away from hazard-prone areas, lead to impact avoidance.
The high density of population and expensive infrastructure of cities makes them more susceptible to the impacts of natural events. Mitigation measures are both more critically needed and more amenable to economic justification than in less-developed areas. Urban areas are likely to have or are able to establish the institutional arrangements necessary for hazard management.
For small towns and villages non-structural mitigation measures may be the only affordable alternative. Such settlements rely on the government to only a limited extent for warning of an impending hazard or assistance in dealing with it. Thus organizing the local community to cope with hazards is a special aspect of hazard management.
The physical characteristics of the land, land-use patterns, susceptibility to particular hazards, income level, and cultural characteristics similarly condition the options of an area in dealing with natural hazards.
Among the "actors" involved in the process of hazard management are planning agencies, line ministries, emergency preparedness and response centers, the scientific and engineering community, local communities, technical assistance agencies, development finance agencies, and non-governmental organizations, not to mention the equally diverse list of private-sector players. Each has its own interests and approach. These varied and sometimes conflicting viewpoints can add to the constraints of planning and putting into operation a hazard management program, but having advance knowledge of the difficulties each may present can help the practitioner deal with them.
Planning agencies are often unfamiliar with natural hazard information, or how to use it in development planning.
Line ministries similarly have little familiarity with natural hazard information or with the techniques of adapting it for use in planning. Projects for the development of road, energy, telecommunications, irrigation systems, etc. often lack hazard mitigation consideration. Furthermore, ministries tend to have little experience in collaborating with each other to identify the interrelationships between projects or to define common information requirements so that information that suits the needs of many users can be collected cooperatively.
The emergency preparedness community has tended to view its role exclusively as preparing for and reacting to emergencies and has therefore neglected linking preparedness to long-term mitigation issues. Furthermore, emergency centers have paid insufficient attention to the vulnerability of their own infrastructure. When these lifeline facilities are wiped out, disaster victims have nowhere to turn. Emergency preparedness policies are beginning to change. For example, international emergency relief organizations such as the International League of Red Cross and the Red Crescent Societies have stated that they will devote more effort in developing countries to prevention.
The scientific and engineering community often sets its agenda for research and monitoring on the basis of its own scientific interests without giving due consideration to the needs of vulnerability reduction or emergency preparedness. For example, a volcano may be selected for monitoring because of its scientific research value rather than its proximity to population centers. Valuable information on hazards is often published in scientific journals in abstruse language. The scientific community should ensure that data are translated into a form suitable for use by hazard management practitioners.
Local communities are jarringly aware of the impact of natural hazards. But they usually have little opportunity to participate in the preparation of large infrastructure and production projects that impinge on them, and even less in setting agendas for natural hazard assessment and vulnerability reduction.
Technical cooperation agencies do not normally include natural hazard assessment and vulnerability reduction activities as a standard part of their project preparation process. "Hazard impact statements" that, like environmental impact statements, are conducted after the project is formulated are not adequate. Hazard considerations must be introduced earlier in the process so that projects are prepared with these constraints in mind.
Development financing agencies engage actively in post-disaster reconstruction measures, yet do not insist on hazard assessment, mitigation, and vulnerability reduction measures in their ordinary (non-disaster-related) development loans, and are reluctant to incorporate such considerations into project evaluation.
Other institutional considerations: Knowledge of and experience with hazard management techniques are rare commodities in most agencies in Latin America and the Caribbean. Thus, if a technical cooperation agency proposes to incorporate these ideas into planning and project formulation, it invariably has to overcome the skepticism of the relevant local personnel. This adds to the cost of formulating a project, but the extra cost can pay high dividends.
Greater consideration should be given to the private sector, as is pointed out by Andrew Natsios in "Disaster Mitigation and Economic Incentives."1/ Natsios, following George Schultze, claims that policy-makers can change social behavior more effectively by changing the incentives of the marketplace, i.e., the public use of private interest, than by regulation. For example, casualty insurance companies could offer a large premium differential for earthquake- and hurricane-resistant construction. He suggests that governments should specify the desired outcome of policy, but leave the method of achieving that outcome to the economic actors.
1/ Natsios, Andrew S. "Disaster Mitigation and Economic Incentives" in Colloquium on the Environment and Natural Disaster Management (Washington, D.C.: The World Bank, June 27-28, 1990).
At the national level, giving a single entity total responsibility for hazard management tends to cause other agencies to see it as an adversary. Instead, each agency that formulates projects as part of its standard activities should appreciate the importance of introducing hazard considerations into the process of project formulation. Planning agencies should take an advocacy position on hazard management and on introducing non-structural mitigation strategies early in the planning process. Such agencies should have personnel trained for these functions.
Similarly, at the project level responsibility for mitigating the impact of natural hazards does not lie with a single individual or component but is an overall responsibility of the project, requiring the cooperation of all components.
Post-disaster reconstruction activities often lack support for hazard assessments intended to ensure that the impact of the next event is less destructive. The problem lies with both the lender and the recipient: the stricken country rarely includes this item in its request, but when it does, the lending agencies often reject it. Reconstruction projects, especially when they are very large, are often managed by newly created implementation agencies. This results in a drain of the already limited supply of technical personnel from the existing agencies and complicates coordination between long-term development and short-term rehabilitation.