PAHO: New Caribbean Basin wind hazard maps

Introduction*

PAHO/WHO, through Applied Research Associates, has developed new state-of-the-art wind hazard maps for Caribbean islands and nearby coastal areas of Central and South America. The maps use the most up-to-date meteorological records and methods and are intended to replace older maps currently in use for structural design and risk assessment. They are an important aid for engineers, developers, and others whose work requires knowledge of wind hazards.

Why were new wind hazard maps prepared?
1. The present project includes the Caribbean coastlines of South and Central American countries. In several of these cases there is no presently available wind hazard guidance for structural design purposes. The new maps will plug that gap.
2. The only pan-Caribbean wind hazard maps ever produced for application in the design of structures were in 1969 (Caribbean Meteorological Institute – H C Shellard), 1981 (Caribbean Meteorological Institute – B Rocheford), 1985 (University of Western Ontario Boundary Layer Wind Tunnel Laboratory – Davenport, Surry, Georgiou).
3. Since 1985 the region has collected another 23 years of relatively reliable data. The incorporation of these data would serve to improve the quality of currently-available wind hazard information.
4. There have been developments in the science and technology related to the long-term forecasting of hurricane activity in the North Atlantic (including the Caribbean).
5. The past 13 years of higher-than-normal hurricane activity in the North Atlantic has led to the questioning of wind design criteria incorporated in the present standards in the Caribbean.
6. This, in turn, has led to uninformed and unreasonable and counterproductive decisions on appropriate basic (and therefore design) wind speeds for some Caribbean projects and in some Caribbean countries.
7. The phenomenon of hurricane activity in the Caribbean is best dealt with regionally and not in a country-by-country manner.

What use will be made of the results of the proposed project?
1. New regional standards are currently being prepared in a project funded by the Caribbean Development Bank (CDB) and executed by the Caribbean Regional Organisation for Standards and Quality (CROSQ). These will replace the Caribbean Uniform Building Code (CUBiC). The CDB-CROSQ project does not include new wind hazard maps for the target region. These new Caribbean Basin maps have been prepared to be consistent with the CDB-CROSQ intension to base the new standards project on the USA “International” codes which reference the wind load provisions of the American Society of Civil Engineers (ASCE 7 Chapters 2 and 6). Thus the results of this wind hazard mapping project could be plugged directly into the new CDB-CROSQ standards.
2. Those Caribbean countries which, for whatever reason, are developing their own standards and not participating in the CDB-CROSQ project will also require wind hazard information. This wind hazard mapping project will provide wind hazard information which could readily be represented in forms designed to fit directly into standards documents with different approaches. (Technical standards in the Caribbean are best dealt with regionally and not in a country-by-country manner. This comment relates particularly to the Commonwealth Caribbean.)
3. Engineers in all Caribbean countries are designing projects every day which must resist the wind. Confidence in the wind hazard information is important to designers. Clients sometimes wish to specify the levels of safety of their facilities. Insurance providers sometimes wish to know the risks they underwrite. This depends critically on the quality of hazard information. Financing institutions sometimes wish to specify wind design criteria for their projects. There is, in summary, an immediate and palpable need for wind hazard information based on up-to-date meteorological records and methodologies recognised by consensus in the scientific community.

The open process adopted in his project is exemplified by:
1. The present Caribbean Basin Wind Hazard Maps (CBWHM) project has prepared a series of overall, regional, wind-hazard maps using uniform, state-of-the-art approaches covering all of the Caribbean islands and the Caribbean coastal areas of South and Central America. The project was executed in consultation with interest groups throughout the target region.
2. An interim, information meeting was held at PAHO in Barbados on 01 October 2007. Meteorologists, engineers, architects, emergency managers, standards personnel and funding agency personnel from the wider Caribbean were invited (and were funded) to attend.
3. At that meeting the principal researcher, Dr Peter Vickery of Applied Research Associates (ARA) described the methodology for developing the maps; presented the interim results available at the time of the meeting; received comments from participants and answered their questions; discussed what systems need to be put in place to improve knowledge of the wind hazard in the Caribbean region and outlined the further work to finalise the present mapping exercise.

* Prepared by Tony Gibbs

The Pan American Health Organization would like to thank the following agencies and individuals responsible for the preparation of the new maps: Peter Vickery, principal researcher, Applied Research Associates; Tony Gibbs, regional coordinator, CEP International Ltd; and the United States Agency for International Development, funding agency.

Questions about the Wind Hazard Map project should be directed to Dr. Dana van Alphen at vanalphe@paho.org.