CDMP Progress Bulletin

Belize Storm Hazard Assessment

Bulletin Date: December 1999

The General Secretariat of the Organization of American States (OAS), under an agreement with the Office of Foreign Disaster Assistance of the U.S. Agency for International Development, is executing a five year Caribbean Disaster Mitigation Project (CDMP). One component of this project is the assessment of potential hazards generated by tropical storms, in terms of storm surge, coastal flooding and extreme wind.

For this purpose, the OAS/CDMP has developed a computer based numerical model called TAOS that produces estimates of maximum sustained surface wind vectors, and maximum still water surge and wave heights at the coastline, for any coastal area in the Caribbean basin. The model relies on a generic data base structure, using US Geological Survey (USGS) digital data for deep ocean bathymetry, US Defense Mapping Agency (DMA) digital data for land boundaries and rough topography, satellite imagery for foreshore bathymetry and land cover, and the National Hurricane Center data base for storm data. Model runs can be made for any historical storm, or for probable maximum events associated with different return periods. Model outputs can be exported to common GIS formats.

Presentation of Belize Coastal Flood Hazard Study

The TAOS model was used to study the wind and coastal storm surge hazards for Belize at a national level. The study produced; 1) a historical return interval analysis for five coastal locations, 2) a series of wind hazard maps with probable surface winds for the five Saffir/Simpson hurricane categories, and 3) a series of coastal storm surge maps for each of the five categories. The coastal locations were Ambregris Cay, Belize City, Dangriga, Monkey River Town, and Punta Gorda. They were selected to represent the variability of return times along the Belize coast. For each location, statistics for storm tracks were extracted from the U.S. National Hurricane Center's historical storm database, covering the years 1886-1992. Each storm in the database was then processed using the TAOS model to determine its effect on the target location. This resulted in: 1) general statistics such as how many years had multiple storms, how many years had storms etc. and 2) an analysis of the time interval between occurrences of each storm category. According to the model output, a category 4 hurricane on a westbound track with forward speed of 5 m/sec creates a storm surge at coastline of between 5m and 6m, and winds of up to 60m/sec. A half day presentation of the model and the resulting coastal hazard maps was organized on November 30^th, 1995 and was attended by thirty persons representing key government agencies, the engineering community, the insurance industry, and the NGO community. Meetings were also held with several government officials, the Director of the OAS office and the Representative of USAID to discuss various aspects of the project and its applications in Belize.

Installation of TAOS RFS Surge Forecasting Model in Belize

The TAOS Regional Forecasting System was installed in the National Meteorological Office and the National Hydrological Office of Belize. Staff persons from each office were trained. Part of the training consisted in a simulation of a class 3 hurricane impacting Belize City, which enabled the participants to determine among other things how many hours prior to the storm the two roads that lead out of the city would be cut off by flooding, or become impassable due to wind, factors that needs to be taken into account for evacuation planning.