Wave Hazard Assessment for Selected Sites on the West Coast of Dominica, West Indies
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Dominica can expect to have intermittent cyclonic storms in the future. They occur seldom enough that people are sometimes lulled into forgetting them, but they are a constant hazard.
The western shore of Dominica is sheltered from the surf produced by the tropical trade winds. This relative shelter is null and void during cyclonic storms since, by definition, they blow from all points of the compass.
The western shore is particularly vulnerable to heavy storms. The shore is open, with no distinct bays. It is steep, with a narrow underwater shelf and talus slopes at the mean low water line. The steepness means that coastal flooding will not penetrate far inland, but steepness has also forced the coastal highway and other important infrastructure into precarious sites right on the shore.
Local construction practices reflect the uneven distribution of risk. They are good enough for ordinary weather, but they are not designed to withstand hurricanes.
The hurricane model presented above has revealed that the vulnerability of the coastal structures varies considerably for 10-year and 25-year events. The most vulnerable locations, as revealed by the model, match with the locations where damage was observed after Hurricane Marilyn in 1995.
For stronger storms, the vulnerability becomes more uniform. The rising waters of the storm surges for 50-year events flood the coastal rocks and reefs, where they occur, by two to three meters. Storm waves on top of this flood reach the coast with more of their full force.
It is possible to reduce the uncertainty of tropical cyclonic storms by using mathematical modeling. The digital models discussed above, and the digital databases with which they work, are tools for planning. They produce data precise enough to aid design engineers, and they produce the data for the whole area simultaneously.