These particular coastal surge maps illustrate the locations of some of the major oil refineries in Louisiana and Texas along the Gulf Coast in relation to storm surge zones.
The first map depicts storm surge risk across the Gulf Coast along Texas and Louisiana.
The second map depicts the risk among the massive refinery complexes in
The next map shows storm surge potential for Destrehan, La.
And the fourth map illustrates surge potential for Corpus Christi, Texas.
Extreme risk would be areas inundated by all hurricanes (Category 1-5), while low-risk areas are the farthest inland, have the lowest frequency of occurrence and require a powerful storm to push coastal water a great distance from the coast (e.g., Category 5 hurricanes).
The colors on the map indicate the storm-surge risk-level zones. Red represents areas that have the highest risk (level 5) and would be affected by even a Category 1 hurricane. Green represents the areas with the lowest risk (level 1), which would only be affected by a Category 5 hurricane. Orange represents a risk level of 4, which would be affected by a Cat 2 storm, and so on.
The surge inundation risk zone maps were generated for the worst case scenario for each category of storm, assuming for instance high tide, the hurricane hitting perpendicular to the coast and a property location on the right (on-shore wind) side of the eye.
A hurricane's wind and forward speeds both contribute to its power. The angle at which it strikes the shore is also critical; the more perpendicular the track is to the shore, the greater the surge produced.
The tidal stage also must be considered; the storm surge is essentially added onto the tide height. Finally, near-shore water depth and topography greatly affect the surge height, with shallower water intensifying the surge.
Barriers, both natural and man-made, serve as deterrents to the surge.
Finally, the elevation of a property is crucial in determining its risk of inundation.
SOURCE: First American, whose hazard scientists have developed a comprehensive model that outputs maximum storm surge water elevations using offshore and onshore variables, storm heights derived from past hurricanes and simulations using thousands of hurricane paths.
October 15, 2009
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