by Patricia W. McDermott, P.E., (M.ASCE), Project Manager; Dewberry & Davis, Fairfax, VA,
Darryl J. Hatheway, Senior Coastal Scientist; Dewberry & Davis, Fairfax, VA,

Serial Information: Civil Engineering—ASCE, 1997, Vol. 67, Issue 3, Pg. 52-54

Document Type: Feature article


When Hurricane Fran slammed into the North Carolina coast last September, it ravaged a fragile barrier island system already torn up by Hurricane Bertha two months before. The result was overtopped islands, flooded inlets and extensive structural damage along a one hundred mile stretch from Caswell Beach to Beaufort. As clean-up efforts began, teams from Dewberry & Davis, Fairfax, Va., raced against them to precisely survey the flood's reach before it was scrubbed away. Knowing how high the water had surged would be crucial to communities that wanted to rebuild, federal agencies that wanted to redraw the flood zone maps and insurance companies facing staggering claims. Surveying was difficult, however, as many surveying landmarks were either destroyed by the storm or buried under debris. With 100 miles of coast to survey and only a few days to survey it, we looked to portable global positioning system (GPS) units for help. Although the unit's initial accuracy of plus or minus 100 meters was insufficient for our needs, we employed a system whereby their accuracy was increased until eventually, we could provide data to maps that were accurate to just a few centimeters. The result is a new understanding of flood risk on the North Carolina coast.

Subject Headings: Floods | Mapping | Islands | Hurricanes, typhoons, and cyclones | Global navigation satellite systems | Wave overtopping | Water level

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