Some Florida beaches are growing
University of Florida scientists found that beaches on Florida's east coast are increasing in size at the average rate of about four inches each year
April 29, 1999
Web posted at: 12:20 PM EDT
The news is not all bad.
At a time when beach restoration projects are commonplace, a University of Florida study has found that unlike many beaches on the East Coast, Florida's Atlantic beaches are actually growing in size.
Florida's unique location in relation to Atlantic currents and wave patterns have given the state a special resilience against coastal erosion and steadily rising sea levels.
The study, led by Bob Dean, a UF coastal engineering professor, analyzed available historical and recent shoreline measurement data in Florida's 24 counties with sandy beaches, including 12 on the Gulf Coast and 12 on the Atlantic Coast. Measurement records dating back at least a century were available for all counties.
The scientists used the data to outline changes in Florida's shorelines and found that beaches on Florida's east coast are increasing in size on average at the rate of about four inches each year. Beaches on Florida's west coast are remaining about the same size on average, according to the researchers.
In contrast, beaches in other Atlantic states are shrinking or disappearing on average, some very quickly, Dean said. For example, Virginia's coast retreats as much as 10 feet annually, he said. Only one other Atlantic state -- New York -- is experiencing a similar average net gain in its beach sizes, Dean said.
According to Dean, several factors have led to Florida's situation.
First, currents along the Eastern Seaboard generally travel in a southerly direction, moving sand from north Atlantic states south toward Florida's beaches.
In addition, before the recent period of sea level rise -- a process that started about 20,000 years ago -- the continental shelf off of the East Coast was the repository of sand from the many rivers that empty into the Atlantic. During more recent times, sea level increases at the rate of about 10 to 12 centimeters per century have resulted in waves pushing this sand ashore onto East Coast beaches.
Dean said wave energy is higher in the northern Atlantic states than in Florida, and he speculated those states already had exhausted their offshore sand deposits.
UF researchers, however, warn that although Florida east coast beaches are growing, some are still eroding rapidly, particularly those located near man-made inlets such as St. Lucie Inlet. Inlets lead to erosion partly because jetties and deep channels disrupt the normal southerly flow of sand, and partly because inlets carry sand away from beaches.
"Having an average shoreline that's in good shape doesn't mean the whole shoreline is in good shape," Dean said. "There are a lot of places that are in pretty serious condition in terms of erosion."
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