Florida may be a bit smaller after Tropical Storm Isaac passes through. The U.S. Geological Survey warned that 78 percent of the state's west central coast and 23 percent of the Panhandle are in danger of having portions of their beaches and dunes swept away.
"With Issac bearing down on Florida beaches so soon on the heels of Debby, this is like a 'one-two punch' for the dunes that provide coastal protection," said USGS Director Marcia McNutt in a press release.
In late June, Tropical Storm Debbie weakened the sand fringing the coast of Florida. Sand dunes and beaches help protect coastal communities and ecosystems from storm surges, but repeated impact from strong storms weaken the defenses.
"Tropical Storm Debby eroded many beaches along Florida's west central coast, impacting the property of many gulf-side residents and hotels," Hilary Stockdon, USGS oceanographer and lead of the assessment team, said in a press release. "Beaches typically take years to recover from severe storm impact, so having what is likely to be a Category 1 or 2 hurricane move up the coast just two months later could take a heavy toll on some already heavily eroded areas."
The raging seas churned up by an intense storm can damage dunes and beaches in three different ways, according to the U.S. Geological Survey's website.
Collision: Waves eat away at the base of dunes when they collide with them. This tends to erode the dunes and reduce their size.
Overwash: Waves and storm surges can go right over the tops of dunes and transport the sand further inland.
Inundation: The most destructive of the three, inundation occurs when beaches are completely submerged by high seas.
"As these sand dunes dynamically morph to new configurations, our science-based models can help in forecasting where communities are at most risk from storm damage in this ever-changing spatial and temporal pattern of storm intensity and coastal morphology," said McNutt.
Probabilities of collision, overwash, and inundation for Isaac. Based on NHC forecast advisory 22, beach and dune erosion is very likely. (USGS)