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Irma, Ian and Nicole: What impact did recent hurricanes have on St. Johns River?

The Florida Times-Union 12/6/2022 Quinton White

With the recent end of hurricane season, the entire Gulf of Mexico and southeastern coast of the U.S. can breathe a giant sigh of relief.

What a year for hurricanes, but not the year we expected. The predictions had been for more frequent and severe storms. Thankfully they did not materialize in the numbers, but what we got was pretty bad.

Massive flooding, enormous amounts of shoreline erosion and extensive structural damage on both sides of Florida. It is small consolation that it could have been worse. When you are in the path of destruction, all it takes is one.

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From a scientific and hydrological perspective, the way hurricanes impact the St. Johns River is extremely interesting. As everyone knows, Florida is very flat and the St. Johns River is too. So when hurricanes impact Florida and the river, each takes on its own set of unique characteristics.

Comparing and contrasting three of our recent hurricanes illustrates that fact. Irma, Ian and Nicole were all different in how they affected the St. Johns River. Some of that had to do with their timing, where they made landfall, along with their general size and intensity as they moved along the river.

You also need to couple those factors with all the filled wetlands, paved roads and parking lots that have altered the river’s ecosystem over the last 200-plus years. Not to mention the thousands of acres of forest that have been removed.

Irma was a gigantic hurricane that came ashore in Southwest Florida, then moved up the western side of the state. At one time, the storm effectively covered the entire peninsular of Florida raining trillions of gallons of water on the state and into the St. Johns River basin. That water flowed slowly north until it reached Jacksonville.

At that point, timing comes into play with the tidal surge pushing into the river as water was trying to flow out. The two opposing forces combine to produce massive flooding in Riverside and downtown Jacksonville.

Then there was Ian which also made landfall in Southwest Florida, but with Category 4 winds and flooding that effectively destroyed Sanibel and Captive Islands. Ian then moved across the state before going back into the Atlantic near Cape Canaveral.

Hurricane Ian again deposits a great deal of rain but nowhere near as much as Irma. And despite passing off Jacksonville during a high tide, did far less damage than Irma.

Compare that to what happened with Hurricane Nicole which made landfall near Vero Beach and crossed the state going more east to northwest. Nicole was more noteworthy because of the tremendous amount of shoreline erosion and beachfront homes destroyed or damaged. We effectively lost millions of cubic yards of sand. Sand that we taxpayers had just paid to have deposited.

But Nicole was not alone in attacking our beaches. She was preceded by three days of Nor’easter winds and wave action. So the beaches received sort of a one-two punch.

So we have three hurricanes, all similar in some ways and all different in their own way too.

a man wearing glasses posing for the camera: Quinton White, River Life © Bob Mack/Florida Times-Union Quinton White, River Life

Glad you asked River Life

How many dolphins are there in the St. Johns River?

Scientists at Jacksonville University, University of North Florida and the National Oceanographic and Atmospheric Administration believe there are about 300 dolphins that use the St. Johns River on an annual basis.

Roughly half are here year-round and half are seasonal residents. It is difficult to get a precise count. You really only know how many you saw. You do not know how many went undetected. It is possible to identify individual dolphins by their fin pattern, and over time, you can see patterns and trends, but that takes years of systematic research.

River Life runs the first Tuesday of each month in The Times-Union. Email Quinton White, executive director of Jacksonville University’s Marine Science Research Institute, with questions about our waterways at qwhite@ju.edu. For more on the MSRI, visit ju.edu/msri.

This article originally appeared on Florida Times-Union: Irma, Ian and Nicole: What impact did recent hurricanes have on St. Johns River?

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