Jacksonville Confronts Its Flood Risk

Jacksonville Confronts Its Flood Risk

Stunned by unexpected, historic flooding that swamped Jacksonville three years ago, the northeast Florida city is taking steps to address its flood risk through both a new Special Committee on Resilience and the planned hiring of the city’s first-ever chief resilience officer.

The committee, set up by the Republican-controlled city council, hopes to come up with an initial assessment and blueprint for action in the next few months, according to its chair, City Councilmember Randy DeFoor. The city has budgeted for a chief resilience officer, but the hiring hasn’t happened yet, she added.

Parts of Jacksonville are along the Atlantic Ocean, where erosion and storm surge are problems. But its downtown commercial core and some of its oldest neighborhoods straddle the St. Johns River, 25 miles from where it empties into the Atlantic – close enough to be subject to tides and rising seas. Some of the city’s aging stormwater drainage systems have become overmatched during high tide.  

“We're seeing the river come up through the drainpipes and pour out onto the streets,” DeFoor told Flood Trends

Between the ocean and river, Jacksonville has 1,100 miles of waterfront. To install seawalls along the entire waterfront would cost $3.5 billion – more than any other U.S. coastal city, according to a report by The New York Times

“It’s extremely expensive for the hardening,” DeFoor said. “We need to be thinking about a living shoreline,” which she described as cultivating vegetation along the shoreline and riverfront that would soak up water. “They’re using it in some newer neighborhoods and we’re seeing they work.”

But that won’t solve the most common problem – street flooding caused by heavy rain and tides that push river water back through the drainpipes onto the streets.  

DeFoor concedes that the city is just at the beginning of what will likely be a long, uncertain journey. The next step will be a search for state and federal money to help pay for the projects. 

She anticipates the process will look something like what is taking place in Miami, where the U.S. Army Corps of Engineers is proposing a $4.6 billion plan to protect the city from coastal surges during a hurricane. The federal government is helping pay for it.

But Miami’s plan is designed to protect the city from a hurricane surge, not the kind of “sunny day” flooding that afflicts both Miami and Jacksonville. The plan does nothing for street flooding caused by heavy rain or tides that overwhelm stormwater drains. 

In fact, Jacksonville is likely to need something entirely different from what the Army Corps has planned in Miami, where a destructive hurricane surge is seen as the most immediate and gravest threat.

Indeed, Jacksonville has 22 miles of ocean beaches. So, coastal erosion, surge protection and beach replenishment have been concerns over the years. But they weren’t the impetus for Jacksonville’s flood resiliency initiative. It was prompted by widespread flooding caused by Hurricane Irma in 2017 – flooding that took city officials and residents by surprise and revealed the city to have a unique, completely unforeseen vulnerability.

The flooding in 2017 was caused by St. Johns River water flowing toward Jacksonville from two directions at the same time – downstream from the river’s 8,840-square-mile drainage basin and upriver from the sea. 

The two great flows met head-on in Jacksonville, causing the flooding.

The water coming downriver was caused by Hurricane Irma, which had traveled up the west side of the peninsula. It dropped heavy rainfall throughout the St. Johns basin, the runoff gathering and draining downstream toward Jacksonville, and the ocean beyond.

It never drained into the sea because it was blocked by seawater coming in the other direction. 

The flow coming toward Jacksonville from the ocean was caused by a nor’easter that had parked itself in the nearby Atlantic. For days, its winds pushed seawater up the river toward the city. As Irma passed, the upriver push from the sea was augmented by an untimely tidal surge related to the lunar calendar, not the nor’easter.

When the downstream flow and the upstream surge collided in the Jacksonville area, the excess water had no place to go except by overtopping the river banks and flooding the city, which it did.

“Irma really was a wake-up call for us," DeFoor said. 

Now, comes the hard part – fixing it.