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South Florida’s climate change solutions

South Florida’s climate change solutions

May 6, 2016 at 12:00am

By Eric Barton

There’s no doubt among scientists that the climate is changing and the seas are rising, and so the work being done at FIU these days has moved from proof of the problem to solutions. In South Florida, that means fixing three major environmental issues associated with rising seas.

Fighting the seas with fresh water

Back before the massive development of South Florida, fresh water flowed naturally from the north end of the peninsula, making its way through swamps and estuaries and all the way out to Florida Bay. Water that flowed down the peninsula kept seawater from entering the Everglades, creating a natural estuary of fresh and brackish water.

Dams and levees built in the last century changed that. These days, water gets trapped before heading south, destined to be used as drinking water, to feed farms or flushed through canals into the ocean. Now, salt water has begun to invade. If it continues, the seawater could split Florida into two peninsulas, with a bay in the center, swamping the Everglades. Aside from the devastating loss of a natural resource, salt water would drown aquifers that supply South Florida with drinking water.

scanlon-quote-png-1.pngLuckily, we already know how to fix this, says René M. Price, chairperson of FIU’s Department of Earth & Environment in the College of Arts, Sciences & Education. The answer is comprehensive Everglades restoration that begins with returning to the natural freshwater flow. That means breaking down levees and dams and buying up farms located in former wetlands. “If we work to protect the Everglades, it works to help protect our future,” Price said.

These are plans that began in the late 1990s and are backed by local and federal regulators. But Price said the trick these days has been convincing those in power in Tallahassee to continue with the plans, including expensive buyouts of sugarcane fields.

Among the work Price has done at FIU was producing a paper that predicted when scientists would know precisely how high the seas would rise due to climate change. Currently, computer models are predicting a wide range of futures, from the seas rising a few inches in the next century to several feet, which makes planning difficult. By 2025 or 2030, Price determined, computer models will have the data they need to make an accurate prediction on just how much the seas will rise.

“That gives us 30 years to come up with some possible solutions,” Price said. “And that’s what we’re working on now.”

Protecting wetlands so they can protect us

If you’ve ever been up close to a mangrove swamp, you’ve seen the tentacle-looking roots the plants send into the soil. They create a tangle in and out of the sand, and it works like a screen on a bathtub drain — letting water flow out but keeping soil in place.

And that’s why swamps can provide such protection, says Evelyn Gaiser, an aquatic ecologist and executive director of FIU’s School of Environment, Arts & Society. When a storm hits Florida, the mangroves and grasses and other plants not only keep soil from eroding but they also slow down storm waters that could threaten coastal communities.

Unfortunately, the salt water now threatening the Everglades is killing these mangroves and grasses. If that continues, soil could erode at a far faster rate. If the wetlands erode entirely, and we end up with a bay in the center of the state, a hurricane could cause an unfathomable disaster: a storm surge that could inundate western communities in South Florida and eastern development in Southwest Florida.

“Luckily we have a good solution to this, and that’s restoring the freshwater flow to the Everglades,” Gaiser said.

FIU scientists have taken the lead on championing for the restoration efforts using studies and papers that show the positive effects of the work done so far. They’ve also spoken to regulatory groups and before hearings to show how continued efforts will protect South Florida’s future.

Among the restoration efforts conceived with help from FIU scientists is a series of water retention areas in the Everglades. They will not only provide drinking water but will help divert the flow of water naturally, south toward Florida Bay.

“We need these big, expansive wetlands, and we need a lot more acreage than we currently have,” Gaiser said. “What we currently have does not equal the kind of protection we will need in the future.”

Read more about rising seas: A legacy not yet written

Keeping the floods at bay

To understand South Florida’s potential flooding problems, it’s best to imagine it as a sponge, floating just above the surface of a dish of water. For now, we’re just above the water line, and when a big storm hits, the water can safely seep through our porous soil.

But when the seas rise, things get tricky. Unlike other more rocky coastal areas like New Orleans, it’s not as simple as building levees and holding back the water, explains Ali Mostafavi, assistant professor at FIU’s OHL School of Construction in the College of Engineering & Computing. If climate change puts South Florida below sea level, the water will come up through our sandy soil.

briceno-quote-png-1.pngThere are solutions that FIU scientists are researching, Mostafavi said, but it’s not simple. “There is no one solution where you can say, if we do this we will fix it,” he said.

The main problem with creating a fix is that we still don’t know how high the seas will rise. With a few inches, there are costly changes we can make to stave off big problems; with a few feet, it’s likely nothing can be done to prevent South Florida from becoming a wetland, Mostafavi said.

With a few inches of sea level rise, seawater will threaten to seep into underground aquifers that provide our drinking water. One remedy: add a desalinization process to our water treatment plants. It’s a pricey solution and one that has to be completed before the seas ruin the freshwater supplies. Those underground aquifers can also be protected by injecting fresh water into them, filling them so that seawater has nowhere to go, Mostafavi said.

If the seas rise more than that, it’ll require a more complicated fix that could involve barriers to divert ground water, replacing locks along canals, and building pump stations throughout South Florida to replace the current system that works on gravity. It’s an exorbitantly costly solution that might not even keep the seawater back, so it’s one that likely won’t begin until we know for sure how high the seas will rise, Mostafavi said.

The key is that FIU’s researchers are concentrating on what can be done now. “Panicking over the worst-case scenario or being laid back about the best case is the worst thing that can happen,” Mostafavi said. “We have to concentrate on what can be done.”  

Read about a class where students redesign a coastal park to face rising seas