Over the next five years, Miami Beach plans to spend as much as $500 million to install 80 pumps, raise roads, and build seawalls across the city. In other coastal cities like Aventura, this year’s budget includes $1.6 million for drainage improvements. Countywide, the 2016 budget includes some $300,000 for sea level rise resilience.
But long before there were massive pumps, before it was technically feasible to raise the roads, we had mangroves, dunes, and coral reefs – cheap, natural tools for enduring environmental stress. Now several environmental groups are trying to revive them as an integral parts of climate change resilience plans, particularly for flooding.
It’s about “finding the right balance between green and grey,” said Elizabeth Wheaton, the Miami Beach environment and sustainability director, at the Sea Level Rise Solutions Greater Miami Chamber of Commerce meeting Friday.
On Miami Beach, the values of coral reefs and sand dunes can’t be understated.
Coral reefs are first line of defense against storm surge because they help dissipate a wave’s energy — so that as a wave gets closer to shore, it get smaller and doesn’t end up flooding the streets. Rough reefs close to the water’s surface are the most effective at this, according to a study in Nature. This is because the rougher the reef, the better it is at cutting through the wave and absorbing its energy. And much like a man-made wall, the higher it is, the more of the wave it can stop.
Meanwhile, sand dunes can protect against winds and high waves. We’ve been investing in them for awhile: in the mid-1970s the United States Army Corps of Engineers and the Florida Department of Environmental Protection built up the dunes on Miami Beach, providing storm surge protection and natural habitat for migratory birds.
Since then they’ve continued to grow, adding upwards of 10 to 12 feet as new sand gathers, providing additional protection along the eastern seaboard, Wheaton said.
“Natural infrastructure can provide that natural protection,” she said.
Perhaps the biggest selling point of these natural solutions are the way that they build themselves up naturally. It’s not just the sand dunes. Mangroves react to sea level rise by moving closer into shore or growing higher, said Chris Bergh, The Nature Conservancy’s South Florida Conservation Director.
“Walls are static, so you’re going to build it until it needs to be replaced or repaired. Mangroves are self perpetuating and they can adapt to changing conditions,” he said.
The Nature Conservancy, a charitable environmental organization, is working at more than 40 sites around the world to demonstrate how they can harness natural resources to help combat sea level rise.
The Conservancy has selected two spots in Miami-Dade to test it out: the Miami-Dade County Water and Sewer Department’s South District Wastewater Treatment Plant, located in South Dade, and Wagner Creek, a tributary of the Miami River that runs through Miami’s Health District.
The wastewater plant sits among wetlands neighboring Biscayne Bay, separated by a swath of mangroves and coastal marshes. The Conservancy is analyzing the natural sea wall made up of mangroves and marsh as a particularly valuable resource for protection against flooding of the wastewater treatment plant.
At Wagner Creek, where waters are frequently polluted and flooded by stormwater runoff, the organization is hoping to use nature hacks to both combat flooding and improve water quality of the creek.
To do this, the Nature Conservancy will partner with Miami-Dade County and the City of Miami, and likely plant trees and add shrubbery along the sides of the creek. The goal is to create a natural barrier and water filtration system so that the polluted runoff water is absorbed by neighboring greenery rather than running directly into the creek, according to Greg Guannel, the Conservancy’s Urban Conservation Director.
“We won’t be able to alleviate all flooding, but the idea is to reduce some of it by using natural space,” Gunnel clarified. And while sea level rise and high tides will indeed require a multifaceted approach, as Wheaton summarized, “we need to be looking at how natural systems can be a part of that.”
Roshan Nebhrajani and Ariel Zirulnick contributed to this story.