Saturday, July 06, 2013 12:50 pm
Galveston uses pesky seaweed to fight storm surge
By RAMIT PLUSHNICK-MASTIAssociated Press
But after years of having midnight workers try to clear the beaches of tons of seaweed delivered by the currents, the Galveston Island Park Board of Trustees and Texas A&M University are launching a pilot program aimed at using the sticky muck to build a buttress against severe weather. The pilot program will test a theory that sand dunes fortified by compressed seaweed will be more resilient to storm surges and high tides, protecting the fragile community that has been pounded by countless hurricanes.
The $140,000 project is just one of several ongoing programs along the Texas Gulf Coast designed to use natural resources and the existing habitat to fight rising sea levels and future hurricanes, ideas that have become more popular since 2008, when Hurricane Ike breached Galveston's man-made, multimillion dollar seawall, flooding the inner city and causing more than $20 billion in damage.
"People's mentality about sustainability is increasing. Awareness about the role that each component of nature has in the life cycle is growing," said Kelly de Schaun, the board's executive director. "There now seems to be a political will and disposition to embrace these types of ideas."
Jens Figlus, an expert on coastal engineering with the department of maritime engineering at Texas A&M University at Galveston, said the first challenge is to modify a hay baler - a piece of machinery with small metal teeth used by farmers to collect hay into large round packages - so it can lift heavier, wetter seaweed. The seaweed will be dried and compressed, and covered with sand and plants.
The hypothesis is that similar to large, plant-covered sand piles, a dune that has a strong base of seaweed also will better withstand the force of ocean waves and massive storm surges, he said. As the project continues, researchers will evaluate the seaweed-bound dunes and compare them to others without the same inner foundation.
Figlus believes the nutrients from the seaweed will help plants grow on the dunes, creating a strong storm barrier system. The more energy a storm expends to destroy dunes, the less it has to attack key city infrastructure, he noted.
"If you have to rely on a concrete wall as your defense, you're in trouble," Figlus said of Galveston's seawall, built after a 1900 hurricane that remains the deadliest storm in U.S. history. "The concrete infrastructure should be the last line of defense, not the first."
Capt. Robert Webster, a research assistant at Texas A&M University in Galveston, has spent the past two years tracking the seaweed using NASA satellite imagery in a program called SEAS, or Sargassum Early Advisory System. Every eight days, he receives an image of where the brown algae is, and is able to predict days in advance when there will be a large landing in Galveston. As part of the project, he also has started researching historical landings, to better understand the problem and why it is unique to the Gulf.
The seaweed develops in the Caribbean and takes about three to four months to arrive in the Gulf via natural currents and winds, he said. A great deal of it does not survive in the vast, largely nutrient-free blue waters of the Atlantic. When it arrives in the Gulf, though, the nutrient-rich green water - which in recent years has even greater amounts of nutrients due to agricultural waste flowing from rivers and streams in the Midwest - the algae grows rapidly. It appears to also like the Gulf's warmth.
As a result, Webster has discovered that Galveston and other towns along the Texas Gulf Coast always have had large piles of seaweed. Even after it is collected at night, by morning often there already is another line along the water.
De Schaun said officials struggle with making the coast pleasant for visitors, while leaving some seaweed which also serves to keep a beach healthy.
"It's a challenge," she said.
Galveston's East Beach, the site of the pilot project and one of the island's largest public beaches, already has several 6-foot-high piles of Sargassum dotting the white sand, the efforts of a midnight crew that uses a conveyor-like rake to lift the seaweed and shake out the sand before dumping it into large mounds.
By next season, instead of these large mounds, the park board hopes to have compressed seaweed bales topped with sand between the beach and the parking lot, the beginning of a future line of Sargassum-fortified dunes.
"People have wondered what to do with Sargassum for some time. Now we're trying to incorporate a local issue, namely the seaweed ... and come up with a way to have these dunes grow over time and get rid of the seaweed at the same time," Figlus said. "It's not something that will happen overnight. It will take years."
Plushnick-Masti can be followed on Twitter at https://twitter.com/RamitMastiAP