Against wind, plants beat walls
Sally Swartz, Palm Beach Post 23 Apr 08;
The "plants-trump-rocks" solution isn't one governments want to hear
To some in the engineering Establishment, Jim Egan's message might be considered radical, a threat to the status quo. But in his Saturday audience, members of the Martin and St. Lucie Conservation Alliances, the Marine Resources Council executive director had a sympathetic crowd.
He spoke to both groups as part of their annual awards luncheon at a Hutchinson Island restaurant, and what he had to say will resonate with anyone who lives on the Atlantic coast. Engineering solutions - seawalls, bulkheads, blocks, rocks and rubble - don't protect shorelines from erosion, said Mr. Egan, whose council promotes environmental education and shoreline habitat restoration along the Indian River Lagoon, the Treasure Coast section of the Intracoastal Waterway.
What does work? Native shoreline plants, such as mangroves. "As flimsy as plants may look when you put them up against armoring," Mr. Egan said, "plants work better."
Mr. Egan studied the effects tsunamis had on shorelines in Indonesia. "I saw cities saved by mangrove swamps," he said. After the 2004 hurricanes, he also saw the effects storms had on seawalls and other engineered shore armoring systems in communities bordering the lagoon.
After the storms, Indian River Drive washed out along the lagoon's north shore in both Martin and St. Lucie counties. Government's response was $30 million in engineering work along more than 13''miles of riverfront. A year later, when Hurricane Wilma was headed our way, those repairs already had problems. Cable-linked concrete blocks that covered the banks had begun to break and crumble, exposing the heavy, black plastic cloth beneath. Metal parts on the cables had rusted.
Kevin Stinnette, who heads the Indian Riverkeeper group, sought a federal injunction to stop the repairs. A judge denied it. But Mr. Stinnette also asked Mr. Egan for advice about shoring up the riverbank in front of his home. Using mangroves near the water's edge and native grasses, railroad vine, sea oats, buttonwood and palmettos on higher ground, he planted a natural shoreline that withstood Wilma.
Last year, Mr. Egan's testimony about the destructive nature of seawalls, based on his research and track record in a decade with the Melbourne-based council, helped Martin environmentalists block a developer's plan to build a seawall along the Indian River Lagoon near the Jensen Beach causeway. Since 1992, Mr. Egan's council has worked with schools, volunteers and environmental groups to remove nonnative Brazilian pepper trees from a 30-mile stretch of lagoon shoreline and plant mangrove saplings along the river. Schools help collect seeds, grow the saplings and plant them.
The "plants-trump-rocks" solution isn't one governments want to hear, Mr. Egan said. After the first of the 2004 storms, Frances, destroyed an engineered shoreline project near a council building, officials wanted to rebuild with more of the same. "When a rock armor system fails, what do they do?" Mr. Egan asked. "They get more rocks." He has identified three types of shorelines at high risk for "catastrophic" failure: Those with few native plants, those with invasive nonnatives, such as Australian pines or Brazilian peppers, and those that have been "fixed before by engineers."
Mr. Egan, however, has hope. "As the current systems fail, as they inevitably will, we have the research to show what works." How about a truce between engineers and biologists? "We're now seeing a combination of engineering and biological solutions." But he believes that plants promise "the only long-term success."
He notes that "there's no scientific support for what water management districts do to canals," for example, and said research doesn't show that engineering solutions for shorelines are successful. His research on the effects of tsunamis in Asia convinced him. One city removed its beach dune, he said, "and no longer exists." Another did not, "and it's fine."
The lesson in protecting shorelines, he said, is clear: "No man-made structures will survive a Category 4 hurricane. Mangroves tend to lose their leaves. That costs the taxpayers nothing. The leaves grow back."
