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Posts Tagged ‘Sediment’

BY RACHEL DOVEY

The team led by SCAPE proposes breaching levees to allow trapped sediment out, creating a stronger network of marshes and mudflats that can cushion developed areas. Image courtesy SCAPE/Public Sediment team.

They’re no stranger to wildfires and drought, but the cities around the San Francisco Bay haven’t been hit with a climate change-fueled disaster on par with Hurricanes Sandy or Harvey—yet. Still, sea-level rise won’t spare the metros. Even if they escape the drowning predicted by certain apocalyptic maps, Bay Area residents rely on freeways and rail lines built on soft, low-lying bay fill—areas particularly vulnerable to flooding and erosion. And the region’s tidal marshes and mudflats, which should act as natural barriers, are slowly losing sediment owing to poorly engineered dams.

“Unlike New York City, the Bay Area has all these slower and more invisible problems related to climate change,” says Gena Wirth, ASLA, the design principal at SCAPE Landscape Architecture.

The Resilient by Design Bay Area Challenge is bringing some of those unseen issues to light. Last year, judges selected 10 winning teams (SCAPE is the leader of one) made up of ecologists, designers, and landscape architects to imagine infrastructure that works with the region’s shifting landscape rather than against it. The challenge, which is funded by the Rockefeller Foundation, among others, is modeled on New York’s post-Sandy Rebuild by Design contest, with one key difference: This one is proactive, not reactive. Instead of waiting for federal funds to come in after a disaster, (more…)

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BY ZACH MORTICE

Texas National Guard and Texas Task Force responders conduct aerial search and rescue in Rockport, Holiday Beach, and the Port Aransas area. Image courtesy of Wikimedia Commons, photo by the Texas National Guard.

An unprecedented storm that dumped more than 50 inches of rain onto Texas over just a few days, Harvey was the kind of hurricane that worsening climate change promises to bring back for a sequel. And if and when that happens, the next round of  recovery and resilience calculus might best begin with the results of the National Science Foundation’s series of research grants dedicated to studying the storm’s effects.

Last month, the agency handed out just over $5 million across 59 research projects prompted by Hurricanes Harvey and Irma, including several that deal with the ecological and landscape fallout of catastrophic storms. Each promises to generate valuable information about flora and fauna left reeling from extreme weather events. But these studies (four of which are detailed here) are even more vital as mile markers down the path toward a future besieged by climate change—either as guidance on forestalling it or living better within its confines.

Anna Armitage of Texas A&M Galveston is studying how the transition from salt marsh wetlands to mangroves might change how hurricanes affect the coast. In Texas, low, marshy wetlands are common, whereas dense mangroves are rare. That balance is shifting, however, as climate change heats up these ecosystems. As mangroves expand their footprint, Armitage (and researchers at Florida International University and the University of Houston) wonders if they might offer coastal ecosystems and human settlement more protection from hurricane winds and rain—at a cost of biodiversity. “It probably doesn’t provide the same value for birds, fish, and shrimp,” she says.

Climate Change Big Picture: If mangroves do offer more protection for coastal ecosystems in a climate of increasingly severe storms, then Armitage says the next question is, “Should we be planting them in restoration sites?” These kinds of “living shorelines,” she says, could be “more resilient, longer-lasting, and nicer looking protection for our communities” than concrete barriers.

Grant amount: $122,935

Paul Montagna of Texas A&M Corpus Christi is studying the inundation of fresh water (via rainfall) into saltwater ecosystems that Hurricane Harvey caused. From initial measurements after the rain, he’s observed increased amounts of dissolved organic matter in these waterways, and has seen (more…)

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BY BRIAN BARTH / PHOTOGRAPHY BY JULIE DERMANSKY

In Southern Louisiana, Evans + Lighter Landscape Architecture is helping the people of Isle de Jean Charles move away from a disappearing coast.

Every year LAM honors two articles that stand out in the realm of landscape architecture with the Bradford Williams Medal—one that has appeared in LAM, and one from outside the magazine. After a nomination and selection process by the LAM Editorial Advisory Committee, this year’s 2017 Bradford Williams Medal LAM winner is Brian Barth for his article “Let’s Beat It,” below, which appeared in the October 2016 issue.

Wenceslaus Billiot often spies dolphins leaping in the bay behind his house in Isle de Jean Charles, Louisiana. Just shy of his 90th birthday, he remembers his backyard as a vast, forested wetland when he raised his family here as a young man. In dry weather, the land was firm enough for his kids to walk to the store in the nearby hamlet of Chauvin. This June day the water is calm—a fisherman’s paradise—but hurricane season is another story. Billiot, a World War II veteran, former tugboat captain, and boat builder, says every year the water comes higher.

He lives in a dwindling community of the Biloxi–Chitimacha–Choctaw tribe, and like most of the 27 families who remain, Billiot and his wife, Denecia, are making plans to move inland. “But I don’t want to go,” he says in a Cajun accent.

He has no choice. Isle de Jean Charles, once 22,000 acres, has lost 98 percent of its land area since 1955, and state officials warn that (more…)

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BY TIMOTHY A. SCHULER

Where has all the sediment gone? Image courtesy of Landscape Metrics and the Dredge Research Collaborative.

Where has all the sediment gone? Image courtesy of Landscape Metrics and the Dredge Research Collaborative.

From the December 2016 issue of Landscape Architecture Magazine.

Thanks to a severe shortage of sediment, the tidal marshes of the San Francisco Bay are disappearing, taking with them a vital ecosystem and an important defense against sea-level rise. In response, in June 2016, voters approved a parcel tax that will generate $500 million over the next 20 years for wetland restoration. And yet the sediment hasn’t vanished; it’s a prisoner of the state’s highly altered hydrologic system. “There’s this incredible resource that’s just sitting behind this constellation of dams,” says Landscape Metrics principal Matthew Seibert.

This summer, as a part of DredgeFest California, Seibert worked with the Dredge Research Collaborative and workshop participants to visualize this “hidden sediment reserve.” Based on data published in the journal Water Resources Research in 2009, the team created an interactive map showing where—and when—California’s sediment was diverted, as well as the cost of removing that sediment, which far exceeds the expected $500 million in tax revenue. Seibert is optimistic, however, especially as the economics of climate change become increasingly apparent: “The Baylands have an amazing capacity for flood mitigation that I don’t feel is quantified economically yet, or valued as it should be.”

For an interactive version of this map, visit landscapemetrics.com/dredge.

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The things our art director, Chris McGee, hated to leave out of the current issue of LAM.

Image courtesy of California American Water.

Image courtesy of California American Water.

From “River Reroute” by Lisa Owens Viani in the November 2016 issue; a look at Rana Creek Design’s plans to swap a riverbed for a parallel-running creek so that sediment can be removed from a dam nearing the end of its useful life.

“Busy beavers. . .”

–Chris McGee, LAM Art Director

As always, you can buy this issue of Landscape Architecture Magazine at more than 700 bookstores, including many university stores and independents, as well as at Barnes & Noble. You can also buy single digital issues for only $5.25 at Zinio or order single copies of the print issue from ASLA. Annual subscriptions for LAM are a thrifty $59 for print and $44.25 for digital. Our subscription page has more information on subscription options.

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