Protective sand islands in long narrow threads would run along the Atlantic seacoast from Cape Cod, Massachusetts, to Cape May, New Jersey, in one of the most ambitious proposals unveiled last week by Rebuild by Design. The program is a high-speed, invited competition sponsored by a presidential task force, guided by the U.S. Department of Housing and Urban Development (HUD), and supported by the Rockefeller Foundation and others. The islands were among the strategies proposed by 10 interdisciplinary teams, to rebuild after Hurricane Sandy and protect against flooding due to rising seas and more violent storms.

“The task force brings innovative resilience, not just for individual cities, but across the region,” said Henk Ovink, the senior advisor to HUD secretary Shaun Donovan at the unveiling in Lower Manhattan. The cordon of islands, called Blue Dunes, would absorb wave energy and reduce the height of the storm surge on the order of five feet. It was proposed by an interdisciplinary team led by WXY Architecture and Urban Design, of New York, and the Dutch landscape architecture firm West 8. “We asked, how do we get away from building high flood walls everywhere?” said WXY principal Claire Weisz.

HUD did not hand out a competition brief, but instead asked the teams (made up of 200 professionals that include scientists, real-estate advisors, academic institutions, and citizen advocates) to consult with communities affected by 2012’s Hurricane Sandy. Hunts Point, a Bronx neighborhood home to a massive, regional food-distribution facility, promoted the Rebuild effort of Philadelphia’s PennDesign and landscape architecture firm Olin with a "Slam Bake" (a chef cook-off). Not to be outdone, New Jersey Rebuild participants staged a parade in Asbury Park.

All but the WXY team developed detailed solutions for individual communities, from Bridgeport, Connecticut, a declining industrial city where river floods meet ocean storm surges, to Asbury Park, a reviving beach town where flood waters swamped Art Deco beach pavilions. Their solutions could redefine Americans’ relationship to the water’s edge. Instead of sea walls and rock groins, the Rebuild teams deployed sea grass, dunes, breakwater habitats, and marshlands to shatter waves, restrain floodwaters, and steer sand-bearing ocean currents.

A team led by Bjarke Ingels's firm BIG redesigned the sea wall to terrace up from the water and terrace down to grade, integrating a variety of public, commercial, and landscape amenities that adapt to conditions block by block. Panels would deploy from the underside of the Franklin D. Roosevelt East River Drive to form a flood wall, when needed.

Instead of visionary ideas or grand plans, the teams offered suites of tactics that create flood protection, urban amenity, and economic development benefits. Many ideas could be adapted to the mix of salt marshes, estuaries, and barrier islands that stretches along most of the Atlantic coast. A team led by the real-estate advisory firm HR&A and the urban-design firm Cooper Robertson (both of New York) focused on upgrading retail strips, which are the lifeblood of beach towns. New Jersey’s densely built-up but highly vulnerable barrier islands generate $28 billion annually, showing just how high the stakes are.

Waggonner & Ball, of New Orleans, with Mississippi firm unabridged Architecture, brought Hurricane Katrina experience to bear in Bridgeport, leveraging the economic-development potential of the fading industrial city by upgrading the 20 percent of land that is in a flood zone. Raised infrastructure corridors would act as levees, protect vital services, and create safe evacuation routes.

Breakwaters are gaining favor over seawalls. A team led by the New York landscape architecture firm Scape proposed “habitat breakwaters” off the south shore of Staten Island. Principal Kate Orff said they would dramatically reduce the velocity of storm-driven waves. “Velocity was key to deaths in Staten Island,” she said.

Designers shaped dunes to shatter wave forces and grab drifting sand, and connected them to inland bioswales that retain water while hosting wildlife. A consortium of Sasaki Associates, New Jersey’s Rutgers University, and the international engineering group Arup proposed a boardwalk edge that vanishes into a dune.

In bays and along streams, terraced, landscaped berms that similarly mix amenity and protection take the place of rock walls and sheet-pile bulkheads. In Bridgeport, Long Island, and New Jersey, stream meanders and oxbows would slow flow. Expanded and enhanced marshlands would retain water, filter pollutants, and gradually allow drainage.

The teams rarely acknowledged moving people away from places likely to be permanently inundated within decades, such as barrier islands, because so-called “managed retreat” involves costly buyouts and politically toxic eminent domain. Both the Sasaki team and one led by Interboro Partners proposed upland redevelopment that could be made appealing to beach dwellers by upgrading streams, lakes, and transportation links.

A jury has been evaluating pilot projects proposed by the teams, who have developed detailed plans and cost estimates, and will recommend some of them to Secretary Donovan. He will choose which ones to finance with block grants and other public and private financing. The designs can be viewed at rebuildbydesign.org.

James S. Russell wrote The Agile City: Building Well Being and Wealth in an Era of Climate Change. He blogs at jamessrussell.net.