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Monday, August 11, 2014

Breakwater-island projects protect people, ecosystems

Black Crowned Night Heron

HARC studying ways to protect people and ecosystems of Galveston Bay

"Black Crowned Night Heron" by Calibas, licensed under CC BY 3.0

Breakwater islands – a possible storm-mitigating strategy for Galveston Bay that HARC is studying – comprise a key element of projects constructed and planned elsewhere to protect people and ecosystems.

Shamrock Island Preserve in Corpus Christi Bay is one of the most important colonial bird-nesting islands on the Texas coast. Nineteen bird species, including the state-threatened reddish egret and white-faced ibis, nest on the 110-acre island preserve each year.

One such initiative that was designed to be part of the New York area’s ambitious, multifaceted response to Hurricane Sandy, received a big boost recently, as the Staten Island Advance newspaper reported in June:

As the region looks to become more resilient in the face of future storms like Hurricane Sandy, in Staten Island, planners are looking to the borough's past to do so – with a $60 million living reef off the shore of Tottenville harkening back to the borough's oyster farming days.

A Living Breakwater project designed by SCAPE Landscape Architects was among the winning projects for the Department of Housing and Urban Development's Rebuild by Design contest, and the state will receive $60 million from HUD to implement it along the South Shore coast.

"The proposal is going to create a living breakwater that will reduce wave action and erosion and lower risk from heavy storms," HUD Secretary Shaun Donovan said. "It also includes a plan to engage the local schools to help build resilience awareness in the community."

The SCAPE firm’s own description of the project includes these details:

The Living Breakwaters project reduces risk, revives ecologies, and connects educators to the shoreline, inspiring a new generation of harbor stewards and a more resilient region over time.

Staten Island sits at the mouth of the New York Bight [an indentation along the Atlantic Coast], and is vulnerable to wave action and erosion. Rather than create a wall between people and water, our project embraces the water, increases awareness of risk, and steps down that risk with a necklace of breakwaters to buffer against wave damage, flooding and erosion. We have designed “reef street” micro-pockets of habitat complexity to host finfish, shellfish, and lobsters, and also modeled the breakwater system at a macro scale to understand how and where they can most effectively protect communities. This living infrastructure will be paired with social resiliency frameworks in adjacent neighborhoods.

Protecting a Texas island habitat

On the Central Texas coast, a series of related projects including breakwaters have been undertaken since 1999 to protect and enhance wildlife habitat on the 110-acre Shamrock Island in eastern Corpus Christi Bay.

Shamrock, one of only four natural islands on the Texas Coast, has been owned by the nonprofit Nature Conservancy since 1995.

Reporting in early 2012 on the latest Shamrock Island project, the Corpus Christi Caller-Times provided this historical summary of earlier stages:

In 1998-99, a partnership of state agencies and conservation programs spent nearly a million dollars to protect parts of the island with a geotube or wave barrier to stave off erosion that had washed away about 500 feet of nesting beach. And they created 2.5 acres of salt marsh on the island.

In 2006, the city constructed 11 rock breakwaters to encourage seagrass growth on the northwest side of the island as part of a mitigation agreement attached to the dredging of Packery Channel.

The Nature Conservancy’s website stresses the island’s ecological value:

Shamrock Island Preserve in Corpus Christi Bay is one of the most important colonial bird-nesting islands on the Texas coast. Nineteen bird species, including the state-threatened reddish egret and white-faced ibis, nest on the 110-acre island preserve each year.

Grassland plants and shrubs help stabilize the dunes and other substrates, slowing wind and water erosion. Seagrass meadows provide essential forage for redhead ducks and nursery, foraging and refuge areas for many estuarine fish and invertebrates. Terrestrial plant communities on the site provide habitat components (nest sites, food) and shelter many resident and migratory species.

The Texas General Land Office, which took the administrative lead in safeguarding the island through a partnership of agencies and organizations, describes Shamrock’s history leading to that multi-stage work:

The island was formed as a spit and was once connected to Mustang Island by the “land bridge” as its north end, but became detached following construction of navigation channels through the island in approximately 1951 and erosion by Hurricane Celia in 1970. Since detachment from Mustang Island, the north and northwest areas of Shamrock Island have experienced considerable beach erosion and loss of wetlands, losing approximately 17 acres between 1950 and 1997. Without proactive measures, this trend of erosion would have continued, resulting in the loss of all valuable habitats found on the Island, including submerged and emergent wetlands, beach areas, and adjacent uplands.