¨With the incredible destruction in New Jersey and New York, talk is now heating up about how to invest billions to make cities and coastal communities climate resilient and protect them from future storms. The innovative ideas of Dland studio to create wetlands around the city and landscape architect Kate Orff, ASLA, SCAPE, to mitigate storms with man-made oyster reefs were even just featured in a cover story in The New York Times, while the case for using green infrastructure to deal with heavy rain has now gotten more attention thanks to Kaid Benfield’s excellent piece. However, will policymakers now see the value of putting natural systems in place to address flooding and storm risks, or will New York City and others invest in expensive, “hard” infrastructure like sea walls that often fail to do the job of protecting people and property?
A 2009 report by the Army Corps of Engineer and Port Authority of New York and New Jersey looked at the feasibility of recreating 18,000 acres of tidal wetlands “on the margins of the islands and the coastline, [which] act like sponges, slowing and baffling tidal forces,” to replace the massive sea walls, which had actually taken the place of the original 300,000-acre wetlands in the outer boroughs of New York City. The problem the engineers were looking at: sea walls don’t actually function that well when protecting areas below sea level (see New Orleans and Katrina). The original perceived benefit of the sea walls was that they would enable more land to be developed closer to the water.
A proposal by Dland Studio and Architecture Research Office would put a set of wetlands around lower Manhattan and we would hope all the other boroughs. The New York Times writes: “To prevent incursions by water, Mr. Cassell and his planners imagined ringing Lower Manhattan with a grassy network of land-based parks accompanied by watery patches of wetlands and tidal salt marshes. At Battery Park, for instance, the marshes would weave through a series of breakwater islands made of geo-textile tubes and covered with marine plantings. On the Lower East Side of the island, Mr. Cassell and his team envisioned extending Manhattan by a block or two — with additional landfill — to create space for another new park and a salt marsh.” A complementary set of green streets would also boost absorptive capacity within the city.
Another exciting proposal by Orff would use oysters to create decentralized storm mitigation infrastructure in the low-lying Buttermilk Channel and Gowanus Bay that swelled and severely flooded some neighborhoods during the storm. Orff’s argument is that “the era of big infrastructure is over” and needs to be neighborhood-centric and actually embedded into daily life. The New York Timeswrites: “Ms. Orff’s proposal [...] envisions a system of artificial reefs in the channel and the bay built out of rocks, shells and fuzzy rope that is intended to nurture the growth of oysters (she calls them ‘nature’s wave attenuators’).” The reefs would also help clean the water: each oyster purifies an amazing 50 gallons of water a day. Students at a local NYC school have also picked up on the oysters idea and area doing their own experiments to see how they would work.¨