- Squeezing more ecological value from the SpongePark™
Even small patches of habitat have great value to urban centers. New York City (NYC) is pockmarked with small spaces, backyards, abandoned lots, small public parks, and roadside verges that together represent threads that can be stitched together to make a living fabric in this metropolitan area. Given the high density of people in NYC, the potential for ecological services and their value is enormous. The Sponge Park™ concept offers a novel way to meet environmental engineering goals while also contributing cultural and habitat advantages.
As Figure 2 shows, the landscape ecology around the Gowanus Canal has been in flux for 300 yr. The original wetland and estuarine borders have slowly been replaced by the complex constructed infrastructure that the people of Brooklyn need. Waterfronts have been bulkheaded, and normal water flows have been replaced by completely engineered pipe systems. The people of this borough are almost completely divorced from the original character and value of this waterway. I take the long view that the next 100 yr will be quite different from the previous 100 yr. There are enough urban greening initiatives bubbling away that our children's city may look quite different from that of our parents. For example, the million tree initiative of the NYC government (www.million treesnyc.org) is well underway, driven by the public health value of trees as well as interest in beautification. The commentary by O'Connor mentions that, even at the small scale, combining Sponge Park™ with green and blue roof elements will yield a higher functioning engineering solution. My interest here is in maximizing the Sponge Park™ design for the wild, living members of the watershed.
The scaling of the treatment wetlands at the street end near the Canal is a critical part of the functioning solution. The volume of water entering the terraces of wetlands may be very high, and this small street end must be sufficient to convey, store, and clean this volume. The exact scaling up of wetland areas to the watershed's drainage is an exercise for future design development. The large watershed area shown in Figure 3 seems to need a composite of engineering solutions to allow the modest area of the street end to function as desired. Volume of storm water from upstreet locations must be intercepted. Reuse and new reclaimed water initiatives may be possible. The built area of this section of Brooklyn is so extensive and so financially successful that additional areas that might be green through removal of pervious paving or buildings of only modest value seems unlikely. However, so many inner city areas throughout this country are struggling. The availability of patches of open space which can contribute to solving environmental concerns through bioengineering approaches may be widespread. Sponge Park™ may be more readily adapted to a Detroit or New Orleans in the next few decades than to hipster Brooklyn.
The actual habitat value of Sponge Park™ has great potential. The website of this design group (www.spongepark.org) shows more biological detail than the article published here. The planting palette of woody species that could be added to the streetscape or to somewhere in the treatment wetlands includes many native species that serve as nesting and feeding sites for urban birdlife. The species, including dogwoods (Cornus spp.), mulberry (Morus spp.), hawthorns (Crataegus spp.), roses (Rosa spp.), serviceberry (Amelanchier spp.), and elderberry (Sambucus canadensis) are known to thrive in NYC and offer much cultural value as well as wildlife habitat. The interest in the designers in urban wetland and estuarine habitat is explicit. The Sponge Park™ website (the menus under design, then habitat and phytoremediation) illustrate dozens of animal species from crabs to chipmunks that might use the restored habitats here. The probabilities of getting a sustainable population of chipmunks next to the wine bars of the Red Hook section of Brooklyn seems low, but there is a high biodiversity of fish and crustaceans in New York harbor, and these could be cajoled into returning to the Gowanus once water quality and microhabitats are improved. The usual homogeneous ground surface of many designed parks should be roughened, made complex...