The Rise (and Fall) of the Constructed Coastline

by Stephanie Goldberg

News that Jakarta will be moving completely to a new city location in Borneo within the next  10 years should give us all pause. Though Boston is considered one of the better prepared cities when it comes to climate change induced storms and tides, rising sea levels pose a long term threat.

Zaha Hadid Architects recently completed a revamped Riverwalk section in Hamburg as a barrier against the rising Niederhafen River. According to Lizzie Crook at Dezeen, the flood protection includes dikes, tidal gates and pumping stations.  While the barrier is high (7.2 meters), the design invites pedestrians closer to the water’s edge through dynamic, serpentine stairways.  It is this multi-leveled approach to the connection of land to water that is critical to a successful protective landscape.

In our research on how to protect Boston over the long term, we are looking carefully at this very intersection.  If a barrier must be high to protect against rising seas, how do we treat these junctions so that we do not feel we are up against a wall?  The Blue Necklace of protective inner islands that we have been proposing looks both back to the city and out to the harbor, thus creating opportunities for multiple approaches.  Our datum line for the new islands is 20 feet above Boston’s current shoreline.  Looking back to the city, the design approach has much in common with Hamburg’s Niederhafen Riverwalk.  Elevated plazas and steps down to an inner harbor set the stage for an urban pedestrian life.  On the opposite side, facing the sea, the shoreline becomes more gradual, established to restore sea grasses and other native planting and to create a natural buffer, bringing the feel of our current harbor islands closer to home.

The proposal is to use the same technique to build these barrier islands as has been used along Boston’s harbor.  Piles driven into the soil support a steel sheeting system which in turn protects a pier system.  There are other solutions to explore, however this existing system has the benefit of allowing water to continue to flow between the harbor and newly created inner ring of water.  It is essentially conceived as a floating neighborhood, tied to a location and level that works to create the barriers needed.  Critical to this design, as in the work in Hamburg, is to establish a system of locks, pumping stations and bridges which allow for the water to be readily refreshed, provide pathways for boats and maintain an active connection between the current Boston waterfront and the sea.

In visiting major cities that have grappled with protecting their buildings from an ever changing sea in the past, one realizes that the current coastline is really a construct in time.  Rotterdam’s Delfshaven has newer land directly in front of the pier from where the Pilgrims sailed.  Boston’s edge has changed continually to new conditions, and can continue to do so, while remaining a key part of our vibrant coastal city.