The Boston Green Ribbon Commission just released its 250-page Report on Feasibility of Harbor-wide Barrier Systems, finding that shore-based climate adaptation solutions have significant advantages over harbor-wide strategies for Boston and surrounding communities.
In response to the City of Boston's planning efforts launched in 2016, known as Climate Ready Boston, the Sustainable Solutions Lab of UMass Boston undertook a feasibility study for a harbor-wide flood protection system funded by the Barr Foundation. The purpose of the study was to provide a preliminary assessment of the feasibilities and potential cost, benefit and environmental impact of three specific harbor-wide barrier configurations taking into account potential interference with shipping channels and other harbor uses.
The specific barrier configurations studied included an Outer Harbor Barrier (OHB) from Winthrop to Hull, an Inner Harbor Barrier (IHB) between Logan Airport and the Seaport area of South Boston, and a Metro Dike Barrier from Swampscott to Cohasset. This latter alternative was dismissed due to its impacts on shipping, navigation and fishing. The OHB configuration involved 3.8 miles of gated barrier with an additional 9.3 miles of shore-based protection in Hull, Winthrop and Revere. The IHB system was a shorter length of barrier between Logan Airport and the Seaport, but would require 18 miles of shore-based protection systems to the north and south to function properly.
Detailed analyses of both alternatives are provided in the report, including conceptual designs, cost evaluations, hydrodynamic analysis of tidal attenuation, water velocity and environmental impacts. In addition, the economic analysis evaluated impacts on shipping, recreational use, and potential ecological changes in the abundance, distribution and behavior of fish populations impacting commercial and recreational fishing. Lastly, the report contained a social vulnerability analysis to determine if either configuration had a disproportionate impact on vulnerable populations. All of these impacts were compared to the concept of shore-based adaptation solutions, focusing particularly on cost and timing of implementation.
Based upon these analyses, the report concluded "it is clear that shore-based adaptation strategies, if effective, have significant advantages over harbor-wide strategies for Boston, at least for the next few decades…." Specifically, "while a harbor-wide barrier system could manage some coastal flooding with perhaps minimal environmental impacts and moderate impacts on harbor users, its cost-effectiveness is low and its operational life would be limited." This is due, in large measure, to the limited potential to adapt or adjust the barrier once it is in place and the uncertainties of climate change over time. In short, Boston is not Rotterdam and the Dutch solution, heralded by many, is not likely feasible.
