Sea-level Rise in Boston Harbor – Managing the Risk

Posted in Vol 13 No 2 by bsaab on May 20, 2010

This diagram illustrates high and low projections for global sea-level rise (SLR) over the next century, derived from data contained in the WWF / Allianz Tipping Points Report, 2009. In addition to illustrating the range of potential inundation, the diagram also suggests an answer to the question “How long do we have?”

Assuming that even a modest 12-inch rise in sea level would present a serious challenge to the functioning of a waterfront city such as Boston when added to flood levels currently considered 100-year-flood levels, one can read from this diagram that, in the worst case, this may happen as early as 2024, without taking into account any surge factor. On the lower projection, that scenario may happen as late as 2046, or 36 years hence.

Risk associated with buildings is predicated by both function and lifespan. Institutional buildings are typically designed for a 60-80 year lifespan (or longer), commercial buildings for less than half that period. Since a major infrastructure project may take 25 to 35 years from conception to completion, it is clear that defensive measures are necessary as a short-term precaution while more extensive plans are in process for the longer term.

For any specific application of this diagram, take the current FEMA flood risk (100-year or 500-year) site datum as the base datum and project accordingly. A storm-surge factor must be added to the base datum for sea-level rise. Depending on site exposure, wave action, wind speed and duration, and astronomical extreme tides, the storm surge may add as much as seven to eight feet to sea level. Note: for clarity, the straight-line graph is a simplification of what is in finer detail a curve depicting a geometric progression in sea-level rise over time.

3 Responses

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  1. Richard Keleher said, on May 23, 2010 at 8:26 pm


    I have worked on many commercial buildings in downtown Boston that are 100 years old and still going strong. That’s why I was working on them; to preserve them for more years of service. And they are often beautiful historic buildings. So, I think that the consequences of sea level rise and storm surges is even worse than your chart depicts.


  2. Hubert Murray said, on May 24, 2010 at 10:05 am

    You make an excellent point Richard. I am sorry that I did not conjoin the issue of the risk posed for historic buildings with the point that I made in the article about infrastructure. I would however argue that the inundation of the subway or the highway tunnels poses a far higher urban risk than the flooding of a few basements. That was the lesson of the Paris flood in 1910.
    Responding to your statement that it’s going to be far worse than the chart depicts I would ask (and that includes anybody who reads this) what can you do in the short term (say 5 to 10 years) while you make plans for dealing with the longer term – say 30 years from now?

  3. […] the best-case scenario of the Boston Harbor rising just 2.5 feet; it could rise twice that much, as Architecture Boston showed earlier this year. We can't just load the Kennedy Greenway onto Noah's Park Ark to save it […]

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