Mapping of Flood Potential in Boston

In this presentation segment I’m going to
focus on what climate change science and scientific modeling tell us about sea level rise in the
Boston area. I’m going to take a distinctly local perspective on sea level rise, and share
maps and models of potential flood areas in Boston, then discuss mitigation and adaptation
strategies. We developed the maps that I will be showing you using the discrete heights
for sea level rise that were presented in the previous segment; 2.5 feet of sea level
rise representing approximately the higher projections for mid-century, and 5 feet of
sea level rise representing approximately the higher projections for the end of the
century. Additionally, we mapped a five foot storm surge on top of sea level rise which
represents approximately the current 100-year coastal flood in Boston. And all of these
maps represent a WICKED high tide, the bi-monthly astronomical high tide. These maps are two
dimensional representations of a three dimensional phenomena, so what we use for our symbology
is a profile view (a side view) of the maps, which are shown from an aerial view (the view
from above) So, on the maps I’ll show, areas shown in the pale yellow indicate flooding
of up to two feet of water The red areas on these maps depict two to four of flooding.
The mustard color areas represent flooding of four to six feet. The dark blue areas represent
the areas of deepest water without regard to specific depth. The map shown here represents
the worst of what Boston experience during Hurricane Sandy; approximately a two and half
foot sea level rise above the normal height of a WICKED high tide. Sandy’s storm surge
at high tide in Boston was just lapping at the shores. If you look carefully you can
see a little bit of pale yellow (less than two feet of flooding) down around the edge
of the waterfront. There’s two other ways of looking at this map. This first is that
mid-century, some time, when we’ve experienced two and half feet of sea level rise, at WICKED
high tide, the fringes of the Boston waterfront will flood regularly. Morrissey Boulevard,
for example, on the other side Savin Hill Bay, will be much more flooded than it is
now, twice a month, a high tide. Another way of look at this map is that it could also
represent a current small coastal storm that generates 2.5 feet of surge on top of a WICKED
high tide. Now let’s look at the map of flooding during WICKED high tide after a 5 foot sea
level rise, projected to occur approximately at the end of the century. We can also look
at this map in several ways. Under the higher sea level rise scenario, this map shows the
twice monthly WICKED high tide in Boston by the end of the century. Another way of look
at this map is that it approximates today’s current 100 year flood. On this map you can
see you starting to see flooding in areas of the city that were created by historical
landfilling. One important thing about this map is the Charles River Dam. The Charles
River Dam was designed to deal with today’s hundred year flood. It will not currently
flood in the Back Bay during a hundred year coastal storm, but consider what could happen
with future sea level rise. Now we’re going to look at them all together. Here we see
our model of 2.5 feet of sea level rise with a five foot storm surge during a WICKED high
tide, which shows the overtopping of the Charles River Dam which will then flood Back Bay and
Cambridge. This map shows that Boston could become very vulnerable to coastal flooding
by approximately the year 2050. This would be a good time to address Adaptation and Mitigation.
We should start with a definition of terms. Mitigation is what we all need to do. We need
to stop emitting carbon dioxide, at some point, hopefully sooner than later to mitigate this
problem. We have to solve the problem of excess carbon dioxide in the atmosphere. Adaptation,
which is what our research group focuses on, addresses the fact that climate change and
sea level rise are already happening, and likely to continue on in the foreseeable future..
We need to figure out how to live with this, especially in coastal cities. Our research
focuses on the hard structures of the city, specifically Boston, and specifically sea
level rise. But these adaptation concepts can be applied to many types of situations.
One of the challenges we deal with in adaptation science is the uncertainty. We saw earlier
on the sea level rise graph that the further you go out into the future the more uncertain
we are about when and how much sea level rise will occur. So we need to be able to respond
both in different locations as well as over different time periods and we need to include
all the stakeholders. We need adaptation options that are flexible, adjustable and robust so
that no matter what happens in the future the solutions that we implement are solid.
The other piece is to integrate adaptation with sustainability planning. While you’re
adapting why not do a little mitigation at the same time. Consider involving things like
green roofs and consider other strategies and activities that you can build into adaptation
planning. The new Spaulding Rehabilitation Hospital in Charleston is a great example
of these types of integrative adaptation strategies. When the hospital committed to building on
the water in Charleston they acknowledged the problem of sea level rise right up front
during the planning process. Their engineers determined what would be their hundred year
flood elevation in the year 2085 and they located all of their key floors above that
elevation. Every area below that is not critical; a flood can damage it and it wouldn’t stop
the primary missions of the hospital. Even better, mechanical, electrical and emergency
services are on the roof, isolated from the flooding and the waves during a coastal storm.
All operative windows are keyed to open in the event of systems failures. That’s a direct
response by hospitals designers to Hurricane Katrina where they had to break windows to
get fresh, healthy air for patients when the power went out. I’ll finish this presentation
with one of our key findings for the Preparing for the Rising Tide in Boston report; that
we need to coordinate adaptation planning among all sectors of the community because
no one group or organization has the resources, knowledge and authority to complete the task
alone. I’ll leave you my personal favorite adaptation credo: “Prepare and monitor.” Start
researching and evaluating the potential problems NOW, develop plans NOW for how to adapt to
these issues in the future, and then when the tide gauge tells us that the sea level
has reached a critical threshold, then implement the plans that have already been developed.

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