Sea Level Rise and Coastal Impacts

June 4, 2014

In late November 2013, the Massachusetts Office of Coastal Zone Management (CZM), in coordination with the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center, held a workshop in Marshfield on mapping coastal flooding impacts. The workshop was targeted towards representatives of local, state, and federal agencies, to better inform regulators on the impacts of climate change when considering design and development of coastal property.

Recently, NOAA added Massachusetts elevation data to its Sea Level Rise and Coastal Impacts Viewer, allowing users to map sea level rise flooding of up to six feet above current levels. Massachusetts coastal areas are particularly vulnerable to sea level rise, because the glacially-formed beaches have very shallow slopes, leading to a large horizontal area of flooding for even a small level of vertical sea rise. The workshop emphasized that the extent of flooding depicted in each scenario is the estimated average of the maximum high tide, and that areas mapped as open water would likely be inundated on a daily basis. The application does not directly take into account storm surge, but does identify inland areas at or below sea level that would be vulnerable to flooding from storm events.

CZM incorporated portions of the NOAA sea level rise scenarios into its Massachusetts Ocean Resource Information System (MORIS) mapping tool, which contains other coastal layers maintained by the Office of Geographic Information. This application allows users to map sea level rise with more local information, such as assessor’s parcels and regulated areas such as fish runs and wetlands, in order to further identify potential flooding impacts. NOAA anticipates releasing photographic renderings of flooding on select local landmarks in the near future.

These sea level rise flooding mapping applications make many assumptions on the future morphology and elevation of the existing coastline; and should not be used to make site-specific decisions. They do however serve as educational tools that can assist in visualizing the effects of climate change, so that Massachusetts communities can prepare for the future. Keep an eye on CZM’s Coastal Calendar for additional workshops in your region on sea level rise mapping and other topics.

Sea Level Rise in Boston

NOAAs estimated flooding resulting from a 6’ sea level rise in Boston Harbor


Eric Las is a Principal at Beals and Thomas, Inc. in Southborough, MA.