Water Has a Memory: Preserving Strawbery Banke & Portsmouth from Sea Level Rise

In 2013, Strawbery Banke was invited to join the City of Portsmouth’s Local Advisory Committee (LAC) for the Climate Change Vulnerability Assessment on Historic Portsmouth. Using data and maps created during the Coastal Resilience Initiative, the committee evaluated the areas of the city most vulnerable to sea level rise and storm surge, based on historic, cultural and property values. 

Now the City of Portsmouth Water and Planning Departments have joined Strawbery Banke to create a major new exhibit, funded in part by the Roger A. and Theresa S. Thompson Foundation. “Water Has a Memory: Preserving Strawbery Banke and Portsmouth from Sea Level Rise” is a major contribution to the effort to educate the public about the damage already being done to the historic landscapes of the Northeast – specifically the Seacoast – from the consequences of sea level rise. Warming oceans are bigger oceans, causing changes in the intensity of storms and the scope of flooding. After flooding from lunar King Tides and storm surges impacts the groundwater beneath Puddle Dock and surrounding historic buildings at the museum and in the South End neighborhood, lingering salt and humidity weaken structural components of wood and brick.

For more details on mitigation efforts, including a timelapse video of groundwater flooding in the Shapley-Drisco House, click here.

The new exhibit, opening in 2021, tells that story over time, introduces the City’s “Think Blue” suggestions for ways individuals can make a difference in mitigating the effects, and showcases a project by the UNH Geospatial Mapping Lab and the City to collect the data needed to define and monitor the problem.

Strawbery Banke Museum’s historic and picturesque location on the banks of the Piscataqua River in  Portsmouth, NH has, unfortunately, placed it in the highest at risk area for impacts of sea level rise (see City of Portsmouth Historic Properties Climate Change Vulnerability Study ).  The impacts from this are already being seen in four of the museum’s 32 historic houses.  These impacts are from both surface water (freshwater) and groundwater (brackish water)[see SBM website.  Further, this exposure to water is already causing rapid decay of these important historic structures. As part of its mission to preserve the buildings under our care has launched the Sea Level Rise Initiative. 

To adequately address the impacts from Sea Level Rise, the museum must understand the full scope of these impacts.   Further scientific study (see Sea-Level Rise Vulnerability Assessment of Coastal Resources in New Hampshire)  will be done to determine water and humidity levels in the effected structures.  Additional research will identify water infiltration points and, working with the City of Portsmouth, identify potential drainage and storm water solutions.  This data will assist the science, engineering and architecture team helping Strawbery Banke design a solution that will take the museum buildings far into the future.

Identified solutions to the impacts will be implemented for all the affected structures.  These will be innovative solutions that balance protecting the historic streetscape and historic preservation of the structures with adequate protection from Sea Level Rise.  Possible solutions include dry proofing basements, creating coffer dams around architectural elements that need protection form water damage and elevating basement access points to keep out surface water.  All solutions will be explored and many will be unique as the museum balances preservation with impact mitigation. 

Strawbery Banke continues to partner with the City of Portsmouth to present analysis and mitigation efforts as a case study in sea level rise effects on historic areas. Strawbery Banke’s Director of Facilities and Special Projects has presented with City representatives at “Keeping History Above Water” national conferences and at a variety of local conferences, Ted talks and to regional history and preservation groups.  COVID-19 precautions have delayed the opening of the exhibit until Spring 2021.