Historic Properties Climate Change Vulnerability

Photo of Gates Street Historic Houses
Gate Street, Portsmouth, NH

Supported by funding from the National Park Service (NPS) under the Hurricane Sandy Pre-Disaster Mitigation grant program the State of New Hampshire Division of Historic Resources, the City of Portsmouth completed a Historic Resources Climate Change Vulnerability Assessment and Adaptation Plan. On the heels of a Coastal Resilience Initiative in which the City mapped areas most vulnerable to sea level rise and severe coastal storms, this study incorporated results of the 2016 Downtown Historic Register District property inventory with the City’s 3-D Massing Model and the City’s property valuation database to develop an economic and cultural valuation of its historic properties. The valuation methodology used economic, historic, cultural and flood water vulnerability measurements to characterize, risk-assess and prioritize key historic assets in the City. The project integrated the quantitative data (e.g., flood elevation, topography, structure-type, and economic value) with the qualitative data (e.g., historic survey forms, National Park Service designations) to develop a Historic Resource Valuation and Risk Assessment Map.

The project also focused on four target areas to evaluate the economic impact of flooding and sea-level rise in a variety of land uses and settings. Strawbery Banke, a national historic monument representing early colonial settlement in northern New England, was carefully evaluated for both sea-level change and rising groundwater or seepage impacts to the historic structures. An older section of the South End neighborhood was also assessed and included private, historically significant homes; a first-period cemetery; and the culturally significant Prescott Park. In the downtown, the study evaluated impacts of sea-level rise for the working waterfront, where both commercial and industrial uses continue to operate and depend on land-side, support services. An area of historically significant homes and cemeteries along the North Mill Pond was additionally studied with the notion that adaption strategies will have broad applicability to the larger Mill Pond areas in downtown Portsmouth.

The study involved a multidisciplinary team of local and regional practitioners who integrated a wide variety of economic, environmental, cultural, historic (including archeological) and engineering factors. Using innovative visualization, valuation, and modeling tools the team developed a method with broad-based applicability to other coastal communities to promote resiliency.