Technical staff recommend 2050 target for sea‑level mapping; commission to compare models

Commission technical staff advised the Eastham Conservation Commission on model and data choices the town could use to define the Coastal Resilience Zone and design flood elevation (DFE).

Shannon Holst said the recommendation is to use the Massachusetts coastal flood‑risk model with a 2050 target year as a reasonable design life for town regulations. She noted different modeling options — DFE, sea‑level rise plus base‑flood elevation, or building‑code freeboard — and cautioned that some data sources incorporate freeboard differently. “The building code currently has BFE plus 3 feet for the coastal B and A zones,” she said, urging the commission to ensure local regulations are at least as stringent as the code.

Commissioners asked for a comparative matrix showing FEMA language, building‑code requirements, DEP draft regulations and the commission's proposed language so staff, the zoning task force and town council can cross‑reference terms and avoid confusion. Karen said she will prepare a matrix to help the zoning task force and permit applicants understand how terms align across sources. The commission agreed to continue model discussion and to loop in additional scientific review when they next consider flood‑model selection.