As long-time, year-round coastal residents can attest, coastal landscapes are forever changing, and many places that seemed safe for building 10 years ago are now regularly underwater during minor storms. Many sources now predict that the frequency and power of storms will increase in the future (including a 2007 report by the Union of Concerned Scientists (PDF, 537 KB) suggesting what is now called a 100-year flood in Boston is expected to occur, on average, as frequently as every two to three years by mid-century, and once every other year by late-century). When using coastal flood data, especially Flood Insurance Rate Maps (see understanding the limitations of Flood Insurance Rate Maps and Flood Insurance Study reports), be sure to consider future flooding scenarios. Your community may also wish to include accommodations for future coastline changes and effects of sea-level rise, subsidence, or increased development in the floodplain in its regulatory language. (For example, prohibiting the construction of new buildings in areas where they are likely to be threatened by erosion during their design lives.)
See the following resources for information on future coastal conditions:
- For an example of a bylaw incorporating projected sea level rise, see the Cape Cod Commission’s Model Bylaw For Effectively Managing Coastal Floodplain Development (PDF, 1.1 MB).
- The Massachusetts Historic Shoreline Change Project provides shoreline change maps for each coastal community in the Commonwealth.
- The South Shore Coastal Characterization Hazards Atlas provides more detailed and recent information for South Shore communities (between Hull and the Cape Cod Canal), as well as additional information that covers the entire state (e.g., information on sea level rise).
- Preparing for Climate Change: A Guidebook for Local, Regional and State Governments is a detailed study on how local governments can best adapt and respond to climate change.
* Your community needs only 500 points to qualify for reduced flood insurance premiums through the Community Rating System (CRS). For more information (including how to apply for the CRS program), see our Community Rating System (CRS) primer.
Notes from the folks at CRS:
“Coastal erosion mapping and setback regulations are one way coastal communities protect property from future conditions. The publication, CRS Credit for Management of Coastal Erosion Hazards, describes how coastal communities can receive up to 575 points for coastal erosion mapping and regulation.”