In an increasing number of communities along the Massachusetts coast, erosion and flooding are causing damage even during minor storms. As a coastal property owner, assessing your property’s vulnerability to storm waves and flooding can greatly enhance your ability to address these and other storm damage problems. CZM's StormSmart Coasts program has assembled the following information on this topic, organized into the following categories:
- Erosion Rates
- Floodplain Maps and Flood Insurance
- Storm Surge and Coastal Inundation
- Sea Level Rise
- Storm Tracking
The loss (erosion) and gain (accretion) of coastal land is a visible result of the way shorelines are reshaped by dynamic coastal conditions. To help make informed and responsible decisions, shorefront landowners need information on both current and historical shoreline trends, including reliable measurements of erosion and accretion rates.
- Massachusetts Shoreline Change Project - This CZM site links to an interactive shoreline change browser showing the relative positions of historic shorelines, along with information on erosion since the mid-1800s.
- South Shore Coastal Hazards Characterization Atlas - While developed for coastal managers, this atlas (which covers the South Shore from Hull to the Cape Cod Canal and was prepared for CZM in 2005 by Applied Coastal Research and Engineering, Inc.) provides technical information of potential interest to homeowners. In addition to short-term shoreline change maps, topics covered include: shoreline type, beach width fronting coastal banks, and tide range, wave climate, and storm susceptibility (for the entire coast of Massachusetts) and relative sea level (for the northeastern coast).
Floodplain Maps and Flood Insurance
As part of the National Flood Insurance Program (NFIP), the Federal Emergency Management Agency (FEMA) produces Flood Insurance Rate Maps (FIRMs) to show the areas that are predicted to flood in a storm event having a 1% chance of occurring in a given year (also called the 100-year storm). FIRMs are available in in the Massachusetts Ocean Resource Information System (MORIS) and are also typically available for viewing at your Town Hall and online through FEMA’s Flood Map Service Center. These online resources can help homeowners understand the NFIP and how to read the FIRMs:
- How to Read a Flood Map – This tutorial provides details on locating, using, and interpreting the FIRMs, including how to delineate flood zones on coastal properties.
- Interpreting Federal Emergency Management Agency Flood Maps and Studies in the Coastal Zone - Updated in 2017, this publication developed by CZM in cooperation with the Department of Conservation and Recreation’s Flood Hazard Management Program, provides guidance on how to use FEMA Flood Maps and Studies to better understand the potential effects of flooding on buildings, properties, and the underlying natural resource areas. This information can be used by homeowners and consultants to ensure that the safest possible coastal projects are designed, as well as by public officials to successfully evaluate projects to ensure they are designed to minimize storm damage, protect public safety, and reduce the financial burden on individuals and municipalities from losses due to coastal storms.
- Tools to Assist in Interpreting Flood Insurance Rate Maps and Flood Insurance Study Reports - This StormSmart Communities web page describes how to use, interpret, and recognize the limitations of FIRMs and FIS reports.
- National Flood Insurance Program Overview - This FEMA web page provides links to information about flood preparedness and flood insurance, estimating premiums and filing claims, determining your flood risk, and viewing and obtaining flood maps.
Storm Surge and Coastal Inundation
Storm surge is the rise in water level caused by a severe storm, such as a hurricane or northeaster. The advancing surge combined with wind and normal tides increases the effective sea level and can create extensive storm damage. Coastal inundation is the flooding of normally dry, low-lying coastal land, primarily caused by severe weather events along the coast, estuaries, and adjoining rivers. See the following links for information on the potential impacts of storm surge and coastal inundation on the coast:
- Hurricane Surge Inundation Maps - The U.S. Army Corps of Engineers (USACE), FEMA, and NOAA created worst-case scenario hurricane surge inundation maps and evacuation zones in 2013-2014 for the Massachusetts Emergency Management Agency and coastal communities to identify vulnerable areas and guide evacuation activities. Explore the inundation zones in MORIS or the MassGIS map service. The USACE Massachusetts Hurricane Evacuation Studies web page also provides the maps, reports, and GIS layers for download.
- Tidal Flood Profiles (PDF, 1 MB) - The New England Division of USACE prepared tidal flood profiles in 1988 for historic coastal storm events to illustrate total water levels (tide plus surge plus wave elevations) relative to FEMA 100-year, 50-year, 10-year, and 1-year flood elevations along the New England coast.
- Coastal Flood Threat and Inundation Mapping viewer - This interactive map, developed by NOAA's National Weather Service, allows visualization of minor to major coastal flooding forecasts for Massachusetts.
Sea Level Rise
Sea level rise refers to the increase in mean sea level over time. Sea level has been rising in Massachusetts for thousands of years since the retreat of the last glaciers over 20,000 years ago. During the last century, tide gauges and satellites indicate an acceleration of sea level rise relative to the past rate. For more information on current trends and potential future change in sea level, see the following:
- Sea Level Rise: Understanding and Applying Trends and Future Scenarios for Analysis and Planning (PDF, 3 MB) - A guidance document to help coastal communities and others plan for and address potential sea level rise effects on residential and commercial development, infrastructure and critical facilities, and natural resources and ecosystems. The document includes background information on local and global sea level rise trends, summarizes the best available sea level rise projections, and provides general guidance in the selection and application of sea level rise scenarios for coastal vulnerability assessments, planning, and decision making for areas that may be at present or future risk from the effects of sea level rise. The document is intended to be updated as new science and information becomes available.
- Sea Levels Online - This NOAA website provides plots of three tide stations along the Massachusetts coastline (Boston, Woods Hole, and Nantucket) showing monthly mean sea levels (without seasonal fluctuations) and long-term linear trends. Regular seasonal fluctuations and irregular yearly fluctuations can also be viewed separately.
- Sea Level Rise Viewer - Developed by NOAA, this tool provides a visualization of the potential impacts of sea level rise on coastal communities. Massachusetts coastal communities can view six scenarios of future high tides, uncertainty maps, and information on marsh migration, social vulnerability, and flood frequency. These data—in conjunction with the Massachusetts Coast Flood Risk Model, FEMA flood zone maps, and Sea, Lake, and Overland Surges From Hurricanes (SLOSH) model—are available in both MORIS and the Massachusetts Sea Level Rise and Coastal Flooding Viewer.
- Climate Ready Boston Map Explorer - This map viewer displays data created for the Massachusetts Department of Transportation’s (MassDOT) Central Artery and Tunnel Vulnerability and Adaptation Assessment in 2015 identifying predicted coastal flood risks and flood depths from coastal storms and sea level rise. Three time frames (2013, 2030, and 2070) and three flooding scenarios are provided. The 2015 coastal flood maps and the 2010 Boston Harbor flood maps produced by The Boston Harbor Association (using a “bathtub” model) are also provided on the Boston Harbor Now web page. For more information on the flood risk model and assessment, see the MassDOT web page.
- Resilience and Adaptation in New England (RAINE) - This U.S. Environmental Protection Agency database of climate change resources provides reports on sea level rise vulnerability as well as resilience and adaptation across the New England region.
Coastal property owners likely to be impacted by storms, waves, tides, and wind can keep informed of current coastal conditions and predicted storms. For links to storm-related information, see these two CZ-Tips: