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. The Massachusetts Office of Coastal Zone Management’s (CZM) 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).
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 typically available for viewing at your Town Hall and online through FEMA’s How to Find Your Flood Map web page. These online resources can help homeowners understand the NFIP and how to read the FIRMs:
- Using a Flood Insurance Rate Map and FEMA tutorial on FIRMs - This factsheet and animated tutorial provide details on using and interpreting the FIRMs, including how to differentiate and 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 Federal Emergency Management Agency (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: Information for Homeowners and Renters - 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 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:
- Storm Surge and Coastal Inundation - This National Oceanic and Atmospheric Administration (NOAA) website features an overview of storm surge, along with information on storm surge impacts, preparedness, forecasts and warnings, models and observations, research and development, event history, and products and resources to help prepare coastal communities and residents.
- Hurricane Surge Inundation Maps - The U.S. Army Corps of Engineers (USACE), FEMA, and NOAA created new hurricane surge inundation maps in 2013 for the Massachusetts Emergency Management Agency and coastal communities to identify vulnerable areas and guide evacuation activities. See the hurricane surge inundation scenarios in the Massachusetts Ocean Resource Information System (MORIS). Previous maps and reports from 1994 and 2000 are still available on the USACE Massachusetts Hurricane Evacuation Studies web page.
- Tidal Flood Profiles - 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.
- Experimental Inundation Viewer for coastal Massachusetts - This interactive map, developed by NOAA, allows visualization of various levels of coastal flooding.
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 file size 3MB - 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 and Coastal Flooding Impacts 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.
- Coastal Inundation Scenarios in MORIS - NOAA's coastal inundation data have been added to the Massachusetts Ocean Resource Information System (MORIS) to allow users to interactively use the sea level rise scenario data with other information such as aerial photographs, assessor maps, public facilities and infrastructure locations, and natural resource areas.
- Boston Harbor Sea Level Rise Maps - These high-resolution maps produced by The Boston Harbor Association show the impact of 2.5 feet, 5 feet, and 7.5 feet of flooding above mean high tide on the Boston Harbor coastline.
- Coastal Areas Impacts and Adaptation - On the U.S. Environmental Protection Agency’s Climate Change website, this web page provides reports on sea level rise, coastal flooding impacts, and changes related to storm surge and precipitation.
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: