State of the Beach/State Reports/RI/Beach Erosion
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7% of Rhode Island's shoreline is critically eroding, according to the report "State Coastal Program Effectiveness in Protecting Natural Beaches, Dunes, Bluffs, and Rock Shores" (T. Bernd-Cohen and M. Gordon), Coastal Management 27:187-217, 1999. Rhode Island coastal management staff believes that this figure is very low, based on their own calculations.
Critical erosion areas are defined by the state based on annual estimated erosion rates and measured erosion rates for the period 1939 to 1985, as follows:
|Erosion Rate (feet/year)
|2 – 2.5
|3 – 4
|4 – 5
|5 – 6
Barrier beaches that protect salt ponds between Westerly and Narragansett from the Atlantic Ocean are receding at the rate of 2 to 3 feet per year. The annual average erosion rate range in Rhode Island has been reported to be 0-4 feet/year. However, coastal erosion is episodic. Tens of feet of erosion can occur during a severe storm, followed by several years of no net erosion.
For example, when Hurricane Bob passed over Rhode Island in August 1991 it caused a storm surge of 5 to 8 feet along the Rhode Island shore. Extensive beach erosion occurred along the shore from Westerly eastward. Some south-facing beach locations on nearby Martha's Vineyard and Nantucket Islands, Massachusetts lost up to 50 feet of beach to erosion. Rainfall of over 7 inches affected western Rhode Island and extreme eastern Connecticut.
The Rhode Island Geological Survey is a source of information beach erosion and coastal hazards-related issues in Rhode Island. It is affiliated with the University of Rhode Island College of Environmental and Life Sciences, Department of Geosciences program. Unfortunately, the Rhode Island Geological Survey website seems to have very little coastal erosion data and information.
Rhode Island Geological Survey
9 East Alumni Ave., 314 Woodward Hall
University of Rhode Island
Kingston, RI 02881
Jon C. Boothroyd, State Geologist
The Coastal Resources Management Council has adopted new shoreline change maps from Narragansett to Little Compton inclusive of Narragansett Bay and its islands. These new maps are supplemental to those already incorporated into the RI Coastal Resources Management Program for the south coast between Watch Hill and Narragansett Pier. The purpose of these maps is to delineate shoreline rates of change that will be applied to pertinent sections of the Council’s regulatory programs to address issues including setbacks of activities from coastal features. These shoreline change maps detail erosion rates for the shoreline, and are further detailed into shoreline segments for each map. In total there are 150 such maps, which are herein incorporated as regulations of the RICRMP. A map for Block Island has not yet been developed, however, setbacks and erosion rates for Block Island shall be assessed on a case-by-case basis.
The shoreline change maps for Narragansett to Little Compton can be examined at the Council’s office in Wakefield, at the secretary of state’s office, and on-line at the Council’s Website. These maps are on an orthophoto base.
The following published reports have coastal erosion data or information:
- Boothroyd, J. C., Dacey, M. F., and Rosenberg, M. J., 1986, Geological Aspects of Shoreline Management; A Geological Summary for Southern RI. I. Regional Depositional Systems and a Long Term Profiling Network. Vol. 1M. University of Rhode Island, Kingston, RI
- Boothroyd, J. C., Galagan, C. W., and Graves, S. M., 1986, Advance and retreat of the southern Rhode Island shoreline, 1939-1985; including 1985 berm volume; Masters Thesis, University of Rhode Island, Kingston, RI
- Calabro, Rachel B., 1997, Coastal geologic hazards and future shoreline change, southern Rhode Island shoreline : implications for management. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 129 p.
- Dein, M. G., 1981, A quantitative, photogrammetric analysis of Narragansett Bay, RI shoreline changes, 1938-1975; Master Thesis, University of Rhode Island, Kingston, RI,
- Galagan, Christopher W., 1990, The effect of future sea level rise along the southern Rhode Island coast. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 66 p.
- Gibeaut, James C.,1986,Beach sedimentation cycles (1962-1985) along a microtidal wave-dominated coast : South shore of Rhode Island. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 153 p.
- Graves, S. M., 1990, Morphotomology of Rhode Island Barrier Shores : A Method of Distinguishing Beach from Dune/Barrier Component Histories Within a 29 Year Record of Shore Zone Profile Data, with Special Reference to the Role of the Beach as a Buffer and Modulator of Erosional Coastline Retreat. Masters Thesis, University of Rhode Island, Kingston, RI
- Harwood, R. A., 1993, Coastal Processes, Sedimentation Patterns, and Sea-level Rise along a Barrier Island and Upland Shoreline, Narragansett, Rhode Island. Masters Thesis, University of Rhode Island, Kingston, RI.
- Klinger, Joseph P., 1996, Sedimentary environments and processes on the Charlestown-Green Hill barrier/headland shoreface and Misquamicut barrier. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 114 p.
- Newcomer, Denis, 1991, Effect of future sea level rise on barrier migration and headland erosion along the southern coast of Rhode Island. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 131 p.
- O'Connor, Sarah A., 2002, Storm impact on shoreline change : South shore, Rhode Island. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 263 p.
- Sakalowsky, Peter P. Jr., 1972, Relationships between dynamic nearshore processes and beach changes within the intertidal zone of Napatee Beach, Rhode Island. Thesis (Ph.D.)--Indiana State University, Ann Arbor, Mich.: University Microfilms, 1983. 1 reel
- Zitello, Matthew G., 2002, Facies configuration changes and sediment transport on the Charlestown/Green Hill barrier shoreface. Thesis (M.S.)--University of Rhode Island, Kingston, RI, 149 p.
The EPA's Climate Change Website notes that over the last century the average temperature in Providence, Rhode Island, has increased 3.3°F, and precipitation has increased by up to 20% in many parts of the state. These trends may or may not continue. Over the next century, Rhode Island's climate may change even more. For example, based on projections made by the Intergovernmental Panel on Climate Change and results from the United Kingdom Hadley Centre climate model (HadCM2), by 2100 temperatures in Rhode Island could increase by 4°F (with a range of 1 to 8°F) in winter and spring and by 5°F (with a range of 2 to10°F) in summer and fall. Precipitation is projected to increase by 10% in spring and summer (with a range of 5 to15%), 15% in fall (with a range of 5 to 30%), and 25% in winter (with a range of 10 to 50%). Other climate models may show different results, especially regarding estimated changes in precipitation.
Sea level rise could lead to flooding of low-lying property, loss of coastal wetlands, erosion of beaches, saltwater contamination of drinking water, and decreased longevity of low-lying roads, causeways, and bridges. In addition, sea level rise could increase the vulnerability of coastal areas to storms and associated flooding. Rhode Island beaches have suffered severe damage during hurricanes and storm surges. In general, erosion is most severe at the barrier beaches on the south shore of Rhode Island and bluff areas on Block Island; these areas are likely to erode most if sea level rises. The northern shore of Narragansett Bay, including Cranston, Providence, and Pawtucket, is heavily armored with seawalls and other erosion control devices. At Watch Hill, sea level already is rising by an estimated 10 inches per century, and it is likely to rise another 12.4 inches by 2100. Possible responses to sea level rise include building walls to hold back the sea, allowing the sea to advance and adapting to it, and raising the land (e.g., by replenishing beach sand, elevating houses and infrastructure). Each of these responses will be costly, either in out-of-pocket costs or in lost land and structures.
Rhode Island Sea Grant is another potential source of information on beach erosion.
An interesting little site documenting profile change at East Beach can be found at: http://omp.gso.uri.edu/ompweb/discovery/barrierbeach/bbhistor.htm
A USGS report National Assessment of Shoreline Change: Historical Shoreline Change along the New England and Mid-Atlantic Coasts was released in February 2011. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long-term shoreline change for the New England and Mid-Atlantic coasts was -0.5 meters per year. The average rate of short-term shoreline change for the New England and Mid-Atlantic coasts was also erosional but the rate of erosion decreased in comparison to long-term rates. The net short-term rate as averaged along 17,045 transects was -0.3 meters per year.
General Reference Documents and Websites
The Heinz Center's Evaluation of Erosion Hazards, conducted for the Federal Emergency Management Agency (FEMA), studied the causes of coastal erosion hazards and proposed a variety of national and regional responses. The study, published in April 2000, concentrates on the economic impacts of erosion response policies as well as the cost of erosion itself to homeowners, businesses, and governmental entities.
A NOAA website that has graphs of sea level data for many coastal locations around the country over the last 40 to 50 years and projections into the future is Sea Levels Online.
NOAA Shoreline Website is a comprehensive guide to national shoreline data and terms and is the first site to allow vector shoreline data from NOAA and other federal agencies to be conveniently accessed and compared in one place. Supporting context is also included via frequently asked questions, common uses of shoreline data, shoreline terms, and references. Many NOAA branches and offices have a stake in developing shoreline data, but this is the first-ever NOAA Website to provide access to all NOAA shorelines, plus data from other federal agencies. The site is a culmination of efforts of NOAA and several offices within NOS (including NOAA’s Coastal Services Center, National Geodetic Survey, Office of Coast Survey, Special Projects Office, and Office of Ocean and Coastal Resource Management) and other federal agencies to provide coastal resource managers with accurate and useful shoreline data.
A related site launched in 2008 is NOAA Coastal Services Center's Digital Coast, which can be used to address timely coastal issues, including land use, coastal conservation, hazards, marine spatial planning, and climate change. One of the goals behind the creation of the Digital Coast was to unify groups that might not otherwise work together. This partnership network is building not only a website, but also a strong collaboration of coastal professionals intent on addressing coastal resource management needs. Website content is provided by numerous organizations, but all must meet the site’s quality and applicability standards. More recently, NOAA Coastal Services Center has developed a Sea Level Rise and Coastal Flooding Impacts Viewer as part of its Digital Coast website. Being able to visualize potential impacts from sea level rise is a powerful teaching and planning tool, and the Sea Level Rise Viewer brings this capability to coastal communities. A slider bar is used to show how various levels of sea level rise will impact coastal communities. Completed areas include Mississippi, Alabama, Texas, Florida, and Georgia, with additional coastal counties to be added in the near future. Visuals and the accompanying data and information cover sea level rise inundation, uncertainty, flood frequency, marsh impacts, and socioeconomics.
Erosion Contact Info
Janet Freedman, Coastal Geologist
Rhode Island Coastal Resources Management Council
Phone: (401) 783-3370
Dr. Jon C. Boothroyd
University of Rhode Island
Department of Geological Science
8 Ranger Road, Suite 2
Kingston, RI 02881
See the Erosion Response section
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