Beach Changes Caused by the Atlantic Coast Storm of 17 December 1970.
A low-pressure system with 20- to 35-knot winds caused waves up to 11 feet high and tides up to 3.6 feet above normal along Atlantic coast beaches, North Carolina to New England, from 16 to 18 December 1970. Ninety-one beach profile lines were surveyed from dune to low tide terrace within 2 weeks be...
Main Authors: | , , |
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Format: | Text |
Language: | English |
Published: |
1977
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Online Access: | http://www.dtic.mil/docs/citations/ADA037378 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA037378 |
Summary: | A low-pressure system with 20- to 35-knot winds caused waves up to 11 feet high and tides up to 3.6 feet above normal along Atlantic coast beaches, North Carolina to New England, from 16 to 18 December 1970. Ninety-one beach profile lines were surveyed from dune to low tide terrace within 2 weeks before the storm and immediately after the storm; sand levels at pipes along selected profile lines were measured during the storm. Comparison of before-and-after surveys indicates that 80 percent of the profile lines showed a net loss of sand above mean sea level (MSL). Profiles to wading depth showed accretion below MSL in most cases. The profile line exhibiting maximum erosion (21.7 cubic yards per foot) occurrence at Cape Cod, Massachusetts; maximum accretion (24.4 cubic yards per foot) was found at Atlantic City, New Jersey. Maximum vertical changes in sand level (4 to 5 feet) were observed on coarser, steeper beaches (Cape Cod and Westhampton Beach, New York), and maximum horizontal changes in the position of the MSL contour (-96.3 feet) were observed on finer, flatter beached (Ludlam Island, New Jersey). Extrapolation from surveyed profiles indicated that a minimum of 10.1 million cubic yards of sand was moved from the beach above MSL along 450 miles of ocean front between Cape May, New Jersey, and Race Point, Massachusetts, by this storm. The intensity of the storm is estimated to be equaled or exceeded twice a year. (Author) |
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