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News Release December 10, 2001
GSA Release No. 01-66
Contact: Ann Cairns
Director – Communications and Marketing, 303-357-1056

Lowering Rates of Beach Erosion:
Estuaries may be Key

The tide rolls in and the tide rolls out. Many geologists believe that the interaction between the tides and water moving down rivers causes sand to settle into estuaries that act as "sinks." That is, the sand cannot move out of them. In the December issue of the GEOLOGICAL SOCIETY OF AMERICA BULLETIN, Michael Fenster from Randolph-Macon College proves this notion is all washed up.

He and his colleagues conducted research at the Kennebec River estuary in northeast Maine to test their hypothesis that spring floods supplant tidal energy and deliver sediment to the coast.

"We found that spring floods that are caused mostly by rain and melting snow provide enough energy to change the overall net direction of sand migration downstream," Fenster said. "Our work shows that policies that regulate whether or not to build dams and where to dump dredged materials should consider the net movement of sand within estuaries. This change could result in lower erosion rates on beaches."

This research establishes that estuaries contribute coarse-grained sediment to the coast in some places such as New England, that dams are a crucial component of the coastal system because they can cut off the supply of sediment that would ordinarily and naturally be transported to the coast, and that coarse sediment that fills estuaries and harbors--consequently producing navigation problems--do not always come from the ocean.

"Beaches can receive new nourishment from rivers," Fenster said. "What we can see on the beach is not the sum total of what we have."

— by Kara LeBeau, GSA Staff Writer

Contact information:
Michael Fenster
Randolph-Macon College
Environmental Studies Program
Ashland, VA 23005
PHONE: 804-752-3745

To read the abstract of this article, go to:

To obtain a complimentary copy of this or any other GSA BULLETIN article, contact Ann Cairns, Geological Society of America.


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