Erosiongreenspun.com : LUSENET : Introductory Geology, Oswego State : One Thread
Do jetties help or hurt beachfronts?
-- Ben Flaiz (firstname.lastname@example.org), April 01, 2001
Jetties tend to do a little of both. Their main function is to keep sand from flowing into a ship channel, which would make the channel increasingly shallow over time (shallow waters cause for ships to run aground). There are often two jetties used, one for each side of the channel. Erosion prevention is another benefit of jetties. Sand that builds up against the jetty can be redistributed along the beach. Jetties also prevent littoral drift and storm waves from entering protected channels. There are drawbacks to jetties, though. Sand starvation and retreat of the shoreline on the downdrift side are possible. These problems are sometimes combated by sand bypass systems pumping sand through a pipeline and behind the downdrift jetty.
Taken from: http://www.bergen.org/
-- Eric Breindel (email@example.com), April 03, 2001.