LITTORAL TRANSPORT IN THE GREAT LAKES

L. Bajorunas

Abstract


The Great Lakes Superior, Michigan, Huron, Erie, and Ontario extend almost to the middle of the North American Continent. With their 95,000 square miles of water surface and their three navigable connections with the Atlantic Ocean and Gulf of Mexico, they affect the well-being of about 4.0 million people living within their vicinity in Canada and the United States. Possessing a shoreline of 6,600 miles, these waters have been called the fourth coast of the continent along with the Atlantic, Gulf, and Pacific coasts. This paper analyzes one of the many problems of the Great Lakes, the littoral transport problem.
Littoral transport has been defined as the movement of material along the shore in the littoral zone by waves and currents. The material thus transported is referred to as the littoral drift. The littoral drift originates from the beach material, being picked up by the water and transported along the shore and deposited in another location. Shore erosion, littoral transport, and deposition of drift are all factors in the littoral process.
A knowledge of the littoral process is important for many engineering projects including the construction and maintenance of shoreline harbors. The harbor breakwater extending from the shore into deep water forms a littoral barrier, and by stopping the transport action causes the depositio of drift on the updrift side. If the breakwater does not entirely stop the transport, or when the storage area on the updrift side is filled, the drift will bypass the breakwater and fill the dredged navigation channel causing frequent and expensive maintenance dredging. This problem is especially important in the small harbors on the Great Lakes planned every 25 to 30 miles as refuge for fishing and pleasure boats. These harbors have a rather small capacity for littoral drift, and the costs of maintenan dredging of so many entrance channels would be almost prohibitive.
In order to provide data required for the design and economic evaluation of the small refuge harbors on the Great .Lakes, the United States Lake Survey, Corps of Engineers, conducted a study of the best method of estimating the rate of littoral transport along the shores of the Great Lakes. Although much of the data used in this paper was taken from the above study, the views and

Keywords


Great Lakes; littoral transport; shore erosion

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