Nicholas C. Kraus, Hans Hanson, Sten H. Blomgren


Coastal zone management policy in the United States and many other countries discourages use of groins for shore protection, even though properly designed groins can maintain beach width, increase longevity of beach fills, and prevent loss of sand into inlets, navigation channels, and submarine canyons. A lack of a systematic approach to groin functional design and a poor image from incorrect applications are probably responsible for the aversion to groins. In this study, a modern approach to groin functional design is demonstrated by applying the shoreline response model GENESIS to simulate the action of single and multiple groins. Groin bypassing and permeability, evolution of the shoreline in a groin field, and groin tapering are discussed. The balance between net and gross sand longshore transport rates emerges as an important factor controlling groin functioning. A criterion is introduced for judging groin success, and an example design diagram is developed based on this criterion to demonstrate the feasibility of developing a general and rational functional design procedure. Predictions are tested in reproducing shoreline change observed at the 15 groins at Westhampton, Long Island, New York.


groin; groin system; groin design

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