E N G I N E E R I N G
C H A L L E N G E :
H A N D O U T
A
Groyne
Beach material builds up along a groyne as the current pushes it downdrift. This makes for wider beach areas and better protection against erosion as more sand is available to absorb the wave energy. The environmental impact of groynes is complicated. There is a corresponding loss of beach material on the updrift side, requiring that another groyne be built in that location. This typically leads to more and more groynes being installed along vast stretches of coastline. Groynes are among the most cost-effective measures taken to prevent coastal erosion since they require very little maintenance and can last for 10 – 20 years. With an average cost of $18 million per kilometer, it is no surprise that groynes are the most widely used method of erosion prevention. While effective against sandy beach erosion, groynes do not protect the beach against storm-driven waves. If placed too close together, groynes will create currents, which will carry more sand material offshore. Many communities have opposed the use of groynes because they tend to cause more problems to neighboring beaches and are drastically change the natural look of the areas where they are installed.
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8th Grade Integrated 89
Engineering Challenges
Groynes are barriers or walls installed perpendicular to the sea. They are often made of concrete, rock or wood. Groynes are typically used in areas with a prevailing current flows at an angle to the shore, which causes beach material to drift in once direction.