Bypassing Sand at Coastal Inlets

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Bypassing Sand at Coastal Inlets

Serial Information: Civil Engineering—ASCE, 1978, Vol. 48, Issue 3, Pg. 57-60

Document Type: Feature article

Abstract:

To reduce dredging requirements and to provide calm navigation channels, the U.S. Corps of Engineers often constructs jetties and breakwaters. These structures block sand drifting along the shoreline, so beaches downstream can disappear when eroded sand is not replaced. To remedy this problem, the Corps has used weir jetties and eductor bypass systems. A weir jetty or weir breakwater has a depressed section on it to allow sand to wash over it into an impoundment basin. The basin is then emptied, and the sand is pumped to nourish downstream beaches. One system for excavating sand is the eductor system, which uses water circulating through a submerged nozzle to create a suction; a shore-mounted pump discharges the sand downstream. The Corps is developing design guidelines for weir jetties; has fixed-bed physical models to design them; and has conducted field demonstrations of weir jetties and the eductor system.

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