Jetty spurs at coastal inlets for reduction of navigation channel shoaling

The Coastal and Hydraulics Engineering Technical Note (CHETN) herein provides information on the effect of a jetty spur on the beachside circulation near a coastal inlet jetty and discusses introductory design considerations relating to alteration of water and sediment circulation near the beach side of jetties. Examples are presented from field and laboratory studies. A jetty spur may be defined as a short structure added to a jetty that flanks a navigation channel through an inlet. The spur will typically be nearly perpendicular to the jetty, but may be oriented at some angle with respect to the jetty in the range of 45 to 90 degrees. The spur may be added on the beach side of a jetty to prevent sediment from entering the inlet or may be placed on the channel side to divert the tidal current away from the jetty to reduce scour and possible jetty instability. This CHETN examines the design and performance of jetty spurs at Bakers Haulover Inlet, Florida, Fort Pierce Inlet, Florida, Siuslaw River Inlet, Oregon, Shark River, New Jersey, and Gray's Harbor, Washington. The report also includes results from a pilot study of spurs that was conducted at the Coastal Inlet Research Program's physical inlet model. The physical model facility is a large experimental basin (46 meters wide by 99 meters long) with an idealized inlet and smooth offshore contours. Short-period waves and tidal currents can be simulated in this facility. (1 table, 13 figures, 7 refs.)