Shoal-Reduction Strategies for Entrance Channels: Fid-Bau Portal

Shoal-Reduction Strategies for Entrance Channels

J. D. Rosati / N. C. Kraus

Purpose: This Coast Engineering Technical Note (CETN) presents several methods for reducting sediment in navigation channels at coastal inlets and entrances. Background: From fiscal year (FY) 1995 through 1998, the US Army Corps of Engineers (USACE) dredged between 200 and 300 million m3/yr from Federal channels. Maintenance dredging accounted for an average of 89 percent of this volume, and new work and emergency dredging comprised the remainder. Total dredging expenditures increased from approximately $532 to $713 million in FY 1995 through FY 1998, with maintenance dredging accounting for 78 percent of the cost. A reduction in maintenance dredging can represent a significant cost and timesaving measure to the operation and maintenance of USACE waterways. The focus of this CETN is how sediment shoals into open-coast channels. The primary sediment-transport pathways can be referenced to the jetties stabilizing the inlet entrance. Sediment can move around the tip of a jetty, entering directly into the channel; around the tip of the jetty, on to the ebb shoal and into the portion of the channel that transverses the ebb shoal, through a jetty, over a jetty, and around the landward side (see green arrows in Figure 1). Pope (1997) gives a classification system of channel shoaling based on general considerations of geomorphology.