PROGRESS IN MANAGEMENT OF SEDIMENT BYPASSING AT COASTAL INLETS: NATURAL BYPASSING, WEIR JETTIES, JETTY SPURS, AND ENGINEERING AIDS IN DESIGN

Seabergh-Kraus-CEJ-03
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Coastal and Hydraulics Laboratory, 3909 Halls Ferry Road,

Vicksburg, MS 39180 USA

∗

William.C.Seabergh@erdc.usace.army.mil

†

Nicholas.C.Kraus@erdc.usace.army.mil

Received 29 September 2003

Revised 6 October 2003

Maintenance of navigable channels at coastal inlets typically requires sediment bypassing

to preserve integrity of the adjacent beaches. Artificial bypassing mimics or preserves the

pathways of sediment in the littoral zone and harmonizes the requirement for deepening

navigation channels within the context of the natural sediment-sharing system of inlets

and beaches. A range of techniques can be applied to perform bypassing. Customary

on-demand channel dredging is not always the best solution because sediment shoaling

does not necessarily follow a predictable schedule, potentially compromising navigation

reliability between allowable dredging windows. If sediment can be directed to a location

other than the channel, planning of dredge operations may be optimized and less expensive

equipment feasible. A weir jetty system is one such solution. This paper presents progress

in understanding of sediment bypassing through analytical prediction and takes a lessons-

learned approach to design and modification of weir jetty bypassing systems. Results from

recent physical model studies of spur jetties are also discussed with regard to their control

on the nearshore current at coastal inlets and how spurs can be designed to alter sediment

bypassing.

Keywords : Coastal inlets; sand bypassing; weir jetty; jetty spur.

1. Introduction

Coastal inlets provide a channel for transportation from sea to harbor ports and

allow water exchange and renewal necessary for the ecological health of bays and

estuaries. In sandy coastal regions, a navigation channel has a tendency to be a

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