Progress in Management of Sediment Bypassing at Coastal Inlets: Natural Bypassing, Weir Jetties, Jetty Spurs, and Engineering Aids in Design

Abstract

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.