NEARSHORE CIRCULATION AND DREDGED MATERIAL TRANSPORT AT WAIKIKI BEACH

The possibility of using offshore sand deposits as a source of materia l was recently studied as part of a beach nourishment project at Waiki ki Beach, Hawaii, The borrow site is located approximately 1100 meters off the beach. A finite difference model of water circulation and fin e particle transport is used to study dredge-induced far field turbidi ty concentrations. The influence of the dredging pit at the borrow sit e on the stability of the nearshore ocean bottom and on the beach is a nalyzed using the Bailard sediment transport model in the onshore-offs hore direction. Model results show that effects of the dredging operat ion on the beach would be negligible. A maximum sediment accumulation on the ocean bottom of 0.3 kg/m(2) (or equivalently, a 0.2 mm thick la yer) is predicted for one day of operation, which is considered accept able.