Nearshore Disposal: Onshore Sediment Transport,
COASTAL ENGINEERING RESEARCH CENTER FORT BELVOIR VA
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New dredge-disposal techniques may serve the dual role of aiding 1 sand bypassing across coastal inlets, and 2 beach nourishment provided that dredged sediments placed seaward of the surf zone move shoreward into that zone. During the summer of 1976, 26,750 m of relatively coarse sediment was dredged from New River Inlet, N.C., moved downcoast using a split hull barge, and placed in a 215 m coastal reach between the 2 m and 4 m depth contours. Bathymetric changes on the disposal piles and in the adjacent beach-nearshore area were studied for a thirteen week period to determine the modification of the surrounding beach-nearshore profile and the net transport direction of the disposal sediment. Final surveys showed accretion at the base of the foreshore, complete filling of the trough, a platform or new trough at the initial surf-zone bar position, disappearance of the surf-zone bar, and generally a more seaward surf zone boundary. Profiles adjacent to the disposal area showed slight accretion seaward of the surf zone. The predominant transport direction of disposal sediment is interpreted to have been shoreward into the surf zone in the direction of the coarsest native sand and then in the direction of the longshore current. The increased width of the platform-disposal bar complex may provide benefits by increasing the amount of wave energy dissipation in the surf zone and hence, less erosion of the beach.
- Physical and Dynamic Oceanography
- Civil Engineering