ABSTRACT

The southwest shoreline of Honeymoon Island, an arcuate barrier feature, was extended seaward by a dredge-fill operation in 1969. During the project, 1.5 million yards of material composed predominately of boulder size limestone was dredged from 1500 feet offshore to bring the southwest beach to an elevation of five feet above mean sea level.

A series of aerial photographs taken between 1967 and 1971 indicate cyclic patterns of erosion and deposition prior to and following the dredge-fill operation. Significant alterations evident in the photographs include marked erosion of the southwest shoreline of the island, and the deposition of a series of curved spits or "hooks" along the northwest shoreline.

Erosion of the southwest shoreline by southeasterly longshore littoral drift is substantiated by the following data collected during a six month period: (1) current measurements taken around the island; (2) grain size and roundness studies of sediment samples collected monthly from ten sampling locations; and (3) monthly field observations and measurements of shoreline configuration and sediment composition of the foreshore. Formation of the hooks is related to flood tide currents and storms.

Data indicate that the dredge-fill operation enhanced erosion of the southwest shoreline and that continued erosion in that area can be anticipated. The methodology of this study could be utilized in evaluating the potential effects of similar dredge-fill projects.