BEACH PROCESSES ON VIEQUES, PUERTO RICO, USA: EFFECTS OF LAS ROMPEOLAS PIER

The northern shore of the island of Vieques, Puerto Rico, is interrupted by the mile-long Rompeolas Pier. Built in the 1940's, the pier creates a large wave shadow and significantly disrupts longshore transport, serving as an excellent case study in beach response to shoreline engineering. Understanding and quantifying both natural processes and anthropogenic effects on tropical island shorelines is increasingly important in light of projected increases in the rate of sea-level rise.

Shoreline position and variation in beach profiles, composition, and grain size are compared along-shore. Results indicate deposition on the up-drift beach and erosion on the down-drift beach, as well as relative fining and coarsening, respectively. Relative abundance of key minerals above and below the pier are used to elucidate transport and source parameters for the beach system. Winnowing of fines from the down-drift beach due to the pier's wave shadow combined with the physical interruption of long-shore transport are responsible for the modern shoreline morphology.