INVESTIGATING THE EFFECT OF WAVE ENERGY ON SEDIMENT CHARACTERISTICS OF VIEQUES, PUERTO RICO USING REAL AND MODELED WAVE DATA

The coast of Vieques, Puerto Rico, is exposed to waves generated both by the trade winds and by tropical storms and hurricanes. Wash-over data from lagoons on Vieques has been used to examine the frequency and intensity of tropical storms over the last 5000 years. Presently, a detailed study of sediment availability, transport and wave heights for the island does not exist and is needed for enhanced understanding and interpretation of previous studies, as well as providing a tool for management in the recently designated public lands at both ends of the island.

Located off the east coast of Puerto Rico between the Caribbean and Atlantic oceans, Vieques formed as part of the Caribbean Island Arc. The island’s diverse geology includes volcanic and plutonic igneous rocks, sand-rich marine limestones, and unconsolidated alluvial sediments. This tropical/desert island is dominated by pocket beaches and mangrove swamps on the southern shore, and moderately-connected beaches along the northern shore. Sedimentary material in this sand-starved system is delivered to the coasts from both the upland and from coral reefs offshore.

The SWAN (a 3rd generation wave model) is utilized to numerically simulate average and extreme wave climates in the near shore environment of Vieques, Puerto Rico based on long-term data from ocean buoys. Both modeled and observed real-time wave data are used to investigate the effects of wave energy on the coastline via comparison with variations in beach morphology, grain size, and sediment composition, with specific attention to coastal geomorphology surrounding Las Rompeolas, a mile-long pier interrupting sediment transport along the north shore of Vieques.