Sediment Ridges on the West Florida Inner Continental Shelf: Sand Resources for Beach Nourishment

Abstract

Beach nourishment requires large volumes of sand from offshore and new sources are constantly sought for development. The sediment-starved continental shelf off the central-west coast of Florida has traditionally supplied beach-quality sediments from ebb-tidal shoals and nearshore sand sheets, but as these supplies dwindle, sand searches increasingly look farther offshore for resources. Widely spaced sediment ridges, interspersed by karstified limestone seafloor (hard grounds), offer potential as sand resources that can be exploited by dredging to renourish eroded beaches for shore protection. The sand ridges, late Holocene in age, are generally shoreface detached, sediment starved, and clustered in “ridge fields.” Six sediment ridge fields identified along 285 km of coast (Anclote, Sand Key, Sarasota, Manasota, Captiva, and Collier) contain about 1.4 billion cubic meters of sediments that are potentially available for dredging. Evaluation of these sediment sources, within the purview of the USMinval Code, requires the determination of resources, reserves, and level of certainty of assessment applied to a rating of resource potential. Present research is attempting to identify the overall resource potential with an eye toward eventually determining sand volumes in reserves, which will be much less than the total sand resource volume.