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Shoreline, grain-size, and sediment total-carbon changes were monitored, on a monthly basis, on three Galveston Island beaches, from January through December 1983. The study area included: (1) East Beach, obstructed by groins and a seawall; (2) Galveston Island State Park, obstructed by fences artificially stabilizing the dunes; and (3) West Beach, an unobstructed beach.
Beach profiles revealed the effects of beach obstruction, such as erosion and undercutting at East Beach, and truncation of the dunes at Galveston Island State Park. Approximately 20 m of expansional cutback occurred on the beaches after Hurricane Alicia hit on August 18, 1983.
Contour maps of grain-size and total-carbon distributions reflect the movement of beach sand by either onshore-offshore transport during low-energy periods, or longshore, edge-wave transport during high-energy periods.
Statistical analyses revealed a small variation in grain size throughout the year. There were well-defined times of either no correlation or strong correlation between total carbon vs. mean grain size, skewness vs. mean grain size, kurtosis vs. mean grain size, total carbon vs. percent sand, total carbon vs. skewness, and skewness vs. kurtosis. Strong correlation was found in response to high-energy events, whereas no correlation was found in response to low-energy events.
Galveston Island is undergoing net erosion and appears to be in a metastable state, still capable of responding to oceanographic conditions. The economic effects of Hurricane Alicia include considerable loss of the shoreline and destruction of property. Beach nourishment appears to be the only economically feasible solution to counteract the extensive erosion.
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