Mechanisms Of Sand Loss From An Estuarine Groin System Following An Artificial Sand Fill

Following the placement of 410,590 cu m of sand fill in a groin system at Willoughby Spit, Virginia, in August and September, 1984, the volume of fill retained in a test compartment was observed to decrease slowly with time as a result of sediment movement in two shorewise zones (1) nearshore and dominated by wave and swash action and (2) beyond the groin ends and dominated by action of strongly asymmetrical tidal currents. Results show that the intensity of sediment transport decreases with elapsed time after the fill as conditions of static equilibrium are slowly approached. An equation for post-fill shoreline history was developed based on this fall-off in sediment transport intensity and was constructed so as to include the main mechanisms of sand loss. Predictions of fill loss based on these data lead to recommendations for modification of the groin system. Grant no. R/CP-1