Duck Nearshore Experiment (SANDYDUCK) 1997

Abstract

Three instrument systems were successfully deployed at Duck NC during the ONR-sponsored SANDYDUCK experiment. A cross shore pressure array and manometer system were used to study wave transformation as waves break across the barred beach, and the resulting setdown and setup on the mean cross-shore water levels. Detailed sand morphology measurements were being made on 5cm to 10m scales using an array of eight acoustic altimeters mounted on the Army Corps of Enginners CRAB vehicle, to extend the large scale morpholgy measurements made by the CRAB each day. These sediment morphology surveys across the 1km cross-shore by 2km longshore study area were made in conjunction with detailed morphology and bottom boundary layer measurements made from an instrumented sled which was moved from beyond the offshore bar to the beach face each day. The sled also measured the vertical structure of the water column to study the mean velocity structure responding to breaking waves, bottom stress, and wind forcing, and the depth of influence of turbulence generated by breaking waves. Bottom stress, dissipation and sediment suspension processes were studied with the Bistatic Coherent Doppler Velocimeter which measured cm scale three component velocity and sediment concentration profiles from the bed to a height of 60cm.