Principal component analysis of morphology change at a tidal inlet: Shinnecock Inlet, New York

Principal component analysis was used to identify dominant patterns of change in morphology of five recent LIDAR surveys of Shinnecock Inlet. The first principal component accounted for 55% of the ebb shoal variability over a period of 6 years (21 June 1994 through 3 July 2000) and identified three accretionary features: (1) an updrift bar complex, (2) a downdrift bypass bar, and (3) shore perpendicular bars along the downdrift barrier. The evolution of these features, accounted for in the first principal component, appears to be the result of both a natural deflection of the main ebb channel and realignment of the channel by dredging. Evidence of channel migration is seen in comparison of 14 sequential historical photographs of the inlet from 24 September 1938 to 22 April 1997. This study also documents that sand waves (length = 100 to 200 m) within the outer channel region were displaced because of variations in incident wave climate.