Estimating Annual Littoral Drift along the Southeastern Shore of Lake Erie at North East, Pennsylvania, USA

Construction of the Safe Harbor Marina on the southeastern shore of Lake Erie at North East, Pennsylvania, in 19891990 interrupted the previous littoral drift pattern with the predictable starvation of beaches downdrift due to failure in providing the required artificial nourishment. The preconstruction littoral drift volume for the area is unknown. This study aimed to determine the annual sediment volume that would have reached the downdrift beaches if the harbor were not constructed and thereby provide a scientific estimate of the volume of nourishment required there. The rate of sediment being trapped against the updrift side of the harbor was assumed to be the littoral drift rate for this portion of Lake Erie, as both low-level aerial photography through the lake's extremely clear waters and mapping of the nearshore sand distribution indicated that no significant volume of sediment was bypassing the harbor. Repeated highly accurate topographic mapping of the updrift beach and nearshore zone via electronic total station produced surfaces which, when compared via computer, yielded annual transport volumes. October 1993 and June 1994 maps yielded an annual sediment transport volume of 6504-8136 m(3)/year (8507.2-10,641.9 yd(3)/year). Data collected from an earlier (also post-construction) survey of the same area were used to compute the volume change from 1991 to 1994, yielding an average annual littoral drift rate of 7361 m(3)/year (9628.2 yd(3)/year).