LONGSHORE VARIATION OF GRAIN SIZE DISTRIBUTION ON THE SOUTHERN COAST OF LONG ISLAND, NEW YORK: TEST OF A SEDIMENT TRANSPORT MODEL

Portions of the south shore of Long Island are eroding at an accelerating rate, which is a matter of concern for residents and industry. Twenty-two samples from Long Island south shore’s nearshore environment were collected and analyzed for grain size trends in order to assess the utility of the sediment transport model created my McLaren and Bowles (1985). The model assumes unidirectional transport, single source sediment derivation, and that net longshore sediment transport accounts for sediment textural trends. It suggests that two trends in grain size, sorting, and skewness reveal the direction of transport. The data from this study used to test McLaren and Bowles (1985) model predict a primary sediment transport direction that does not match the known direction of longshore currents along the coast. The discrepancy between the observed transport direction of the longshore current on Long Island’s south shore and that predicted by the McLaren and Bowles (1985) model reduces the usefulness of the model for understanding sediment movement in the nearshore barrier beach environment.