BEDFORM DYNAMICS IN MORICHES INLET, LONG ISLAND, NEW YORK
In sandy inlets sand waves and megaripples are common and their migration can be a proxy for bedload. Because acoustic bathymetric measurements are highly accurate and do not interfere with the currents, this method can be applied more easily and over a larger area than direct measurements of sediment transport. Bedform migration is a meso-scale sediment transport process and needs to be quantified in order to link micro-scale processes explaining the movement of individual sand grains and the larger macro-scale processes that shape our shorelines.
Thirteen single-beam acoustic bathymetric surveys were collected during a 3-day period at Moriches Inlet, Long Island New York. The surveys were collected as little as 1-hour apart and therefore can be used to describe the detailed movement of the bedforms within a single tidal cycle. In addition, side scan, sediment data, and current data were gathered to describe the geometry and setting of the bedforms. The bedforms are ~0.3-0.6 m high with a spacing of ~15 m. Preliminary data show that some of the most prominent bedforms migrate up to 0.5 m/hr. The tidal currents are symmetrical with ebb and flood currents reaching 45 cm/sec.