Short-Term Interactions Between Hydraulics and Morphodynamics of a Small Tidal Inlet, Long Island, New York

Abstract

The hydraulic processes and morphodynamics of a small established tidal inlet were observed in order to determine the most important factors controlling hydraulic and morphological evolution as well as effects of the inlet on adjacent beaches. Inlet morphology and hydraulics evolved largely in response to wave-induced sand transport, which gradually overwhelmed tidal flushing and filled the inlet by the end of the eight-day study. Cross-sectional area of the inlet decreased due to shoal-building as waves transported sand into the inlet. Inlet currents underwent a transition from initial ebb dominance to flood dominance in response to reductions in inlet throat cross-section and associated frictional effects. Inlet currents produced a tidal signature in nearby longshore currents. The inlet measurably affected the stability of adjacent beaches, producing updrift accretion and downdrift erosion while the inlet was open.