Inlet Formation and Evolution of the Sediment Bypassing System: New Inlet, Cape Cod, Massachusetts

Abstract

ABSTRACT Nauset Spit was breached during a moderate northeast storm on 2 January 1987, forming New Inlet. Factors leading to the breach included a long-term narrowing of the barrier; a 0.5-m storm surge superimposed on near perigean, perihelion, and spring tide conditions; restricted flow through existing inlets, and large differences in tidal range and tidal phase between the ocean and Pleasant Bay. Ultimately, destruction of the foredune ridge and a large hydraulic slope across the barrier (> 1.2 m) facilitated the development of an overwash channel, which led to tidal exchange and inlet formation. As the channel captured an increasingly larger portion of the bay tidal prism, the inlet grew in size from 0.5 km after two months to almost 2.0 km wide by early 1988. Opening of New Inlet increased the tidal range from 1.2 to 1.5 m, which drastically changed the hydraulic character and sediment transport patterns in Pleasant Bay. The opening of New Inlet washed much of the sand from the eroding barrier into ...