RESULTS OF INLET FORMATION AT NEW INLET, OUTER CAPE COD, MA

New Inlet, located along outer Cape Cod, formed during a Northeast storm (2 January, 1987) separating South Beach from Nauset Spit. In the months following the breach, New Inlet grew to nearly 2km in width, effectively capturing the tidal prism of Pleasant Bay from Chatham Inlet. Enlargement of the inlet and erosion of the adjacent barriers provided sediment for growth of the flood tidal delta, formation of subtidal shoals, and construction of a spit attaching South Beach to the mainland. The breach also substantially changed the tidal hydraulics of the backbarrier causing the development of mutually evasive tidal channels. Subsequent evolution of the inlet involved development of a spit platform, growth of the ebb-tidal delta, and a southerly deflection of the main ebb channel. The spit platform built 1 km to the south from Nauset Spit and was incised by a number of shallow channels. During this period the ebb-tidal delta grew from sand intercepted from the longshore transport system resulting in downdrift shoreline retreat and an overall thinning of South Beach barrier. Extension of the spit platform and enlargement of the ebb-tidal delta caused a southerly deflection of the main inlet channel, such that it impinged upon the northern end of South Beach. The circuitous path of the main channel produced an inefficient exchange of water between the backbarrier and the ocean, causing increased flow through one of the shallow secondary channels across the spit platform. Deepening of this new channel created a shorter and more efficient pathway for water to exit the inlet. Inlet sediment bypassing has been re-established and South Island is being nourished with sand derived from onshore bar migrations.