Assessment of the Hydraulics and Longevity of Wood End Cut (Inlet), Cape Cod, Massachusetts, USA

Gail M. Ashley

Abstract


The terminus of Cape Cod, Massachusetts, consists of a recurved barrier spit. Wood End Long Point, which protects an extensive salt marsh-tidal flat (2.5 km2 ). A 1.875-m permeable stone-dike connects the dune-covered barrier with high land of the Cape, completing the enclosure of the tidal flat. The barrier was breached during an unusually high springtide (4 m) by a 1-m storm surge during the Blizzard of '78 (Feb. 7) and has remained open by natural processes. A physical process study utilizing velocity, discharge, tidal stage, hydraulic head, vibra-core and dye circulation data was carried out to: (1) determine the effect of the dike on inlet processes, (2) Quantify sediment transport through the inlet and (3) estimate longevitv of the inlet. Water floods onto the tidal flats through the inlet (42%) and the dike(58%), and ebbs through inlet (21 %) and dike (79%) creating a residual current drift entering the inlet and exiting the dike. There is net landward movement of sediment through the inlet. The back-barrier tidal flat is a sediment sink. A coarse sand and gravel flood tidal delta (area=90,000 m2 ; vol. =75,000 m3) has accumulated on the tidal flats during the 7 1/2 year period following the breach.


Keywords


Inlet; hydraulics; sedimentation; flood tidal delta; dike; tidal flat; vibra-core; tidal prism; velocity; bedforms

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