Planning and design of low-weir section jetty at Masonboro inlet, North Carolina

Abstract

A berm and dune project for shore and hurricane protection was recently completed at Wrightsville Beach, North Carolina. A navigation project provides for a channel 14 feet deep and 400 feet wide through Hasonboro Inlet which forms the southern boundary of Wrightsville Beach. It has been found infeasible to maintain the channel by dredging alone. Ivork has been started on a 3,400-foot-long jetty on the north shore of Masonboro Inlet. The shoreward 1,700 feet will be constructed of concrete sheet-piling and the contract calls for a rubble-mound structure for the oceanward 1,700 feet. The concrete sheet-piling section of the project will include a 1,000-foot weir section with an elevation of 2 feet above mean low water, which is about midtide. A deposition basin will be provided between the jetty and the navigation channel. The paper will discuss erosion rates at Wrightsville Beach since the 1930's; shoaling in the navigation channel, describe briefly the berm and dune project at Wrightsville Beach and describe in some detail the jetty under construction, including the factors that led to the selection of a "low-weir" structure. Some of the elements that entered in the structural design will be mentioned, but complete design data will not be included since common procedures were followed and no unusual design problems were encountered.