PLANNING, PRELIMINARY DESIGN, AND INITIAL PERFORMANCE OF THE NAGS HEAD BEACH NOURISHMENT PROJECT

Abstract

A 3.5 million cubic meter beach nourishment project was completed along 16 kilometers of shoreline at Nags Head, North Carolina, 32 kilometers south of the US Army Corps of Engineers Field Research Facility at Duck. The project is the largest locally-funded nourishment accomplished to date in the United States. Three ocean-certified hopper dredges and one cutterhead suction dredge constructed the project between May and October 2011. This paper discusses the planning, design, and initial performance of the project. Nags Head is exposed to high waves from the northeast which generate net southerly transport over the long term. A key design issue for the project was the large gradient in erosion rates from north to south. Fill sections were varied accordingly based on documented volume erosion rates and model simulations for the area. Permitting involved over five years of environ¬mental reviews because of the need to work during fair-weather summer months in the relatively high-energy setting. The design also built on prior work in connection with a federal nourishment project scheduled for the area if and when funds become available. Two offshore areas strategically located close to south Nags Head were utilized for construction which proceeded efficiently under summer waves until late August when Hurricane Irene impacted the area. The hurricane and fall northeast storms produced rapid adjustment of the construction profile but no net loss of sand from the project area. Post-project surveys show initial profile equilibration was largely confined to the inshore zone inside the 3.7 meter (m) [âˆ'12 foot (ft) NAVD] contour. Depth of closure at decadal scales is estimated to be âˆ'7.3 m (âˆ'24 ft NAVD).