Myrtle Beach (2001-2010)—Another Decade of Beach Monitoring Surveys after the 1997 Federal Shore-Protection Project

Situated in the center of a 25-mile (40-km) arcuate shoreline between Little River Inlet and Murrells Inlet, Myrtle Beach, South Carolina, is the heart of a booming tourist area. However, Myrtle Beach suffered beach degradation in the 1980s. As recently as 1985, much of Myrtle Beach was armored by seawalls and there was little or no high-tide beach. Myrtle Beach was also found to have lost sand between the 1950s and 1980s at rates of 0.5–2.5 cubic yards per foot per year (cy/ft/yr) (1–6 m3/m/yr). Despite the poor natural condition of the beach and constant loss of sand year after year, Myrtle Beach has become one of the best beaches in the United States due to the nourishment efforts by the City of Myrtle Beach (1986–1989) and the federal government (1997 and 2008). The federal nourishment project was constructed by hydraulic dredge in 1997 using an offshore deposit. Approximately 2.2 million cubic yards (1.7 million cubic meters — m3) were placed along the 9.23-mile-long (14.85 kilometers) shoreline of Myrtle Beach. The average fill density was ~45 cy/ft (113 m3/m). Annual surveys have been performed by the authors since 2001 using a network of 70 profile lines, most of which extend beyond 15-ft (4.6-m) depths (the estimated Depth of Closure) in this setting. In 2008, as planned by the federal government, an additional 1.5 million cubic yards (1.15 million cubic meters) were added to Myrtle Beach, further advancing the shoreline. The average fill density of the 2008 project was ~33 cy/ft (83 m3/m). Survey results show that the net gain between January 1997 and May 2010 represents 83 percent of the nourishment volume placed. Therefore, nourishment losses have been moderate, totaling ~17 percent of the federal fill. The average annual loss rate since 1997 has been ~1.15 cy/ft/yr (2.9 m3/m/yr), which is below the loss rate for the 1986–1989 project (measured within the visible beach to low-tide wading depth). The lower rate partly reflects an incrementally coarser sediment placed in 1997 (~0.3 mm versus ~0.25 mm mean grain size) and no major storms.