Houston, J.R., 2023. Measured fate of beach nourishment sand. Journal of Coastal Research, 39(3), 407–417. Charlotte (North Carolina), ISSN 0749-0208.
The fate of sand placed over a 20-year period in one of the largest series of beach nourishment projects ever conducted in the United States is determined by using direct measurements of elevation vs. distance from dunes to closure depth. Four projects placed 11.25 million m3 of sand from 1998–2017 on a 28.8-km-long shoreline at Panama City on Florida's Gulf of Mexico coast. Profile measurements were available in 1996 following Hurricane Opal and in 2018 after Hurricane Michael, one of the largest hurricanes to strike the United States, which came ashore only 30 km from Panama City beaches. The profiles were about 300 m apart within the project template and extended down to closure depth. After about 20 years, 87 ± 3% of the nourishment sand remained on profiles. Some sand used for nourishment was dredged within closure depth along a 3.6-km section and resulted in sand loss of 4% ± 1% as sand partially refilled the dredged holes. About 9% ± 3% was lost to longshore transport out of the project area. Calculations based on the equilibrium profile concept used in U.S. beach nourishment design predicted beaches should have widened 30.9 m ± 0.9 m and profiles raised 0.69 m ± 0.10 m due to the measured volume of sand remaining on profiles from the start of beach nourishment in 1998 to November 2018 after Hurricane Michael. The measured change in beach width was 32.4 m ± 4.0 m, and the rise was 0.66 m ± 0.05 m. The rise of 0.66–0.69 m is comparable to the 0.81 m mean sea-level rise by the year 2100 projected by the Intergovernmental Panel on Climate Change for its worst-case temperature scenario.
