The Relationship between Beach Grain Size and Intertidal Beach Face Slope

McFall, B.C., 2019. The relationship between beach grain size and intertidal beach face slope. Journal of Coastal Research, 35(5), 1080–1086. Coconut Creek (Florida), ISSN 0749-0208.The relationship between beach grain size and beach face slope is investigated with data from 181 sand beaches around the world. The analysis confirms previously identified trends of increasing beach face slope with increasing sediment grain size and decreasing beach exposure to wave energy. The present work extends previous studies by using a repeatable method to classify the beach exposure to wave energy and derives equations for the beach face slope based on sediment grain size and beach exposure. The derived equations match the measured beach face slope with r2 correlation coefficients of 0.87, 0.88, and 0.87 for protected, moderately protected, and exposed beaches, respectively. The derived equations allow for a rapid estimate of the beach face slope based on the sediment grain size for a range of beach exposures.