The effect of shore armoring on beach slope in mixed sand-and-gravel beaches

Abstract

[author abstract] This study is a comparison of beach orientation, fetch length, and seawall toe height for 31 pairs of armored/unarmored, mixed sand-and-gravel beaches in southern Puget Sound. Beach profiles from top of berm or toe of armoring to MLW were standardized using NOAA-verified tide tables as a datum for all profiles. Changes in beach profile within each pair were used to evaluate armoring effects. Presumed changes due to armoring were not attributable to a single factor, but there were consistent trends. Fetch length and direction for both prevailing winds and predominant winds were compared. Fetch length, and the angle of the prevailing wind to the beach were compared singly and in groups, but no correlation was found. Comparisons of profiles taken both in spring and in late summer on a small number of beach pairs indicate opposite seasonal trends.