Shoreline Dynamics On A High Energy Beach Associated With Relative Sea-Level Fall On The Pacific Coast, Usa

Episodes of localized erosion on the Pacific Ocean beaches of the Makah Tribe, in Washington State, USA, prompted the development and implementation of a shoreline assessment that included repeat beach profile surveys using RTK-DGPS and aerial lidar, and historical change analysis using aerial photos. Analysis of GNSS and aerial lidar suggest patterns of dune toe progradation over the last decade at average rates of ~0.8 m/yr between 2010 and 2022 over almost all the 5.5 km length of beach in Makah Bay, excepting the ~250m long erosional area that prompted the study. A beach vegetation line delineated in aerial photos collected between 1952 and 2019 moved seaward at average rates of ~0.7 m/yr across the entire length of Makah Bay, suggesting that the pattern of progradation is long-lived. We assess evidence to evaluate whether this pattern of dune accretion is related to relative sea-level fall occurring at this site. The Proceedings of the Coastal Sediment 2023.