Science Seminar Series

Tuesday, October 1st, 2019, 1:00 PM

Miya Pavlock McAuliffe

Moss Landing Marine Labs

“Video observations of shoreline and sandbar at a wave dominated barred beach: northern Monterey Bay, California”

Abstract: This contribution presents results from a study of shoreline and sandbar evolution over nearly two years at Sunset State Beach, a sandy barred beach in the northern Monterey Bay of Central California. Shoreline and sandbar positions were extracted from rectified time exposure image mosaics derived from a dual camera Argus station. This micro-mesotidal sandy beach shows a strong seasonal signal and evidence of wave driven shoreline erosion and recovery within the 600m alongshore study area. The relatively calm winter of 2017-2018 corresponded with rapid shoreline erosion in early January after a peak in wave energy, followed by gradual accretion and stability with lower energy conditions. The relatively high energy winter of 2018-2019 resulted in rapid erosion followed by delayed accretion, with a larger range in shoreline position than the previous year. The sandbar followed expected seasonal trends, migrating seaward in the winter and landward in the summer. However, the sandbar appears to be more sensitive to small changes in wave conditions and possibly buffers the shoreline from smaller wave events. Sunset State Beach exhibits an equilibrium shoreline response: the shoreline erodes further landward under higher energy conditions and accretes further seaward during lower energy conditions. This study provides further understanding of the relationships between waves, shoreline, and sandbar using an automated data collection system yielding a dataset with temporal resolution difficult to obtain using traditional survey methods. 

Natural Bridges State Beach, shown here in the middle of the photo, is nestled amongst coastal neighborhoods in the far western end of Santa Cruz, California. View is looking south. The offices of the USGS Pacific Coastal and Marine Science Center are just a few hundred feet north, outside the bottom portion of the photograph.

Photo by Laura Torresan