Streaming Media
Presentation Abstract
In May 2018, The Washington State Department of Ecology Coastal Monitoring & Analysis Program (CMAP) performed a coastal topographic and bathymetric survey along a 4-km reach of west Whidbey Island between West Beach County Park and Hastie Lake County Park with topographic lidar extending southward an additional 5 km to Point Partridge at Fort Ebey State Park. High-resolution topographic and bathymetric data were collected using boat-based lidar and dual-head multibeam sonars aboard the R/V George Davidson, with additional topographic data collected by foot using GNSS on backpacks to fill in shadows from the lidar and obtain intertidal cross-shore beach profiles. By employing these methods, seamless coastal zone mapping from the bluff top to over 10-m water depth was achieved at a 0.5-m grid resolution. The topographic survey revealed a steep feeder bluff with compound slopes, active erosion, and landslides and a mixed-sediment beach substrate with varying distributions of sand, gravel, and cobble. The bathymetric survey showed a relatively uniform sandy shoreface at each end of the reach that bounds more complex bathymetry in between, including irregular deposits of large boulders, cobble bars, and intertidal embayments. Much of the nearshore appeared to have relative abundance and diversity of submerged aquatic vegetation, dominated by surf grass and kelp. This topo-bathymetric survey enables the assessment of how sediments supplied by bluff erosion are dispersed along the beach and throughout the nearshore zone to influence habitats. The U.S. Geological Survey are using these data to validate process-based models, including wave runup that drives erosion of the bluff toe and mixed-grain nearshore sediment transport. Such models are critical for predicting beach and bluff morphology change, the long-term coastal response to sea-level rise, and their associated effects on property, infrastructure, and habitats.
Session Title
Poster Session 1: Applied Research & Climate Change
Conference Track
SSE14: Posters
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-posters-408
Start Date
26-4-2022 4:00 PM
End Date
26-4-2022 4:30 PM
Type of Presentation
Poster
Genre/Form
conference proceedings; presentations (communicative events); posters
Subjects – Topical (LCSH)
Marine sediments--Quality--Washington (State)--Whidbey Island; Coastal sediments--Washington (State)--Whidbey Island; Marine habitats--Washington (State)--Whidbey Island; Coastal mapping--Washington (State)--Whidbey Island
Geographic Coverage
Whidbey Island (Wash.)
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Format
application/pdf
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons
West Whidbey Island nearshore bathymetry and coastal topography survey reveals diversity of sediment, morphology, and habitat
In May 2018, The Washington State Department of Ecology Coastal Monitoring & Analysis Program (CMAP) performed a coastal topographic and bathymetric survey along a 4-km reach of west Whidbey Island between West Beach County Park and Hastie Lake County Park with topographic lidar extending southward an additional 5 km to Point Partridge at Fort Ebey State Park. High-resolution topographic and bathymetric data were collected using boat-based lidar and dual-head multibeam sonars aboard the R/V George Davidson, with additional topographic data collected by foot using GNSS on backpacks to fill in shadows from the lidar and obtain intertidal cross-shore beach profiles. By employing these methods, seamless coastal zone mapping from the bluff top to over 10-m water depth was achieved at a 0.5-m grid resolution. The topographic survey revealed a steep feeder bluff with compound slopes, active erosion, and landslides and a mixed-sediment beach substrate with varying distributions of sand, gravel, and cobble. The bathymetric survey showed a relatively uniform sandy shoreface at each end of the reach that bounds more complex bathymetry in between, including irregular deposits of large boulders, cobble bars, and intertidal embayments. Much of the nearshore appeared to have relative abundance and diversity of submerged aquatic vegetation, dominated by surf grass and kelp. This topo-bathymetric survey enables the assessment of how sediments supplied by bluff erosion are dispersed along the beach and throughout the nearshore zone to influence habitats. The U.S. Geological Survey are using these data to validate process-based models, including wave runup that drives erosion of the bluff toe and mixed-grain nearshore sediment transport. Such models are critical for predicting beach and bluff morphology change, the long-term coastal response to sea-level rise, and their associated effects on property, infrastructure, and habitats.
