Beach topography and nearshore bathymetry of Humboldt Bay North Spit and South Spit, California

Repeat topographic and bathymetric surveys were performed by the U.S. Geological Survey along Humboldt Bay North Spit and South Spit within the Eureka littoral cell in northern California. The surveys were used to characterize changes in coastal morphology and sand volume within an area that extends approximately 12 km north and 8 km south of the Humboldt Bay inlet. Bathymetric and topographic data were collected primarily on a series of shore normal transects spaced at 130 m to 250 m intervals that extend from approximately 13 m water depth to just landward of the primary dune crest. The bathymetric surveys were performed using personal watercraft equipped with single beam echosounders and dual frequency global satellite navigation system (GNSS) receivers. Topographic measurements were collected by surveyors on foot with GNSS receivers mounted to backpacks. Additional topographic data were collected between survey lines in some areas with an all-terrain vehicle equipped with a GNSS receiver. These data were collected to inform management of sediment dredged from the bar and entrance channel of Humboldt Bay by the U.S. Army Corps of Engineers.