Nearshore bathymetry of Humboldt Bay North Spit and South Spit, California

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Metadata:

Identification_Information
Data_Quality_Information
Spatial_Data_Organization_Information
Spatial_Reference_Information
Entity_and_Attribute_Information
Distribution_Information
Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Andrew W. Stevens
Originator: Josh B. Logan
Originator: Jackson E. Currie
Originator: Timothy C. Elfers
Originator: Kai A. Parker
Publication_Date: 20260604
Title:

Nearshore bathymetry of Humboldt Bay North Spit and South Spit, California

Geospatial_Data_Presentation_Form: comma-delimited text
Series_Information:

Series_Name: data release
Issue_Identification: DOI:10.5066/P1SNSQB9

Publication_Information:

Publication_Place:

Pacific Coastal and Marine Science Center, Santa Cruz, California

Publisher: U.S. Geological Survey

Online_Linkage: https://doi.org/10.5066/P1SNSQB9
Larger_Work_Citation:

Citation_Information:

Originator: Andrew W. Stevens
Originator: Josh B. Logan
Originator: Jackson E. Currie
Originator: Timothy Elfers
Originator: Kai A. Parker
Publication_Date: 2026
Title:

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

Series_Information:

Series_Name: data release
Issue_Identification: DOI:10.5066/P1SNSQB9

Publication_Information:

Publication_Place: Pacific Coastal and Marine Science Center, Santa Cruz, CA
Publisher: U.S. Geological Survey

Other_Citation_Details:

Suggested Citation: Stevens, A.W., Logan, J.B., Currie, J.E., Elfers, T.C., and Parker, K.A., 2026, Beach topography and nearshore bathymetry of Humboldt Bay North and South Spits, California: U.S. Geological Survey data release, https://doi.org/10.5066/P1SNSQB9.

Online_Linkage: https://doi.org/10.5066/P1SNSQB9

Description:

Abstract:

Bathymetric data of the nearshore zone were collected along Humboldt Bay North and South Spits, California using personal watercraft (PWCs) equipped with single-beam sonar systems and global navigation satellite system (GNSS) receivers. This data release currently contains bathymetric data from 2 surveys performed between April 2025 and September 2025 and will be updated when additional surveys become available.

Purpose:

Data were obtained to quantify changes in coastal morphology and sand volume within an area that extends approximately 12 kilometers (km) north and 8 km south of the Humboldt Bay inlet. Analysis derived from these data were used to inform management of sediment dredged from the bar and entrance channel of Humboldt Bay by the U.S. Army Corps of Engineers.

Supplemental_Information:

Additional information about the field activities from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2025-615-FA https://cmgds.marine.usgs.gov/fan_info.php?fan=2025-658-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20250429
Ending_Date: 20250917

Currentness_Reference: Ground condition at time data were collected

Status:

Progress: In work
Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -124.2866575
East_Bounding_Coordinate: -124.1677396
North_Bounding_Coordinate: 40.8666435
South_Bounding_Coordinate: 40.7000867

Keywords:

Theme:

Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:34177f4c-ee07-4229-b387-de609d0006a2

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: elevation

Theme:

Theme_Keyword_Thesaurus: Data Categories for Marine Planning
Theme_Keyword: Bathymetry and Elevation

Theme:

Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: bathymetry
Theme_Keyword: GPS measurement
Theme_Keyword: sea-floor characteristics
Theme_Keyword: marine geophysics
Theme_Keyword: single-beam echo sounder

Theme:

Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) keywords
Theme_Keyword: Global Positioning System (GPS) observations

Theme:

Theme_Keyword_Thesaurus: None
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Coastal and Marine Hazards and Resources Program
Theme_Keyword: CMHRP
Theme_Keyword: Pacific Coastal and Marine Science Center
Theme_Keyword: PCMSC

Place:

Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Humboldt County
Place_Keyword: North Spit
Place_Keyword: South Spit
Place_Keyword: Humboldt Bay

Access_Constraints: No access constraints
Use_Constraints:

USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. These data are marked with a Creative Commons CC0 1.0 Universal License. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

U.S. Geological Survey, Pacific Coastal and Marine Science Center

Contact_Person: PCMSC Science Data Coordinator

Contact_Address:

Address_Type: mailing and physical
Address: 2885 Mission Street
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060

Contact_Voice_Telephone: 831-427-4747
Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov

Native_Data_Set_Environment: MATLAB Version: 25.2.0.2998904 (R2025a)

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report: No formal attribute accuracy tests were conducted.

Logical_Consistency_Report: No formal logical accuracy tests were conducted.
Completeness_Report:

Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Manufacturer reported accuracy for the differentially corrected horizontal positions for both bathymetric and topographic measurements is 0.8 cm + 0.5 ppm, where ppm refers to baseline distances between GNSS rovers and base stations in parts per million. Mean and maximum baselines from the GNSS base station during the survey were 3.1 km and 6.3 km, respectively suggesting a mean and maximum horizontal accuracy of bathymetric and topographic positions to be between 0.67 centimeters (cm) and 0.82 cm relative to the base station coordinate. Uncertainty in the horizontal positions associated with pitch and roll of the survey vessels during data collection is unknown.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

Uncertainty in the vertical positions of the GNSS measurements was estimated based on the accuracy of the Trimble GNSS rovers used in the survey. Manufacturer reported accuracy for the differentially corrected vertical positions for the GNSS rover trajectories is 1.5 cm + 1 ppm. The maximum baseline from the GNSS base station during the survey was 6.3 km, suggesting a minimum vertical accuracy of 2.76 cm relative to the base station coordinate. The bathymetric measurements include additional sources of vertical uncertainty associated with the CEEHydrosystems CEESCOPE single beam echosounder systems used in this survey. The manufacturer of the single beam echosounders reports a vertical uncertainty of 1 cm + 1 percent of water depth. Based on a mean (7 m) and maximum water depth (23.7 m) measured during the survey, the mean and maximum vertical uncertainty for the bathymetric soundings is estimated to be 8 and 24 cm, respectively. Combining the uncertainty related to the GNSS positions and bathymetric soundings in quadrature yields a total mean and max vertical uncertainty of 8.5 and 24.2 cm respectively for the final bathymetric elevations. Uncertainty in the vertical positions associated with pitch and roll of the survey vessels is unknown.

Lineage:

Process_Step:

Process_Description:

Geodetic control for the project was established using simultaneous static GNSS network surveys on four benchmarks installed near the study area. Static GNSS occupations were conducted on these benchmarks during February, April, and May 2025. Observation data from each session were processed using the National Geodetic Survey’s Online Positioning User Service (OPUS) Projects. All static observations used in the network adjustment met USGS Level I quality standards for single-base OPUS-S surveys. The resulting geodetic control is aligned to the National Spatial Reference System (NSRS) through the North American Datum of 1983, National Adjustment of 2011 (NAD83(2011)), at epoch 2010.00. Elevations are referenced to the North American Vertical Datum of 1988 (NAVD88), with orthometric heights computed using NGS GEOID18.

Process_Date: 2025

Process_Step:

Process_Description:

Bathymetric data were acquired using single-beam sonar systems and global navigation satellite systems (GNSS) receivers mounted on personal watercraft (PWC). Depths from the echosounders were computed using sound velocity profiles measured using a CTD during the survey. Positioning of the survey vessels was determined at 10 Hz using dual frequency GNSS receivers. Output from the GNSS receivers and sonar systems were combined in real time by a computer running HYPACK hydrographic survey software. Navigation information was displayed on a video monitor, allowing vessel operators to navigate along planned survey lines.

Process_Date: 20250917

Process_Step:

Process_Description:

Precise positioning of the bathymetric platforms was achieved with a single GNSS base station transmitting differential corrections in real time via UHF radio modem at 1-Hz intervals. Positioning data from the bathymetric survey platforms were later post-processed using Waypoint Grafnav to apply differential corrections from the GNSS base station. These post-processed positions superseded those that were recorded in the field. Orthometric elevations relative to the NAVD88 vertical datum were computed using the National Geodetic Survey Geoid18 geoid model. Bathymetric data were merged with post-processed positioning data and spurious soundings were removed using a custom Graphical User Interface (GUI) programmed with the computer program MATLAB. The final point data are projected in cartesian coordinates using the Universal Transverse Mercator (UTM), Zone 10N meters coordinate system.

Process_Date: 20250923

Process_Step:

Process_Description:

All available bathymetric data from the surveys were compiled into a comma-delimited text files (one file for each survey) for distribution

Process_Date: 20250925

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Point
Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: Point
Point_and_Vector_Object_Count: 808183

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 0.0000001
Longitude_Resolution: 0.0000001
Geographic_Coordinate_Units: Decimal degrees

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: GRS_1980
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257222101

Vertical_Coordinate_System_Definition:

Altitude_System_Definition:

Altitude_Datum_Name: North American Vertical Datum of 1988
Altitude_Resolution: 0.01
Altitude_Distance_Units: meters
Altitude_Encoding_Method:

Explicit elevation coordinate included with horizontal coordinates

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: hb[yy]_[mmm]_bathy.csv
Entity_Type_Definition:

Table containing attribute information associated with the bathymetry dataset, where [yy]_[mmm] in the file name is the year and month in which the data were collected.

Entity_Type_Definition_Source: Producer defined

Attribute:

Attribute_Label: line_number
Attribute_Definition:

Numeric code identifying the number of the survey line. Data that were not collected along a survey line are labeled "None".