San Francisco Bay Multi-beam Bathymetry: Area A

These multi-beam bathymetric data were collected over shallow subtidal areas in the San Francisco Bay estuary system. Bathymetric and acoustic backscatter data were collected simultaneously in 84 survey blocks. Seventy five of these blocks were surveyed with 100% cover of backscatter imagery and nine blocks were surveyed with 50% backscatter coverage. These data were collected as source material for planned benthic habitat mapping. An earlier project had been completed to map the very-shallow subtidal and intertidal areas. These mosaics were collected with the Reson Seabat 7101 multibeam sonar system in the San Francisco Bay. For this San Francisco Bay habitat mapping project, seven survey blocks were acquired with the Reson 7101 sonar, as these seven areas contained water depths that were predominantly deeper than 20 meters.

Original contact information:

Contact Name: Jen Eckerle

Contact Org: California Ocean Protection Council (OPC)

Title: Deputy Director, OPC

Phone: 916-653-9416

Email: jen.eckerle@resources.ca.gov

The primary purpose of this acoustic bathymetry acquisition is to provide the California Ocean Protection Council (OPC), as required for the California Seafloor Mapping Program (CSMP) modern, accurately positioned sonar imagery data of San Francisco Bay coastal and near shore waters to delineate marine habitat types. Secondarily, the survey shall provide OPC and NOAA with bathymetric survey data from a combination of multi-beam and interferometric sonars. The combined survey data, including the imagery and the bathymetry, will support OPC's goals as well as assist with NOAA's mandate for port and harbor maintenance (dredging), coastal engineering (beach erosion and replenishment studies), and coastal zone management.

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Seven survey blocks in Area A were acquired with a Reson 7101 multibeam sonar. The bathymetric products are organized by these blocks. The blocks represent the priority areas determined by the project partners and were arranged to avoid areas where data had already been collected. Data for each block was collected on the following dates. Block CA1B08 was acquired between 12/21/2014 and 12/21/2014. Block CA1B09 was acquired between 12/21/2014 and 12/21/2014. Block CA1B22 was acquired between 12/13/2014 and 12/16/2014. Block CA1B24 was acquired between 12/10/2014 and 12/13/2014. Block CA1B26 was acquired between 12/14/2014 and 12/15/2014. Block NA1B15 was acquired between 12/16/2014 and 12/21/2014. Block NA1B23 was acquired between 12/18/2014 and 12/18/2014.

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These bathymetry files depict the existing conditions of the seafloor at the time of the survey and are only accurate for that time. Use of these products is to be determined by the California Ocean Protection Council.

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These data are not attributed.

Multi-beam data met IHO Order 1A specifications, meaning the horizontal accuracy of multibeam data had to be within 5 meters + 5% of depth. The actual horizontal accuracy of the bathymetry exceeded these requirements, as the navigation/position data for the vessel was post-processed using an Applanix SmartBase post-processed kinematic solution, resulting in vessel horizontal positioning RMS values under 5 centimeters. Likewise, the vessel equipment offsets were measured to an accuracy of approximately 1 centimeter (1 sigma level) using a Total Station. Vessel roll and pitch were measured to an accuracy of approximately 0.02 degrees (1 sigma level) using an Applanix POS MV. These factors created highly accurate horizontal positioning of the data that exceeded IHO Order 1A standards. Overlapping features in the bathymetry were examined to confirm accuracy standards were met.; Quantitative Value: 0.6 meters, Test that produced the value: Approximated maximum total propagated uncertainty in meters

Multibeam data met IHO Order 1A specifications. QC procedures confirmed that these standards were met or exceeded. QC procedures included bar check calibrations, tide comparisons of observed tides vs. GPS-derived tides, analysis of propagated uncertainty in the CARIS CSAR surface, and IHO Order 1A crossline analysis.; Quantitative Value: 0.6 meters, Test that produced the value: Maximum Total Propagated Uncertainty in meters

The data set was derived after manually rejecting erroneous soundings. The final bathymetric product was generated using a CUBE surface model of the cleaned bathymetry.

QC procedures confirmed that these standards were met or exceeded. QC procedures included bar check calibrations, tide comparisons of observed tides vs. GPS-derived tides, analysis of propagated uncertainty in the CARIS CSAR surface, and IHO Order 1A crossline analysis.