San Francisco Bay Multi-beam Backscatter Imagery: Area A

Backscatter imagery 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 backscatter 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.

10019

Seven survey blocks in Area A were acquired with a Reson 7101 multibeam sonar. The multi-beam backscatter imagery 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.

None

These multi-beam backscatter mosaic images 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.

Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.1.1.3143

The attributes of these data include positioning and backscatter intensity values.

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 backscatter imagery 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 multibeam backscatter data that exceeded IHO Order 1A standards. Overlapping features in the backscatter data were examined visually to confirm accuracy standards were met.; Quantitative Value: 0.6 meters, Test that produced the value: Maximum Total Propagated Uncertainty in meters

N/A - no vertical accuracy can be attributed to the imagery product.

This data set was derived by mosaicking together lines in each survey block to generate a series of backscatter images throughout the survey area. No survey blocks contain missing data.

Overlapping data sets were analyzed for agreement. Imagery was visually inspected for artifacts and noise within each survey block.