Bathymetric DEM of the Sacramento River, from the Feather River to Knights Landing, California in February 2011

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Frequently anticipated questions:


What does this data set describe?

Title:
Bathymetric DEM of the Sacramento River, from the Feather River to Knights Landing, California in February 2011
Abstract:
This part of the data release presents a digital elevation model (DEM) created from bathymetry data collected on February 1, 2011, in the Sacramento River from the confluence of the Feather River to Knights Landing. The data were collected by the USGS Pacific Coastal and Marine Science Center (PCMSC) team with collaboration and funding from the U.S. Army Corps of Engineers. This project used interferometric sidescan sonar to characterize the riverbed and channel banks along a 12 mile reach of the Sacramento River, California (River Mile 79 through River Mile 91) to aid in the understanding of fish response to the creation of safe habitat associated with levee restoration efforts in two 1.5 mile reaches of the Sacramento River between River Mile 80 and 86.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: http://cmgds.marine.usgs.gov/fan_info.php?fan=S0311CA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Fregoso, Theresa A., Finlayson, David P., Smith, David L., Mulvey, Brian M., Reiss, Thomas E., and Jaffe, Bruce E., 2017, Bathymetric DEM of the Sacramento River, from the Feather River to Knights Landing, California in February 2011: data release DOI:10.5066/F72B8W65, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Fregoso, Theresa A., Finlayson, David P., Smith, David L., Mulvey, Brian M., Reiss, Thomas E., and Jaffe, Bruce E., 2017, Bathymetry and acoustic backscatter data of the Sacramento River, from the Feather River to Knights Landing, California in February, 2011: data release DOI:10.5066/F72B8W65, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.726043
    East_Bounding_Coordinate: -121.611995
    North_Bounding_Coordinate: 38.820108
    South_Bounding_Coordinate: 38.758167
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5898cdc1e4b0efcedb707561?name=SacRiverBathyDEM2011.png&allowOpen=true (PNG)
    image map showing the 0.5 m resolution digital elevation model (DEM) of the Sacramento River, color-coded to show elevation in meters, with zoomed insets of different areas.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 01-Feb-2011
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: ESRI Raster GRID
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a raster data set. It contains the following raster data types:
      • Dimensions 13465 x 19619, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.5
      Ordinates (y-coordinates) are specified to the nearest 0.5
      Planar coordinates are specified in METERS
      The horizontal datum used is D NAD 1983 CORS96.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum 1988(NAVD88)
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    ASCII File
    ASCII file containing elevation data associated with the digital elevation model (DEM). Cells with values of -9999 in the ASCII file indicate no data. The ASCII file consists of header information containing a set of keywords, followed by cell values in row-major order. The file format is:
    
    <NCOLS xxx>
    <NROWS xxx>
    <XLLCENTER xxx | XLLCORNER xxx>
    <YLLCENTER xxx | YLLCORNER xxx>
    <CELLSIZE xxx>
    {NODATA_VALUE xxx}
    row 1
    row 2
    .
    .
    .
    row n
    
    
    where xxx is a number, and the keyword nodata_value is optional and defaults to -9999. Row 1 of the data is at the top of the grid, row 2 is just under row 1 and so on. The nodata_value is the value in the ASCII file to be assigned to those cells whose true value is unknown. In the grid they will be assigned the keyword NODATA. Cell values are be delimited by spaces. No carriage returns are necessary at the end of each row in the grid (although they are included in this case). The number of columns in the header is used to determine when a new row begins. The number of cell values is equal to the number of rows times the number of columns. (Source: Producer Defined)
    Value
    Orthometric Altitude (elevation) relative to NAVD88 in meters. Values are positive up. (Source: Producer Defined)
    Range of values
    Minimum:-13.34
    Maximum:4.67
    Units:meters
    Resolution:.01

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Theresa A. Fregoso
    • David P. Finlayson
    • David L. Smith
    • Brian M. Mulvey
    • Thomas E. Reiss
    • Bruce E. Jaffe
  2. Who also contributed to the data set?
    The U.S. Geological Survey would also like to acknowledge the U.S. Army Corps of Engineers for their help collecting these data
  3. To whom should users address questions about the data?
    Teresa Fregoso
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission St.
    Santa Cruz, CA
    USA

    831-460-7528 (voice)
    tfregoso@usgs.gov

Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify bathymetric features.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2011 (process 1 of 2)
    Acoustic-survey data were collected using a 468.75 kHz SEA (Systems Engineering & Assessment Ltd) SWATHplus-H phase-differencing sidescan sonar. The survey vessel was equipped with a CodaOctopus F180 attitude and positioning system for the duration of the survey. The F180 received Real Time Kinematic (RTK) corrected Global Positioning System (GPS) data that were broadcast from shore to the survey vessel via UHF radio link. The RTK GPS data were combined with the inertial vessel motion measurements (pitch, roll, and heading) directly within the F180 hardware so that high-precision position and attitude corrections were fed in real time to the sonar acquisition equipment. Sound velocity measurements were collected continuously with an Applied Micro Systems Micro sound velocimeter deployed on the transducer frame for real-time sound velocity adjustments at the transducer-water interface. In addition, sound velocity profiles (SVPs) were collected with an Applied Micro Systems, SvPlus 3472. GPS data and measurements of vessel motion were combined in the F180 hardware to produce a high-precision vessel attitude packet. This packet was transmitted to the Swath Processor acquisition software in real-time and combined with instantaneous sound velocity measurements at the transducer head before each ping. The returned samples were projected to the seafloor using a ray-tracing algorithm working with the previously measured SVPs in SEA Swath Processor. A series of statistical filters were applied to the raw samples to isolate the seafloor returns from other spurious targets in the water column. Finally, the processed data were stored line-by-line in both raw (.sxr) and processed (.sxp) trackline files. The raw 16-bit backscatter data recorded simultaneously with bathymetry by the SWATHplus-H system was georeferenced and gain-normalized by the program SXPEGN, which was written by the USGS to enhance the backscatter imagery. The program normalizes for time-varying signal loss and beam directivity differences. The resulting normalized amplitude values are re-scaled to 16 bit, and gridded into a GeoJPEG using GRID Processor Software supplied by SEA. For further information on the parameters used for each instrument, see the accompanying methods summary in the report for the Data Release for S-03-11-CA.pdf (https://www.sciencebase.gov/catalog/file/get/588f8d74e4b072a7ac08c35e?name=Report_for_Data_Release_Survey_S-03-11-CA.pdf).
    Date: 2011 (process 2 of 2)
    CARIS HIPS and SIPS software was used to clean and bin the raw bathymetry data. Processed .sxp files were imported to CARIS and were filtered to remove obvious soundings, nadir gaps, and other artifacts. Base surfaces were exported as an ASCII table, which was then projected horizontally to the North American Datum of 1983 (NAD83). The data were then transformed vertically to the North American Vertical Datum of 1988 (NAVD88) using the Geoid09 model. Finally, the data were gridded using Surfer software at 0.5-m resolution and smoothed to fill small gaps in the surface and provide some relief from the statistical noise inherent to interferometric bathymetry data. This final surface was converted to an ESRI ASCII grid. For further information on the parameters used for each data-processing step, see the accompanying methods summary in this data release (https://www.sciencebase.gov/catalog/file/get/588f8d74e4b072a7ac08c35e?name=Report_for_Data_Release_Survey_S-03-11-CA.pdf).).
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    This bathymetric data has not been independently verified for accuracy.
  2. How accurate are the geographic locations?
    Estimated to be no less than 2 m, owing to water depth and total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations
  3. How accurate are the heights or depths?
    Estimated to be no less than 20 cm, owing to water depth and total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations.
  4. Where are the gaps in the data? What is missing?
    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.
  5. How consistent are the relationships among the observations, including topology?
    All bathymetric values are derived from the same instruments and processing workflow.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
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. Please recognize and acknowledge the U.S. Geological Survey and the U.S. Army Corps of Engineers as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? DEM grid is available in Esri ARC/INFO ASCII GRID format (SacRiver2011elev_nad83u10_NAVD88.asc), along with a low-resolution browse graphics of the DEM in png format (SacRiverbathyDEM2011.png) and associated FGDC-compliant metadata (SacRiver2011elev_nad83u10_NAVD88.xml).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data can be viewed with ESRI ArcGIS software.

Who wrote the metadata?

Dates:
Last modified: 26-Mar-2018
Metadata author:
Theresa A. Fregoso
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Geographer
2885 Mission Street
Santa Cruz, CA
United States of America

831-460-7528 (voice)
tfregoso@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/sf_bay_delta/SacRiver2011elev_nad83u10_NAVD88.faq.html>
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