Identification_Information:
  Citation:
    Citation_Information:
      Originator: Tom Coons
      Originator: Christopher E. Soulard
      Originator: Noah Knowles
      Publication_Date: 2008
      Title: High Resolution Digital Terrain Models of the Sacramento/San Joaquin Delta Region
      Geospatial_Data_Presentation_Form: raster digital data
      Series_Information:
        Series_Name: Digital Data Series
      Publication_Information:
        Publication_Place: Western Geographic Science Center
        Publisher: U.S. Geological Survey
      Online_Linkage: http://pubs.usgs.gov/ds/359/
  Description:
    Abstract: The U.S. Geological Survey (USGS) Western Region Geographic Science Center, in conjunction with the USGS Water Resources Western Branch of Regional Research, has developed a high-resolution elevation dataset covering the Sacramento/San Joaquin Delta region of California. The elevation data were compiled photogrammically from aerial photography (May 2002) with a scale of 1:15,000. The resulting dataset has a 10-meter horizontal resolution grid of elevation values. The vertical accuracy was determined to be 1 meter. Two versions of the elevation data are available: the first dataset has all water coded as zero, whereas the second dataset has bathymetry data merged with the elevation data. The projection of both datasets is set to UTM Zone 10, NAD 1983. The elevation data are clipped into files that spatially approximate 7.5-minute USGS quadrangles, with about 100 meters of overlap to facilitate combining the files into larger regions without data gaps. The files are named after the 7.5-minute USGS quadrangles that cover the same general spatial extent. File names that include a suffix (_b) indicate that the bathymetry data are included (for example, sac_east versus sac_east_b). These files are provided in ESRI Grid format. This metadata represents a project level description, and accounts for the variety of techniques applied to compile the entire dataset rather than detailing the methods involved in creating each file.
    Purpose: The United States Geological Survey (USGS) Western Region Geographic Science Center and USGS Water Resources Western Branch of Regional Research have developed a high-resolution digital elevation dataset in an effort to assess the implications of climate change and potential levee failure in the Sacramento/San Joaquin Delta region of California. The data are being used to (1) investigate the influence of potential levee failures on the physical and biochemical systems of the Delta, (2) characterize events that may follow breaching of one or more major levees, and (3) assess the risk of such levee failures and other areas at risk of inundation as a result of rising sea levels. These applications are being carried out by researchers associated with the USGS CASCaDE (Computational Assessments of Scenarios of Change for the Delta Ecosystem) project and with the Scripps Institution of Oceanography.
    Supplemental_Information: This is not a LIDAR-based elevation dataset. Elevation data were derived through photogrammetric methods. Manual edits were made to this dataset to ensure all elevations represent, as accurately as possible, deviations from local mean sea level. Earlier steps in this effort involved a much coarser dataset. A summary of this work is available online (http://tenaya.ucsd.edu/~knowles/posterstalks/BayDeltaSeaLevelRise_NoahKnowles.pdf).
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 200205
    Currentness_Reference: ground condition
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate:
      East_Bounding_Coordinate:
      North_Bounding_Coordinate:
      South_Bounding_Coordinate:
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: DTM
      Theme_Keyword: terrain
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: elevation
    Place:
      Place_Keyword_Thesaurus: None
      Place_Keyword: Sacramento County
      Place_Keyword: San Joaquin County
      Place_Keyword: California
    Stratum:
    Temporal:
      Temporal_Keyword_Thesaurus: None
      Temporal_Keyword: 200205
  Access_Constraints: None
  Use_Constraints: None. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data.
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Christopher E. Soulard
        Contact_Organization: U.S. Geological Survey
      Contact_Position: Physical Scientist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 345 Middlefield Road, MS-531
        City: Menlo Park
        State_or_Province: California
        Postal_Code: 94025
        Country: USA
      Contact_Voice_Telephone: (650)329-4317
      Contact_Electronic_Mail_Address: csoulard@usgs.gov
  Data_Set_Credit: Tom Coons, U.S. Geological Survey
  Security_Information:
    Security_Classification_System: None
    Security_Classification: Unclassified
  Native_Data_Set_Environment: Zeiss ZI, BAE Systems SocetSet 5.2, Global Mapper 7, and ESRI ArcCatalog 9.2
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report: The attribute accuracy is dependent upon the accuracy of the aerial photography and the errors associated with the automated procedures used to derive generate the elevation dataset. Besides manual checks of the elevation data against flight control points and ancillary data sources, no specific field tests for attribute accuracy were conducted on the data. Coordinates in the elevation files have four implied decimal places. The positional accuracy of these coordinates may not be as great as the four decimal places suggest.
    Quantitative_Attribute_Accuracy_Assessment:
  Logical_Consistency_Report: Flight field points and ancillary data (including but not limited to, USGS DOQs, USGS DRGs, and expert opinion) checks were made by the technician in 2007 to test horizontal/vertical accuracy and the topographic consistency of the elevation dataset. Manual edits were made by the technician to reduce systematic errors arising from automated steps in the DTM creation process.
  Completeness_Report: Elevation data are limited to areas included in the original aerial photography. Each file may have areas where elevation data are missing due to the spatial extent of the original aerial photography. These areas are coded as null.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report: Horizontal accuracy was determined from aero-triangulation accuracy, airborne GPS, and GPS field control points.
      Quantitative_Horizontal_Positional_Accuracy_Assessment:
        Horizontal_Positional_Accuracy_Value: .5
        Horizontal_Positional_Accuracy_Explanation: No aero-triangulated blocks produced a RMS exceeding .5 meters.
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report: Most of the postings were at 2 to 4 meters, with some at 20 meters. The entire dataset was resampled to 10 meter postings.
      Quantitative_Vertical_Positional_Accuracy_Assessment:
        Vertical_Positional_Accuracy_Value: 1.0
        Vertical_Positional_Accuracy_Explanation: Accuracy estimates were derived by visually checking auto-correlated data against aero-triangulated data, field control points (XYZ), and ancillary vertical data sources. Any points exceeding 1 meter (spikes) were manually edited by the technician.
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Hammon, Jensen, Wallen, and Associates
          Publication_Date: 2002
          Title: Aerial Photography of the Sacramento/San Joaquin Delta region: Aerial Photography and Field Control.
          Geospatial_Data_Presentation_Form: photographic diapositive
      Source_Scale_Denominator: 15000
      Type_of_Source_Media: photographic diapositive
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 200205
        Source_Currentness_Reference: ground condition
      Source_Citation_Abbreviation: AERIAL_PHOTO
      Source_Contribution: Elevation data were derived from natural color aerial photography flown at 7500 feet with a six inch lens. Airborne GPS was collected for all flights and was used for the triangulation adjustments. Photography was flown in May 2002 by Hammon, Jensen, Wallen, and Associates.
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Foxgrover, A.
          Originator: Smith, R.E.
          Originator: Jaffe, B.E.
          Publication_Date: 2007
          Title: Suisun Bay and Delta Bathymetry
          Geospatial_Data_Presentation_Form: raster digital data
          Online_Linkage: http://sfbay.wr.usgs.gov/sediment/delta/index.html
      Source_Scale_Denominator: Varies
      Type_of_Source_Media: online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 2007
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: BATHYMETRY
      Source_Contribution:
        The initial data used for the Delta grid were:

        Major streams coverage: The US Bureau of Reclamation created a single cover of the Delta hydrology based on 1:24000 quadrangle maps.

        Soundings: The California Department of Water Resources combined soundings collected by several agencies, including, NOAA, DWR, USGS, USBR, and COE. These soundings were corrected to a common datum (NGVD29) and combined into a single database. 

        Ortho photography: Orthoquads based on a 1992 aerial survey, resolution 1:12000.
    Process_Step:
      Process_Description:
        Elevation data were derived from natural color aerial photography flown at an altitude of 7,500 feet with a 6-inch lens. Photography was flown in May 2002 by Hammon, Jensen, Wallen, and Associates. The aerial photography, which has a scale of 1:15,000, was scanned to produce a ground pixel size of approximately 1 foot. Photogrammetric methods were applied to the scanned photography to derive the elevation data. The processing steps for the dataset varied across the study area and required the use of four software systems (Zeiss ZI, BAE Systems SocetSet 5.2, Global Mapper 7, and ESRI ArcCatalog 9.2). In this report, these processing techniques are summarized for the entire dataset rather than detailing the methods involved in creating each file. The resulting dataset has a 10-meter horizontal-resolution grid of elevation values. Airborne Global Positioning System (GPS) points, Field control points (XYZ), ancillary geospatial control points, and manual editing were used to ensure that all horizontal locations (XY) were accurate and that all vertical-elevation values (Z) represent deviations from local mean sea level as accurately as possible.
        Three different software methods were used to create digital terrain models (DTMs) for the Sacramento/San Joaquin Delta region. An autotriangulation technique was applied to nearly 70 percent of the study area by using Zeiss ZI Imaging Station Image Station Automated Triangulation (ISAT). DTMs were collected at 4-meter postings for all individual models by using Image Station Automated Elevations (ISAE) point matching. All files were saved as grid files by using the Zeiss ZI que file option. The individual model files were imported into BAE Systems SocetSet 5.2 in groups of about 50 models before any editing was done. A secondary software method involved performing the autotriangulation by using BAE Systems SocetSet 5.2 Multi Sensor Triangulation (MST). DTMs were collected at 2-meter postings by using BAE Systems SocetSet 5.2 point-matching techniques. Initial editing was performed by using project photography stereo models as ground truth, and this method was applied to about 20 percent of the study area. The third method used to create DTMs involved soft-copy techniques employed by Hammon, Jensen, Wallen, and Associates. Terrain models were collected by Hammon, Jensen, Wallen, and Associates (for about 10 percent of the study area) at about 20-meter postings by using point-matching techniques. 
        All files created through the processes above were imported into BAE Systems SocetSet 5.2 and resampled to 10-meter postings. USGS digital orthophoto quadrangles (DOQs), USGS quadrangle maps (DRGs), and other ancillary data were used as ground truth in checking spikes in the elevation data (USGS National Geospatial Program, 1997). 
        A large part of creating these data involved masking out water bodies from the land elevations. The water mask was developed from DRGs (65 percent), with the remaining areas determined by project photography and DOQs. Water bodies were set to zero for the first dataset, or null as an intermediate step in creating a second dataset that included bathymetry values for water bodies. The combined dataset, or second dataset, was made with the DTM null tagged value file merged over the GS bathymetry file. The bathymetry data are input only where there is a null DTM value. Areas of overlap (null in both the DTM and bathymetry files) were set to 0 and stripped of the null tag. Areas outside of the study area were coded as null values. The datum of the bathymetry dataset was not changed before these data were merged with the land elevation data. NAVD88 (land) and NGVD29 (bathymetry) differ by roughly 1 meter. 
        The complete elevation dataset was clipped into files that spatially approximate the USGS 7.5-minute map grid and were exported by using BAE Systems SocetSet 5.2. These 23 files, which have about 100 meters of overlap added to each file to facilitate combining the files into larger regions without data gaps, were imported into ESRI ArcCatalog 9.2 and converted to ESRI Grid files. The files were named after the 7.5-minute USGS quadrangles that cover the same general spatial extent. File names that include a suffix (_b) indicate that the bathymetry data are included (for example, sac_east versus sac_east_b).
      Process_Date: 2007
Spatial_Data_Organization_Information:
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
  Vertical_Coordinate_System_Definition:
    Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Distance_Units: meters
    Depth_System_Definition:
      Depth_Datum_Name: National Geodetic Vertical Datum of 1929
      Depth_Distance_Units: meters
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
        Contact_Person: Christopher E. Soulard
      Contact_Position: Physical Scientist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 345 Middlefield Road, MS-531
        City: Menlo Park
        State_or_Province: California
        Postal_Code: 94025
        Country: USA
      Contact_Voice_Telephone: (650)329-4317
      Contact_Electronic_Mail_Address: csoulard@usgs.gov
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: ESRI Grid
        Format_Version_Number: Created in ESRI ArcCataolog 9.2
        File_Decompression_Technique: WinZip
      Digital_Transfer_Option:
        Online_Option:
          Online_Computer_and_Operating_System: http://pubs.usgs.gov/ds/359/
    Fees: None
    Ordering_Instructions: Elevation data are available online at no charge. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data.
    Turnaround: None
Metadata_Reference_Information:
  Metadata_Date: 20080717
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
        Contact_Person: Christopher E. Soulard
      Contact_Position: Physical Scientist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 345 Middlefield Road, MS-531
        City: Menlo Park
        State_or_Province: CA
        Postal_Code: 94025
        Country: USA
      Contact_Voice_Telephone: (650)329-4317
      Contact_Electronic_Mail_Address: csoulard@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Access_Constraints: None
  Metadata_Use_Constraints: None
  Metadata_Security_Information:
    Metadata_Security_Classification: Unclassified