Topographic survey data of Oxbow Reservoir, Placer County, California, October 2022

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Logan, Joshua B., and East, Amy E., 20231030, Topographic survey data of Oxbow Reservoir, Placer County, California, October 2022: data release DOI:10.5066/P9B39W4J, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P9B39W4J
   • https://www.sciencebase.gov/catalog/item/65135fb4d34eeedefc13c1fc

   This is part of the following larger work.
   Logan, Joshua B., and East, Amy E., 2023, Topographic survey data and digital elevation model of Oxbow Reservoir, Placer County, California, October 2022: data release DOI:10.5066/P9B39W4J, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

   Online Links:

   • https://doi.org/10.5066/P9B39W4J
   • https://www.sciencebase.gov/catalog/item/65135edad34eeedefc13bff0

   Other_Citation_Details:

   Suggested Citation: Logan, J.B. and East, A.E., 2023, Topographic survey data and digital elevation model of Oxbow Reservoir, Placer County, California, October 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P9B39W4J.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -120.74457
   East_Bounding_Coordinate: -120.73185
   North_Bounding_Coordinate: 39.00609
   South_Bounding_Coordinate: 39.00018
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/65135fb4d34eeedefc13c1fc?name=OxbowReservoirTopographicData_browse.jpg&allowOpen=true (JPEG)

   Topographic survey operations at Oxbow Reservoir.

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 26-Oct-2022

   Currentness_Reference:

   ground condition at time data were collected

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: comma-delimited text
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (26040)
   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: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in meters
      The horizontal datum used is NAD83 (National Spatial Reference System 2011) (EPSG:1116).
      The ellipsoid used is GRS 1980 (EPSG:7019).
      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 of 1988 (EPSG:5703), derived using GEOID18

      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:

      Explicit elevation coordinate included with horizontal coordinates

7. How does the data set describe geographic features?

   Attribute Table

   Table containing attribute information associated with the dataset (Source: Producer defined)

   pid

   Point ID (Source: producer defined) A unique identification code for the point.

   northing_utmz10_m

   Northing coordinate of data point relative to the NAD83 (National Spatial Reference System 2011) datum, projected in the Universal Transverse Mercator (UTM) Zone 10 North coordinate system, meters (EPSG:6339) (Source: Producer defined)

   Range of values
   Minimum:	4319243.450
   Maximum:	4319872.321
   Units:	meters

   easting_utmz10_m

   Easting coordinate of data point relative to the NAD83 (National Spatial Reference System 2011) datum, projected in the Universal Transverse Mercator (UTM) Zone 10 North coordinate system, meters (EPSG:6339) (Source: Producer defined)

   Range of values
   Minimum:	695311.088
   Maximum:	696397.091
   Units:	meters

   orthometric_ht_navd88_m

   Orthometric height of data point in meters relative to the North American Vertical Datum of 1988 (EPSG:5703), derived using the National Geodetic Survey GEOID03. (Source: Producer defined)

   Range of values
   Minimum:	350.566
   Maximum:	453.791
   Units:	meters

   horizontal_prec_95pcntcl

   Estimated horizontal precision at the 95 percent confidence level. Not applicable for base station position on CP512, denoted by NULL value for this point. (Source: Producer defined)

   Range of values
   Minimum:	0.009
   Maximum:	1.447
   Units:	meters

   vertical_prec_95pcntcl

   Estimated vertical precision at the 95 percent confidence level. Not applicable for base station position on CP512, denoted by NULL value for this point. (Source: Producer defined)

   Range of values
   Minimum:	0.017
   Maximum:	0.993
   Units:	meters

   Entity_and_Attribute_Overview: The first line of the csv file is a header line.
   Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Joshua B. Logan
   • Amy E. East
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   U.S. Geological Survey, Pacific Coastal and Marine Science Center

   Attn: PCMSC Science Data Coordinator

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov

Why was the data set created?

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: 26-Oct-2022 (process 1 of 1)

   A topographic survey was conducted using two multi-constellation dual-frequency RTK GNSS rovers (Trimble R10-2) receiving differential corrections from a GNSS base station operating less than 1 kilometer away. The rovers were mounted on GPS backpacks, and were operated in continuous survey mode, collecting data at rate of 1 Hz. The surveyors walked on all exposed reservoir sediment bars which were accessible during the survey. The surveyors attempted to survey along breaks in slope, water surface elevation contours, with additional data in broad planar areas in order to adequately define the topographic surface. Additional survey data were collected along pre-defined "zig-zag" transects which could be re-occupied with a boat during a possible future bathymetric survey with the reservoir at full pool.
   The GNSS base station was placed on an existing control point, "CP512", on the west shoulder of Tahoe National Forest Road 0023-004, approximately 100 meters north of the reservoir below the junction with Forest Road 0023 and Forest Road 0023-02. The reference position provided for CP512 were: CP512-PCWA (SPCS83 California zone 2, ft) Northing: 2129745.418 Easting: 6919711.944 Elevation: 1486.07 (assumed ft., NGVD29)
   During the RTK survey, the GNSS base station was set to collect static observations, and these were submitted to the National Geodetic Survey (NGS) Online Positioning User Service (OPUS-S). The OPUS solution was of high quality, conforming to USGS Level III quality for a single-base OPUS-S survey. The coordinates of the OPUS-S solution are below: CP512-USGS (NAD83(2011) UTM Zone 10, meters) Northing: 4319590.574 Easting: 695699.448 Elevation: 453.791 (NAVD88, meters, derived using GEOID18)
   The newly derived position for CP512 was used to adjust all of the topographic survey data collected during the survey. Survey points with estimated vertical uncertainty greater than 1 meter were removed from the data set. Person who carried out this activity:
   

   Joshua Logan

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

   2885 Mission Street

   Santa Cruz, CA
   

   831-460-7519 (voice)

   jlogan@usgs.gov

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?
   No formal attribute accuracy tests were conducted.
2. How accurate are the geographic locations?
   The topographic survey data used to create the DEM were collected using multi-constellation dual-frequency RTK GNSS rovers receiving differential corrections from a base station operating less than 1 kilometer away. The average estimated horizontal precision of the topographic survey data was 0.028 meters at the 95 percent confidence level. Additional uncertainty related to the reference position of the GNSS base station is estimated to be 0.040 at the 95 percent confidence level, based on the NGS OPUS position solution report which was used to derive the position. Combining the estimated single point precision of the topographic survey data with the estimated uncertainty in the position of the GNSS base station reference point results in a total estimated horizontal accuracy of 0.049 meters at the 95 percent confidence level. Additional sources of error such as antenna height measurement errors, and errors resulting from the GPS antenna not being perfectly level during continuous surveying sessions may be present in the data, but the magnitudes of such errors are unknown.
3. How accurate are the heights or depths?
   The topographic survey data used to create the DEM were collected using multi-constellation dual-frequency RTK GNSS rovers receiving differential corrections from a base station operating less than 1 kilometer away. The average estimated vertical precision of the topographic survey data was 0.058 meters at the 95 percent confidence level. Additional uncertainty related to the reference position (orthometric height) of the GNSS base station is estimated to be 0.125 meters at the 95 percent confidence level, based on the NGS OPUS position solution report which was used to derive the position. Combining the estimated single point precision of the topographic survey data with the estimated uncertainty in the position of the GNSS base station reference point results in a total estimated vertical accuracy of 0.138 meters at the 95 percent confidence level. Additional sources of error such as antenna height measurement errors, and errors resulting from the GPS antenna not being perfectly level during continuous surveying sessions may be present in the data, but the magnitudes of such errors are unknown.
4. Where are the gaps in the data? What is missing?
   Dataset is considered complete for the information presented, as described in the abstract. During the survey significant portions of the reservoir bottom remained under water and inaccessible to surveyors. Consequently, this DEM covers approximately 50 percent of the total surface area of the reservoir at full pool.
5. How consistent are the relationships among the observations, including topology?
   No formal logical accuracy tests were conducted.

How can someone get a copy of the data set?

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
   

   United States

   1-888-275-8747 (voice)

   sciencebase@usgs.gov
2. What's the catalog number I need to order this data set? The topographic survey data are available in a comma-delimited text format.
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?
   • Availability in digital form:

     Data format:	The csv file contains topographic survey data. in format comma-delimited text (version Notepad++ v 7.8.6) Size: 1.42
     Network links:	https://doi.org/10.5066/P9B39W4J https://www.sciencebase.gov/catalog/file/get/65135fb4d34eeedefc13c1fc?name=OxbowReservoir_2022-10-26_topographic_points.csv https://www.sciencebase.gov/catalog/item/65135fb4d34eeedefc13c1fc

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?
   The downloadable data file is available in comma-separated values (CSV) spreadsheet format. Text editing software can be used to open the file, as well as spreadsheet programs, such as Microsoft Excel.

Who wrote the metadata?

Dates:

Last modified: 30-Oct-2023

Metadata author:

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

Attn: PCMSC Science Data Coordinator

2885 Mission Street

Santa Cruz, CA

831-427-4747 (voice)

pcmsc_data@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)