Point shapefile of processed continuous resistivity profiling data below the sediment water interface collected in Greenwich Bay, Rhode Island, on May 15, 2009, on U.S. Geological Survey Field Activity 2009-021-FA (Geographic, WGS84)

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Frequently anticipated questions:

What does this data set describe?

Title:
Point shapefile of processed continuous resistivity profiling data below the sediment water interface collected in Greenwich Bay, Rhode Island, on May 15, 2009, on U.S. Geological Survey Field Activity 2009-021-FA (Geographic, WGS84)
Abstract:
As part of a larger investigation to understand groundwater-surface water interactions in Greenwich Bay, Rhode Island, a geophysical survey was conducted from a small research boat on 14-15 May 2009. The specific research objective was to gain an improved understanding of the role of direct groundwater discharge in delivery of excess nitrogen to the bay, which may have contributed to the development of low-oxygen conditions in waters of the bay and associated fish kills. Data collected in this survey included digital navigation information, continuous resistivity profiling (CRP) data, and point salinity measurements. The CRP method is a survey and data processing approach that is sensitive to differences in electrical properties of surface water and underlying porewater in sediments that have contrasting salinities. During the survey, Greenwich Bay salinity was approximately 27 ppm, so surface water would be expected to have low electrical resistivity (high conductivity), and any areas of active groundwater discharge from less salty aquifer sources would yield relatively higher resistivity values. This survey is identified as field activity 09021 (also referenced as 2009-021-FA) by the U.S. Geological Survey, Woods Hole, Massachusetts, and additional information is available from: https://cmgds.marine.usgs.gov/fan_info.php?fan=2009-021-FA.
  1. How might this data set be cited?
    Cross, VeeAnn A., 2018, Point shapefile of processed continuous resistivity profiling data below the sediment water interface collected in Greenwich Bay, Rhode Island, on May 15, 2009, on U.S. Geological Survey Field Activity 2009-021-FA (Geographic, WGS84): data release DOI:10.5066/F7DR2TSX, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Bratton, John F., and Cross, VeeAnn A., 2018, Continuous Resistivity Profiling Data and Associated Data from Greenwich Bay, Rhode Island collected in 2009, U.S. Geological Survey Field Activity 2009-021-FA: data release DOI:10.5066/F7DR2TSX, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Bratton, J.F., and Cross, V.A., 2018, Continuous resistivity profiling data and associated data from Greenwich Bay, Rhode Island collected in 2009, U.S. Geological Survey Field Activity 2009-021-FA: U.S. Geological Survey data release, https://doi.org/10.5066/F7DR2TSX.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -71.447056
    East_Bounding_Coordinate: -71.369674
    North_Bounding_Coordinate: 41.682943
    South_Bounding_Coordinate: 41.652150
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2009-021-FA/data/geophysics/shapefile/2009-021-FA_mrgmay15_resbsed.jpg (JPEG)
    Browse graphic of the CRP point shapefile data for May 15, 2009.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 15-May-2009
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Entity point (577229)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    mrgmay15_resbsed
    Esri point shapefile (Source: Esri)
    FID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    Id
    An automatically generated numeric value. (Source: VACExtras v. 2.05)
    Range of values
    Minimum:0
    Maximum:0
    line
    The alphanumeric name corresponding to the prefix of the GPS filename. This name reflects the name assigned to the line of data acquisition and incorporates modifiers (part1, part2) to reflect modification of the GPS file if the GPS file was split into more than one part. (Source: U.S. Geological Survey) Character set.
    dist
    Distance along line in meters. Originally calculated by the AGI processing software and assumed to be based on the UTM projection appropriate for the area (UTM, Zone 19). (Source: Processing software calculated.)
    Range of values
    Minimum:2
    Maximum:4592.6
    Units:meters
    longitude
    Longitude position of the point (decimal degrees, WGS84) (Source: Processing software calculated (VACExtras - convert resistivity to shapefile).)
    Range of values
    Minimum:-71.447056
    Maximum:-71.369674
    Units:decimal degrees
    latitude
    Latitude position of the point (decimal degrees, WGS84) (Source: Processing software calculated (VACExtras - convert resistivity to shapefile).)
    Range of values
    Minimum:41.65215
    Maximum:41.682943
    Units:decimal degrees
    utmx
    Easting position of the point in meters (UTM, Zone 19, WGS84) (Source: Processing software calculated (VACExtras - convert resistivity to shapefile).)
    Range of values
    Minimum:296319.5
    Maximum:302701.4
    Units:meters
    utmy
    Northing position of the point in meters (UTM, Zone 19, WGS84) (Source: Processing software calculated (VACExtras - convert resistivity to shapefile).)
    Range of values
    Minimum:4613962.5
    Maximum:4617367.7
    Units:meters
    depth
    Depth (meters) of the resistivity value below the water surface. This value is not corrected for tides or transducer draft. (Source: Acquisition software derived.)
    Range of values
    Minimum:-24.64
    Maximum:-0.9
    Units:meters
    dep_b_sed
    Depth (meters) of the resistivity value below the sediment/water interface. (Source: Processing software derived (MATLAB - justbelowsed.m).)
    Range of values
    Minimum:-23.74
    Maximum:0
    Units:meters
    resvalue
    Resistivity value of the data point in ohm-m. (Source: Processing software calculated (AGI EarthImager).)
    Range of values
    Minimum:0.1
    Maximum:54.7878
    Units:ohm-m
    reslogval
    Log(10) of the resistivity value. (Source: Processing software calculated (MATLAB justbelowsed.m).)
    Range of values
    Minimum:-1
    Maximum:1.738684
    Units:Log(10) of ohm-m
    Entity_and_Attribute_Overview:
    The data in the shapefile is also available in a CSV format. The FID and Shape attributes are omitted from the CSV file, but all the other attributes (attribute lables are in the first row of the CSV file) and data are included in the CSV file.
    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)
    • VeeAnn A. Cross
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

Why was the data set created?

The purpose of this shapefile is to release all the processed continuous resistivity profile data that occurs at the sediment water interface or below collected in Greenwich Bay, Rhode Island on May 15, 2009. These data were processed with a single water resistivity value.

How was the data set created?

  1. From what previous works were the data drawn?
    CRP data (source 1 of 1)
    Bratton, John F., 2015, Raw CRP data.

    Type_of_Source_Media: disk
    Source_Contribution:
    The continuous resistivity profile (CRP) system used on this cruise was an AGI SuperSting marine system described at the website: www.agiusa.com/marinesystem.shtml. Two streamer systems were used during this field activity - a 50-m streamer and a 100-m streamer. The 50-m streamer has an 11 electrode array with electrodes spaced 5 meters apart. The 100-m streamer has an 11 electrode array with electrodes spaced 10 meters apart. In both cases the source electrodes are graphite, while the receiver electrodes are stainless steel. A dipole-dipole configuration was used for the data collection in which two fixed current electrodes are assigned with the measurement of voltage potential between electrode pairs in the remaining electrodes. The maximum depth below the water surface the streamer can reach is approximately 1/4 the streamer length. So for the 50-m streamer, maximum depth is about 12.5 meters while the 100-m streamer maximum depth is about 25 meters. Each line of data acquisition records several files. The two files necessary for processing are the *.stg and the *.gps file. The STG file contains the resistivity data, while the GPS file contains the navigation information. The navigation system used in concert with the CRP system is a Lowrance LMS-480M with an LGC-2000 GPS antenna and a 200 kHz fathometer transducer. The antenna and fathometer transducer were mounted on the starboard side of the boat. The streamer tow point was on the port side aft. The layback offset between the navigation antenna and the first electrode was 16.5 meters. This layback offset was not accounted for during data acquisition, so was entered during processing of the data. The approximately 2.5 m lateral offset between the streamer tow point and the navigation antenna is not accounted for. The Lowrance transducer also contains a temperature sensor that records temperature in degrees Celsius. For depth measurements, Lowrance indicates the speed of sound used by the system is 4800 feet/second, but depths are recorded in meters. Both the temperature and depth information are recorded in the logged GPS file. The CRP system images the subsurface electrical properties of an estuarine, riverine or lacustrine environment. Resistivity differences can be attributed to subsurface geology (conductive vs less conductive layers) and hydrogeologic conditions with fresh water exhibiting high resistivity and saline conditions showing low resistivity.
  2. How were the data generated, processed, and modified?
    Date: 2009 (process 1 of 6)
    One of the resulting files from processing resistivity data with AGI's EarthImager software is an XYZ file. This XYZ file has three columns of information: distance along line (meters), resistivity reading depth (meters), resistivity value (ohm-m). One of the resulting files from linearization of the raw STG resistivity data is a DEP file. The DEP file has four columns of information: distance along line (meters), water depth (meters), latitude, longitude. This DEP file is dependent on the presence of bathymetry data in the originally recorded GPS file. This DEP file is used in the EarthImager processing and is carried over to the processing output. The MATLAB script justbelowsed.m combines these two data files (these files are available from this data release) such that the output is only the resistivity values that fall at or below the sediment water interface. This script was written by the USGS in Woods Hole, MA. In order to have a value at the sediment water interface, the software usually has to interpolate values. The version of MATLAB used for these data was MATLAB 7.5.0.342 (R2007b). An example of the script usage in MATLAB is: justbelowsed('L10F1_lin_AllInvRes.xyz','L10F1_lin_wres.dep'). The output is: L10F1_lin_AllInvRes_jbsed.xyz. This resulting XYZ file has 5 columns of information: distance along line (meters); depth below water surface (meters); depth below sediment/water interface (meters); resistivity value (ohm-m); log(10) resistivity value. This process step and all subsequent process steps were performed by the same person - VeeAnn A. Cross. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • *.dep
    • *.xyz
    Data sources produced in this process:
    • *jbsed.xyz
    Date: 2009 (process 2 of 6)
    Using ArcMap 9.2 and VACExtras v 2.05 (extension developed by the USGS in Woods Hole) these XYZ files are converted to shapefiles. The tool in VACExtras to do this is "convert resistivity to shapefile". This tool requires the data frame be in a UTM projection, the active layer in the data frame needs to be a polyline shapefile with one record selected (the polyline navigation file) and the user is prompted for the file from justbelowsed.m. The program uses the distance along value to find an actual latitude and longitude. The software assumes the datum of the data layer and the data frame projection are the same. The conversion of the Easting and Northing locations to latitudes and longitudes is done by the tool. The result is a point shapefile with 11 columns of information. The Id attribute is automatically generated upon creation of a shapefile, the "line" attribute is the line name as indicated within the polyline shapefile that the program prompts the user for, "dist" is the distance along attribute carried over from the MATLAB file, the attributes of location information (latitude, longitude, utmx, utmy) are calculated by the tool, the attributes depth, dep_b_sed, resvalue, and reslogval are carried over from the MATLAB file. The Entity and Attribute section further describes these attributes and their units. An individual point shapefile is generated for each CRP polyline. Data sources used in this process:
    • may15_09_gps_spl_lns.shp
    • *jbsed.xyz files from this day
    Data sources produced in this process:
    • *jbsed.shp
    Date: 2009 (process 3 of 6)
    With all the individual point shapefiles from May 15, 2009 in ArcMap 9.2, ArcToolbox - Data management Tools - General - Merge was used to combine the individual files into a single shapefile. The input was all the individual point shapefiles, with the output being mrgmay15_resbsed.shp. The field mapping was left at the defaults as all the input shapefiles have the same attributes. Data sources used in this process:
    • *jbsed.shp
    Data sources produced in this process:
    • mrgmay15_resbsed.shp
    Date: 2015 (process 4 of 6)
    Filename was changed to include the field activity number for publication purposes. Data sources used in this process:
    • mrgmay15_resbsed.shp
    Data sources produced in this process:
    • FA-2009-021_mrgmay15_resbsed.shp
    Date: 12-Apr-2018 (process 5 of 6)
    The point shapefile was exported to a CSV file. This was done in ArcGIS 10.3.1 using XToolsPro v. 12.0. Within XTools - Table operations - Export Table to File. Filename was set to 2009-021-FA_mrgmay15_resbsed.csv, all fields except FID were selected for export, and the option of comma separated values was chosen. This process was performed in order to provide the data in an open data format.
    Date: 08-Sep-2020 (process 6 of 6)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@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?
  2. How accurate are the geographic locations?
    The navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located 1.5 meters forward of the resistivity streamer tow point and directly above the fathometer transducer. The GPS is assumed to be accurate to within 10 meters.
  3. How accurate are the heights or depths?
    All bathymetry values were acquired by the 200 kHz Lowrance fathometer. The fathometer was mounted on the starboard side of the University of Rhode Island pontoon boat, directly below the GPS antenna. The Lowrance manufacturer indicates the speed of sound used by the system to calculate depth is 4800 feet/second. The depth values are not corrected for the approximately 0.2 m transducer draft. All depth values are assumed to be accurate to within 1 meter.
  4. Where are the gaps in the data? What is missing?
    All of the processed CRP data acquired May 15, 2009 are incorporated into this shapefile.
  5. How consistent are the relationships among the observations, including topology?
    Each file was looked at individually, but the files as a collection were handled in the same manner. All files on May 15, 2009 were collected with a 100-m resistivity streamer. The command file (*.cmd) used for data acquisition has a 1 meter electrode spacing. A scaling factor of 2 was erroneously applied during data acquisition. Since this date of data acquisition used the 100-m streamer, the scaling factor of 10 should have been used, but wasn't. This problem was resolved during the processing of the data by applying an additional scaling factor of 5.

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:
The public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
  2. What's the catalog number I need to order this data set? The FA-2009-021-FA_mrgmay15_resbsed.zip file contains the FA-2009-021_mrgmay15_resbsed shapefile and its components, the data in CSV format (2009-021-FA_mrgmay15_resbsed.csv), a browse graphic (2009-021-FA_mrgmay15_resbsed.jpg), and the FGDC CSDGM metadata in the following formats: XML, HTML, and text.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    The user must be capable of extracting the data from a zip file and reading the shapefile format. This shapefile filename starts with a number and has dashes in it. This filename may not work with some geoprocessing or ArcPy scripts and may need to be renamed.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/field_activities/2009_021_fa/2009-021-FA_mrgmay15_resbsed_meta.faq.html>
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