Continuous Resistivity Profiling, Electrical Resistivity Tomography and Hydrologic Data Collected in 2017 from Indian River Lagoon, Florida

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Frequently anticipated questions:

What does this data set describe?

Title:
Continuous Resistivity Profiling, Electrical Resistivity Tomography and Hydrologic Data Collected in 2017 from Indian River Lagoon, Florida
Abstract:
Extending 200 kilometers (km) along the Atlantic Coast of Central Florida, Indian River Lagoon (IRL) is one of the most biologically diverse estuarine systems in the continental United States. The lagoon is characterized by shallow, brackish waters and a width that varies between 0.5 and 9.0 km; there is significant human development along both shores. Scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center used continuous resistivity profiling (CRP, a towed electronic array) measurements, electrical resistivity tomography (ERT), and basic physical water column properties (for example, depth and temperature) to investigate submarine groundwater discharge at two locations, Eau Gallie North and Riverwalk Park, along the western shore of IRL. Eau Gallie North is near the central section of IRL and Riverwalk Park is approximately 20 km north of the Eau Gallie site. At each CRP study site, an 11-electrode marine resistivity array was towed over seven north–south shore parallel transects (EA–EG and RA–RG, respectively), situated between 75–1000 meters offshore, and approximately 1.5 km in length. Each transect was mapped three times in an alternating north–south direction to account for data collected by the concurrently-operating radon mapping system (Everhart and others, 2018). Repeat streaming resistivity surveys were collected bimonthly along these same tracklines, between March and November 2017, to determine seasonal and temporal variability. Since resistivity is a function of both geology and salinity, it is assumed that temporal shifts will reflect salinity changes, as the underlying geology will be presumed to remain constant. ERT study areas consisted of land- and shallow water-based surveys, where [DC] electrical current was injected into the ground via two current electrodes and received by nine potential electrodes. Electrode positions for both sites were recorded along six transects (T01-T06) and are provided in this data release as supplemental information (please see the ERT location map files included in, ERT_survey_maps.zip).
Supplemental_Information:
To ensure USGS-St. Petersburg data management protocols were followed, each survey was assigned the following USGS Field Activity Numbers (FAN): 2017-313-FA (March/April 2017, Project ID 17SGD02), 2017-328-FA (May/June 2017, Project ID 17SGD03), 2017-334-FA (July/August 2017, Project ID 17SGD04) and 2017-342-FA (September/November 2017, Project ID 17SGD05). Additional survey and data details are available from the U.S. Geological Survey Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/.
  1. How might this data set be cited?
    Forde, Arnell S., Smith, Christopher G., Zaremba, Nicholas J., and McBride, Elsie C., 20180919, Continuous Resistivity Profiling, Electrical Resistivity Tomography and Hydrologic Data Collected in 2017 from Indian River Lagoon, Florida: U.S. Geological Survey Data Release doi:10.5066/F7V40TFH, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -80.687959
    East_Bounding_Coordinate: -80.606936
    North_Bounding_Coordinate: 28.275933
    South_Bounding_Coordinate: 28.108010
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 25-Sep-2017
    Ending_Date: 07-Nov-2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Multimedia presentation
  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):
      • String (14)
    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 0.0197951485. Longitudes are given to the nearest 0.0223281105. 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 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    CRP_Tracklines_IRL.shp, IRL_tracklines.kmz
    These geospatial, line vector data files show the locations of continuous resistivity profiling survey tracklines collected from two study sites (Eau Gallie North and River Walk Park) along Indian River Lagoon, Florida in 2017. GIS files are provided in Esri shapefile (.shp) and Keyhole Markup Language (.kml) formats. Data are accessible from the folder named, “GIS”, which is included in resistivity_CRP.zip. (Source: USGS)
    FID
    Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry (Source: Esri) Geometry type defining the features.
    Name
    CRP trackline name (Source: USGS) CRP data were collected along 14 shore-parallel lines (EA-EG and RA-RG); line EA was not run until July 2017, due to low water conditions.
    resistivity_CRP.zip, resistivity_ERT.zip
    The folders (2017-313-FA, 2017-328-FA, 2017-334-FA, and 2017-342-FA) included in resistivity_CRP.zip contain the raw CRP resistivity, location and hydrologic parameter data collected from Indian River Lagoon, FL, March—October, 2017, in ASCII (comma-separated values) format. The Supersting (.stg) and Lowrance (.gps) data files are natively output from their respective system without column header labels. Each GPS file includes information related to time, date, location, water depth and temperature. Resistivity data files recorded: date, time, voltage, apparent resistivity, electrode position, etc. In addition to the .stg files, the ERT data also include .crs, .cmd and .uwt data files. (Source: USGS)
    UWTdata.xlsx (EGN), UWTdata_EGN.csv
    This file contains under-water terrain (UWT) files, for the EGN site, that were used in the inversion of the ERT data. (Source: USGS)
    Transect ID
    Transect Identifier (Source: UGSS)
    Range of values
    Minimum:1
    Maximum:6
    Electrode No.
    Electrode number (1 is farthest from the SuperSting, 28 closest) (Source: USGS)
    Range of values
    Minimum:1
    Maximum:28
    Easting (meters, UTM NAD83)
    Projected X (Easting, in meters) global positioning system data in Zone 17 of the Universal Transverse Mercator system, North American Datum of 1983. (Source: USGS)
    Range of values
    Minimum:537296.5598
    Maximum:537363.7634
    Northing (meters, UTM NAD83)
    Projected Y (Northing, in meters) global positioning system data in Zone 17 of the Universal Transverse Mercator system, North American Datum of 1983. (Source: USGS)
    Range of values
    Minimum:3110005.2
    Maximum:3110116.624
    Water_Depth_m (May-2017)
    Water Depth (in meters) measured during May 2017 survey. (Source: USGS)
    Range of values
    Minimum:0.11
    Maximum:0.53
    Water_Depth_m (Sep-2017)
    Water Depth (in meters) measured during September 2017 survey. (Source: USGS)
    Range of values
    Minimum:0.48
    Maximum:1.04
    UWTdata.xlsx (RWP), UWTdata_RWP.csv
    This file contains UWT files, for the RWP site, that were used in the inversion of the ERT data. (Source: USGS)
    Transect ID
    Transect Identifier (Source: USGS)
    Range of values
    Minimum:1
    Maximum:6
    Electrode No.
    Electrode number (1 is farthest from the SuperSting, 28 closest) (Source: USGS)
    Range of values
    Minimum:1
    Maximum:28
    Easting (meters, UTM NAD83)
    Projected X (Easting, in meters) global positioning system data in Zone 17 of the Universal Transverse Mercator system, North American Datum of 1983. (Source: USGS)
    Range of values
    Minimum:530657.6158
    Maximum:530715.7478
    Northing (meters, UTM NAD83)
    Projected Y (Northing, in meters) global positioning system data in Zone 17 of the Universal Transverse Mercator system, North American Datum of 1983. (Source: USGS)
    Range of values
    Minimum:3126902.16
    Maximum:3127025.0549
    Water_Depth_m (May-2017)
    Water Depth (in meters) measured during May 2017 survey. (Source: USGS)
    Range of values
    Minimum:0.08
    Maximum:1.36
    Water_Depth_m (Nov-2017)
    Water Depth (in meters) measured during November 2017 survey. (Source: USGS)
    Range of values
    Minimum:0.15
    Maximum:1.55
    Entity_and_Attribute_Overview:
    The detailed attribute descriptions for the location, resistivity, contact resistance, and under-water terrain files are provided in the included data dictionaries (DataDictionary_GPS.pdf, DataDictionary_STG.pdf, DataDictionary_CRS.pdf, and DataDictionary_UWT.pdf, respectively), the metadata are not complete without these .pdf files.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information was generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Arnell S. Forde
    • Christopher G. Smith
    • Nicholas J. Zaremba
    • Elsie C. McBride
  2. Who also contributed to the data set?
    Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data. The authors wish to thank Cheyenne Everhart, Paul Nelson, and Kyle Kelso for their assistance in data collection. This document was improved by the scientific and metadata reviews of Cheyenne Everhart and Chelsea Stalk (Cherokee Nation Technologies).
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Arnell S. Forde
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    aforde@usgs.gov

Why was the data set created?

This data release serves as an archive of resistivity, water column, and global positioning system (GPS) data collected from Indian River Lagoon, FL, from March through November of 2017. Resistivity data collected in December 2016 and January 2017 are available in a previously published data release (McCloskey and others, 2017).

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: 2017 (process 1 of 7)
    Planned CRP survey trackline files for each study site were created with Google Earth Pro 7.3.0.3832 software and saved in Keyhole Markup Language (KML) format. The KML file was later imported into ArcMap 10.3.1 for additional editing and exported in Esri shapefile format (.shp). The final GIS files, CRP_Tracklines_IRL.shp and IRL_tracklines.kmz, are included in the data download file, resistivity_CRT.zip (please see the "GIS" folder).
    Date: 2017 (process 2 of 7)
    CRP Acquisition - Between March and October 2017, a USGS barge traveled at no more than 1-1.5 knots to map marine resistivity and hydrologic parameters (water depth and temperature) along 14 shore-parallel, latitudinal transects located approximately 75, 125, 200, 350, 500, 750 and 1000 m off the western edge of Indian River Lagoon, FL. A boat-mounted Lowrance HDS-5 dual frequency 50/200 kHz transducer recorded trackline information including time, position, temperature and water depth data at the Eau Gallie North (tracklines EA-EG) and Riverwalk Park (lines RA-RG) study sites. The CRP cable consists of an array of electrodes, with two current (transmitting) electrodes and a number of potential (receiving) electrodes, producing a file (.stg) that records apparent resistivity between the matched pairs of current and potential electrodes. Spacing between the receiving electrodes is either 5 or 10 m, depending upon the connection ("pigtail") used to couple the cable to the recording device, the AGI Supersting R8/IP. Data consists of vertical profiles of electrical resistance extending from ~10-25 m below the seafloor, with the 10 m electrode spacing resulting in deeper penetration. The closest transect to shore at Eau Gallie North, EA, was not run until July 2017, due to low water conditions. Water depth, water temperature and geographic data were collected by a Lowrance boat-mounted GPS system, which was temporally synchronized with the resistivity system to produce a National Marine Electronics Association (NMEA) 0813 file (.gps). The GPS-enabled functions were: Recommended Minimum Navigation Information (RMC), Depth of Water (DPT), and Mean Temperature of Water (MTW). Person who carried out this activity:
    U.S. Geological Survey
    Attn: Christopher G. Smith
    Research Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cgsmith@usgs.gov
    Date: 2017 (process 3 of 7)
    CRP Initial Processing - The raw .stg (apparent resistivity) and .gps (NMEA 0813) files were uploaded into the Marine Log Manger (registered trademark, AGI) version 1.3.4.217 module included with the SuperSting R8/IP (registered trademark, AGI) software package. The two data files were combined, linearized and clipped to remove extraneous sections (for example, turns at the end of survey tracklines) and/or unreasonable data points. This resulted in geographical coordinates for all the CRP measurements, water temperature and depth values, thereby, creating a spatial representation of the sub-surface's apparent resistivity along each track. The raw data files can be accessed from the data download file, resistivity_CRP.zip Person who carried out this activity:
    U.S. Geological Survey
    Attn: Arnell S. Forde
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    aforde@usgs.gov
    Date: 2017 (process 4 of 7)
    ERT Acquisition for May and September/November-2017 Surveys - USGS personnel placed individual electrodes at a 2-m spacing just below the seabed for each transect (T01-T06). ERT surveys were carried out in a stationary mode such that electrodes were not moved during several different data acquisition designs, often referred to as geometric configurations. During each geometric configuration, electrodes remained stationary while the AGI SuperSting R8/IP modified which of the potential and current electrodes were used. The geometric configurations applied during these surveys were either dipole-dipole or dipole-gradient. The geometry of the current and potential electrodes used during each geometric configuration is provided in the generic command (.cmd) files dd28r.cmd (for dipole-dipole setup) and dg28f.cmd (dipole-gradient). During acquisition, the horizontal and vertical position (depth in meters) was determined using a RTK system and a graduated stadia rod with 0.005 m resolution. At both the Eau Gallie and Riverwalk Park field regions, surveys were conducted along six shore-parallel and/or shore-perpendicular transects as shown in the supplemental figures, EG_Electrode_GPS.jpg and RWP_Electrode_GPS.jpg (see, ERT_survey_maps.zip). Seafloor profiles were created following the template provided by AGI in the EarthImager v2.3.3 software manual and saved as under-water terrain (.uwt) files. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Christopher G. Smith
    Research Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cgsmith@usgs.gov
    Date: 2017 (process 5 of 7)
    ERT Initial Processing - The AGI SuperSting R8/IP produces several files for each data acquisition survey, including but not limited to, the raw .stg (apparent resistivity), .crs (contact resistance), and .cmd (a copy of the geometric configuration command file used but renamed for each data acquisition file). The .crs file was loaded into EarthImager 2D v2.3.3 and examined for large (greater than 2000 ohm per meter) contact resistance values for quality control. Once acceptable contact resistance was verified, the raw .stg lines were, as needed, reversed and/or shifted to produce consistent, geographically-oriented transects for final image presentation. Therefore, all images of shore-perpendicular transects are oriented west-to-east and shore-parallel transects are oriented north-to-south. The raw, reversed and/or shifted .stg and .uwt data files were then loaded into EartherImager 2D v2.3.3 to perform resistivity inversions based on software defaults <Conductive Earth Setting>, please see the EarthImager manual for details. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Christopher G. Smith
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cgsmith@usgs.gov
    Date: 2017 (process 6 of 7)
    Inversion Model Processing - Apparent resistivity values acquired in the field do not factor in differences in porewater salinity and sub-surface geology. To account for this during subsequent data analysis and interpretation, a two-dimensional (2D) inversion modeling software package was employed to help interpret the continuous resistivity profiling measurements and electrical tomography data. EarthImager 2D v2.3.3 was used to integrate the resistivity and hydrologic information. The EarthImager 2D system defaults, "CRP Saltwater" (used for CRP data) and "Conductive Earth Setting" (ERT) were adapted for processing their respective resistivity datasets. The final inversion model outputs include a three-panel figure where the top panel displays the raw resistivity data (measured), the middle panel shows the EarthImager 2D model created to best fit the raw data (calculated), and the bottom panel provides the modeled resistivity (inverted), which accounts for salinity and geologic parameters. The inverted resistivity profile images are included in the data release as supplemental information and can be accessed from the inversion_model_images.zip file. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Arnell S. Forde
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    aforde@usgs.gov
    Date: 13-Oct-2020 (process 7 of 7)
    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?
    Advanced Geosciences, Inc., 2006, The SuperSting with Swift automatic resistivity and IP system Instruction Manual.

    Online Links:

    McCloskey, Terrence A., Smith, Christopher G., Zaremba, Nick J., McBride, Elsie C., and Everhart, Cheyenne S., 20170420, Hydrological Data Concerning Submarine Groundwater Discharge Along the Western Margin of Indian River Lagoon, East-Central Florida-December 2016 and January 2017: U.S. Geological Survey Data Release doi:10.5066/F7PZ5725, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    Everhart, Cheyenne S., Nelson, Paul R., Smith, Christopher G., and Flint, Madison K., 20180227, Radon-222 and Water Column Data Related to Submarine Groundwater Discharge Along the Western Margin of Indian River Lagoon, Florida—September 2017 and November 2017: U.S. Geological Survey Data Release doi:10.5066/F76Q1WG4, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

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

  1. How well have the observations been checked?
    For the marine surveys, the GPS and CRP attribute values were determined by the accuracy of the boat-mounted Lowrance HDS-5 receiver and Advanced Geosciences, Inc. (AGI) SuperSting R8/IP, respectively. The manufacturer’s tolerance for the SuperSting is better than 1% of readings, in most cases (lab measurements). The SuperSting calculated and displayed a running estimate of measuring accuracy and field measurement accuracy depended on ground noise and terrain resistivity. Position data and ERT attribute values for the land surveys were determined by a Spectra Precision SP80 Global Navigation Satellite System (GNSS) receiver, using the Florida Department of Transportation real-time kinematic (RTK) network (http://www.fdot.gov/geospatial/FPRNProducts.shtm) and the AGI SuperSting R8/IP, respectively.
  2. How accurate are the geographic locations?
    The horizontal accuracy of the CRP sample locations was determined by the accuracy of the boat-mounted Lowrance HDS-5 GPS receiver used to record the positional data of the boat during the data collection process. Reoccupation of the sites showed that the positional accuracy for the Lowrance was approximately 1 m. The horizontal accuracy of the ERT electrode sample locations was determined by the accuracy of RTK rover system. Accuracy of the system is defined as 0.02 m and accuracy during reoccupation of locations visited during 2017-342-FA was determined to be better than 0.10 m.
  3. How accurate are the heights or depths?
    The only vertical measurements incorporated into the data files are the water column depth measurements, measured by the boat-mounted Lowrance HDS-5 transducer, with a resolution of 10 cm. Depths were measured from the transducer (which is approximately 35 cm below the water surface) down to the seafloor. For ERT data, vertical measurements are water depth measurements that are site and time specific and have been reported in the supplemental tables (UWTdata.xlsx, UWTdata_EGN.csv and UWTdata_RWP.csv) that are included in the data download file, resistivity_ERT.zip. Those data are tabulated with electrode and line identifiers. The accuracy of depth values is based on replicated measurements at the time of each survey and the precision is determined to be 0.03 m.
  4. Where are the gaps in the data? What is missing?
    This dataset contains the raw geographic, water column (depth and temperature) and resistivity data files produced by the boat-mounted Lowrance and Supersting (AGI) resistivity systems, during surveys conducted March—September 2017. Due to low water conditions, the shallowest trackline (Line EA) was not run until July 2017 (2017-334-FA). Data collection for 2017-342-FA was not completed during the initial survey dates (09/25/17-10/06/17); consequently, a second site visit occurred November 1-17, 2017. Line RWP719 was too short to process using an overlap of 162 data points as the complete profile length was only 223 so it was excluded from this data release. For ERT surveys, all electrodes were placed at locations determined via a RTK GPS system, during survey 2017-323-FA, and reoccupied during 2017-342-FA using the same RTK system set to navigate to the 2017-323-FA electrode locations.
  5. How consistent are the relationships among the observations, including topology?
    This dataset is from multiple field activities, all with consistent instrument calibrations. During 2017-313-FA data collection, the GPS offset was input into the SuperSting as -10 m; however, a -5 m scaling factor (5 m pigtail) was actually utilized resulting in erroneous distance values being applied to the electrode positions during acquisition. To correct this issue, the impacted .stg files were adjusted in Excel 2016 by applying a fixed offset to the affected lines. These corrected .stg files have been provided in this data release; the line naming convention for the preceding includes the original line name appended with "_adj" (for example, EGN7401E_adj.stg). In some cases, sparse or no water depth values were recorded to a .dep file, which manifested as a missing depth variable ($SDDPT) within the GPS file, so modified .gps files (*m.gps) were created during post-processing by extracting bathymetry values from an interpolated raster grid created by C. Smith. For ERT surveys, all electrode positions were set in the May-2017 survey (2017-328-FA) with a positional accuracy of 0.02 m based on manufacturer estimates. For the following surveys conducted in September and November (2017-342-FA), the electrodes were placed at the original May-2017 location within a 0.1 m precision based on the RTK navigation screen output.

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:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of the data in future products or derivative research. Users are advised to read the metadata record thoroughly to understand appropriate use and data limitations.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    Attn: Arnell S. Forde
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    aforde@usgs.gov
  2. What's the catalog number I need to order this data set? EGN*.stg, EGN*.gps, RWP*.stg, RWP*.gps, T0*.stg., T0*.cmd, T0*.crs, UWTdata_EGN.csv, UWTdata_RWP.csv, UWTdata.xls, CRP_Tracklines_IRL.shp, and IRL_tracklines.kmz
  3. What legal disclaimers am I supposed to read?
    This publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, 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 imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
U.S. Geological Survey
Attn: Arnell S. Forde
Geologist
600 4th Street South
St. Petersburg, FL
USA

727-502-8000 (voice)
aforde@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/IRL_resistivity_metadata.faq.html>
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