Point shapefile (100 shot interval) of navigation for chirp seismic data collected in the Indian River Bay, Delaware, on April 13, 2010, on U.S. Geological Survey Field Activity 2010-006-FA (IR_100SHOT_SORT.SHP, Geographic, WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
Point shapefile (100 shot interval) of navigation for chirp seismic data collected in the Indian River Bay, Delaware, on April 13, 2010, on U.S. Geological Survey Field Activity 2010-006-FA (IR_100SHOT_SORT.SHP, Geographic, WGS 84)
Abstract:
A geophysical survey to delineate the fresh-saline groundwater interface and associated sub-bottom sedimentary structures beneath Indian River Bay, Delaware, was carried out in April 2010. This included surveying at higher spatial resolution in the vicinity of a study site at Holts Landing, where intensive onshore and offshore studies were subsequently completed. The total length of continuous resistivity profiling (CRP) survey lines was 145 kilometers (km), with 36 km of chirp seismic lines surveyed around the perimeter of the bay. Medium-resolution CRP surveying was performed using a 50-meter streamer in a bay-wide grid. Results of the surveying and data inversion showed the presence of many buried paleochannels beneath Indian River Bay that generally extended perpendicular from the shoreline in areas of modern tributaries, tidal creeks, and marshes. An especially wide and deep paleochannel system was imaged in the southeastern part of the bay near White Creek. Many paleochannels also had high-resistivity anomalies corresponding to low-salinity groundwater plumes associated with them, likely due to the presence of fine-grained estuarine mud and peats in the channel fills that act as submarine confining units. Where present, these units allow plumes of low-salinity groundwater that was recharged onshore to move beyond the shoreline, creating a complex fresh-saline groundwater interface in the subsurface. The properties of this interface are important considerations in construction of accurate coastal groundwater flow models. These models are required to help predict how nutrient-rich groundwater, recharged in agricultural watersheds such as this one, makes its way into coastal bays and impacts surface water quality and estuarine ecosystems. For more information on the survey conducted for this project, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-006-FA.
  1. How might this data set be cited?
    Bratton, John F., and Cross, VeeAnn A., 2014, Point shapefile (100 shot interval) of navigation for chirp seismic data collected in the Indian River Bay, Delaware, on April 13, 2010, on U.S. Geological Survey Field Activity 2010-006-FA (IR_100SHOT_SORT.SHP, Geographic, WGS 84): Open-File Report 2011-1039, 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.

    Cross, V.A., Bratton, J.F., Michael, H.A., Kroeger, K.D., Green, A., and Bergeron, E., 2014, Continuous Resistivity Profiling and Seismic-Reflection Data Collected in April 2010 from Indian River Bay, Delaware: Open-File Report 2011-1039, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.202086
    East_Bounding_Coordinate: -75.062936
    North_Bounding_Coordinate: 38.618983
    South_Bounding_Coordinate: 38.569244
  3. What does it look like?
    https://pubs.usgs.gov/of/2011/1039/data/navigation/seismics/ir_100shot_sort.gif (GIF)
    Thumbnail GIF images showing the 100 shot point location of seismics collected in Indian River Bay. The coastline is included for spatial reference.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 13-Apr-2010
    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 (1086)
    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.
  7. How does the data set describe geographic features?
    ir_100shot_sort
    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.
    linename
    The unique identifier for each line of data acquistion. This is the prefix of the SEG-Y filename. (Source: U.S. Geological Survey) Character set.
    shot
    The seismic shot number associated with the navigation fix. (Source: Software generated.)
    Range of values
    Minimum:1
    Maximum:8966
    Units:shot
    Distance
    The distance that the point falls off the calibrated route polyline. Unsure of units as all values are zeros and the work was done in a geographic coordinate system. Of note, one point was manually moved (discussed in the process steps) and may not fall exactly on the line. This is shot 1500 on line l5f2. (Source: Esri linear Referencing - Locate Feature Along Routes tool)
    Range of values
    Minimum:0
    Maximum:0
    Units:unknown

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • John F. Bratton
    • 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
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

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

Why was the data set created?

The purpose of the data layer is to provide the 100 shot point navigation associated with the seismic-reflection profiles collected on U.S. Geological Survey Field Activity Number 2010-006-FA. This information helps correlate the seismic-reflection profiles with other features and data in the GIS. The 100 shot interval corresponds to tic marks on the seismic-reflection profile JPEG images.

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: 2010 (process 1 of 12)
    The seismic acquisition system used on this cruise was an EdgeTech 424 Chirp sub-bottom system with a 4 to 24 kHz pulse bandwidth and a 2 ms pulse. The system towfish was attached by a short line to a cleat on a 2 x 6 board that was clamped across the bow of the boat. The towfish was on the starboard side of the boat, approximately 0.5 meters below the water surface. The acquisition software used to record the data was Discover 3100 version 7.01. The data were recorded in the SEG-Y data format IBM floating point with navigation supplied by the Lowrance GPS system. The navigation was recorded in the header of the seismic data in an arc second format. The record length is 133 ms, with a sample interval of 23 micro-seconds and 5788 samples per trace. The fire-rate was between 4 and 6 shots per second. The GPS antenna was located above the tow position of the seismic transducer.
    Date: Jan-2011 (process 2 of 12)
    Using the calibrated polyline shapefile (ir_Routes_Calib available at https://pubs.usgs.gov/of/2011/1039/html/ofr2011-1039-catalog.html), hatches were added at the beginning and end of each line, as well as at 100 shot spacing. This was done in ArcMap 9.2 by opening the layer properties and selecting the Hatches tab. Create a hatch interval of 100 for the Hatch Class, then for Hatch Def(1) place a marker hatch every 1 hatch interval. From the Hatch Class Add a Hatch Definition - Add End Hatch Definition and set these to a marker Hatch. By displaying the labels for both Hatch Definitions, a quick comparison between the hatches and the unique shot navigation makes sure things are behaving as intended. Then turn the labels off. 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
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • ir_Routes_Calib.shp
    Data sources produced in this process:
    • ir_Routes_Calib.shp
    Date: Jan-2011 (process 3 of 12)
    Within ArcMap 9.2 - by going to Tools - Customize - Commands and scrolling down to the Category "Linear Referencing", the icon for the command "Convert Hatches to Graphics can be added to a toolbar. Once this is done, that tool can be used to convert the hatches to graphics. Data sources used in this process:
    • ir_Routes_Calib.shp
    Data sources produced in this process:
    • graphics
    Date: Jan-2011 (process 4 of 12)
    Convert these graphics to a shapefile using XTools Pro version 5.2. XTools Pro - Feature Conversions - Convert Graphics to Shapes. Source graphics layer: default, graphics element type: points. Output: ir_100shot_graphics.shp Data sources used in this process:
    • graphics
    Data sources produced in this process:
    • ir_100shot_graphics.shp
    Date: Jan-2011 (process 5 of 12)
    Use ArcMap 9.2 - ArcToolbox - Linear Referencing Tools - Locate Features Along Route. Use the following parameters: input - ir_100shot_graphics; input route features - ir_Routes_Calib; route identifier field - linename; search radius - 5 meters; output event table - ir_100shot_LocateFeatures.dbf. Output event table properties: route identifier field - linename; event type - point (default); measure field - shot. Left rest of options at default (all checked). Data sources used in this process:
    • ir_Routes_Calib.shp
    Data sources produced in this process:
    • ir_100shot_LocateFeatures.dbf
    Date: Jan-2011 (process 6 of 12)
    Use ArcMap 9.2 - ArcToolbox - Linear Referencing Tools - Make route Event Layer to create an event feature using the following parameters: input route features - ir_Routes_Calib; route identifier field - linename; input event table - ir_100shot_LocateFeatures; route identifier field - linename; event type - point; measure field - shot. Rest of the option left at default values. Data sources used in this process:
    • ir_Routes_Calib.shp
    • ir_100shot_LocateFeatures.dbf
    Data sources produced in this process:
    • ir_100shot_LocateFeatures Events
    Date: Jan-2011 (process 7 of 12)
    Convert the event layer to a shapefile in ArcMap 9.2 by exporting the data (right mouse click on event layer, Data, Export Data). Output: ir_shot100tmp.shp Data sources used in this process:
    • ir_100shot_LocateFeatures Events
    Data sources produced in this process:
    • ir_shot100tmp.shp
    Date: Jan-2011 (process 8 of 12)
    Within ArcMap 9.2 use VAC Extras version 2.1 (an extension written by the USGS in Woods Hole) to sort the shapefile. VAC Extras - FeatConv - Table Sort with the shot file sorted based on linename and shot. Linename was set as the primary sort field, ascending order. Shot was set as the secondary sort field - ascending order. Output to ir_100shot_sort.shp. Data sources used in this process:
    • ir_shot100tmp.shp
    Data sources produced in this process:
    • ir_100shot_sort.shp
    Date: Jan-2011 (process 9 of 12)
    Because there are instances where the seismic acquisition automatically switched files, there are instance where the end shot of one line is in the same location as the start shot of the next line. An example of this are the lines l1f2 and l1f2.001. This issue leads to a duplicate shot #1 at these boundaries. The first shot #1 as it appears in the table should reflect the linename of the previous line, and it's ending shot number. For example, the first occurrence of l1f2.001 had the linename edited to be l1f2, and the shot value changed from 1 to 8959. The ending shot number was determined by displaying the hatch labels on the calibrated polyline generated earlier in the process steps. On line l5f2 there are 3 points with the shot number 1500. The problem with this line is they did a loop. Because the line crossed itself, the confusion as to the location of shot 1500 arose. Using the editor, I deleted the 2 shot 1500's that don't belong, and manually moved the location of the remaining shot 1500 to correspond to the calibrated polyline position of that shot number combined with the information from the shapefile containing all the original shot point navigation. Users will have to be careful if using the calibrated shot measures for this looped line in the loop area. Data sources used in this process:
    • ir_100shot_sort.shp
    Data sources produced in this process:
    • ir_100shot_sort.shp
    Date: 02-Oct-2017 (process 10 of 12)
    Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Attempted to modify http to https where appropriate. Moved the minimal source information provided to make it the first process step. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. 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
    Date: 20-Jul-2018 (process 11 of 12)
    USGS Thesaurus keywords added to the keyword section. 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
    Date: 08-Sep-2020 (process 12 of 12)
    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 above the seismic towfish tow point. The system towfish was attached by a short line to a cleat on a 2 x 6 board that was clamped across the bow of the boat. The towfish was on the starboard side of the boat, approximately 0.5 meters below the water surface. GPS data are assumed to be accurate within 10 meters on this survey.
  3. How accurate are the heights or depths?
    Although bathymetry was not recorded directly with this system, bathymetry can be derived by tracing the seafloor reflector in the seismic-reflection profiles. The seismic towfish was attached to a cleat by a short line on the starboard side of the boat. The transducer draft was approximately 0.5 m below the water surface. The draft offset was not included in the data acquisition.
  4. Where are the gaps in the data? What is missing?
    This shapefile represents the 100 shot interval navigation for all the seismic lines collected on this cruise.
  5. How consistent are the relationships among the observations, including topology?
    These points were visually checked to make sure they were viable fixes.

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
    Woods Hole Coastal and Marine Science Center
    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? Downloadable Data
  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?
    This zip file contains data available in Esri point shapefile format. The user must have software capable of uncompressing the zip file and reading/displaying the shapefile.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
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/open_file_report/ofr2011-1039/ir_100shot_sortmeta.faq.html>
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