Processed Continuous Resistivity Profile Data Collected in the Potomac River/Chesapeake Bay on Sept. 8, 2006

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: John F. Bratton
Originator: VeeAnn A. Cross
Publication_Date: 2010
Title:
Processed Continuous Resistivity Profile Data Collected in the Potomac River/Chesapeake Bay on Sept. 8, 2006
Series_Information:
Series_Name: Open-File Report
Issue_Identification: 2009-1151
Publication_Information:
Publication_Place: Woods Hole Coastal and Marine Science Center, Woods Hole, MA
Publisher: U.S. Geological Survey, Coastal and Marine Geology Program
Online_Linkage:
<https://pubs.usgs.gov/of/2009/1151/data/resistivity/proc_resis/sept8_proc.zip>
Online_Linkage: <https://pubs.usgs.gov/of/2009/1151/html/catalog.html>
Larger_Work_Citation:
Citation_Information:
Originator: VeeAnn A. Cross
Originator: David S. Foster
Originator: John F. Bratton
Publication_Date: 2010
Title:
Continuous Resistivity Profiling and Seismic-Reflection Data Collected in 2006 from the Potomac River Estuary, Virginia and Maryland
Series_Information:
Series_Name: Open-File Report
Issue_Identification: 2009-1151
Publication_Information:
Publication_Place: Woods Hole Coastal and Marine Science Center, Woods Hole, MA
Publisher: U.S. Geological Survey, Coastal and Marine Geology Program
Online_Linkage: <https://pubs.usgs.gov/of/2009/1151/>
Description:
Abstract:
In order to test hypotheses about groundwater flow under and into Chesapeake Bay, geophysical surveys were conducted by U.S. Geological Survey (USGS) scientists on Chesapeake Bay and the Potomac River Estuary in September 2006. Chesapeake Bay resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge, which are contributing to eutrophication. The USGS has performed many related studies in recent years to provide managers with information necessary to make informed decisions about this issue. The research carried out as part of the study described here was designed to help refine nutrient budgets for Chesapeake Bay by characterizing submarine groundwater flow and discharge of groundwater beneath part of the mainstem and a major tributary, the Potomac River Estuary.
Purpose:
To provide the processed continuous resistivity profile (CRP) data collected on this date by the AGI SuperSting system.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 20060908
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -76.856267
East_Bounding_Coordinate: -76.362700
North_Bounding_Coordinate: 38.004733
South_Bounding_Coordinate: 38.231150
Keywords:
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Coastal and Marine Geology Program
Theme_Keyword: CMGP
Theme_Keyword: Woods Hole Coastal and Marine Science Center
Theme_Keyword: WHCMSC
Theme_Keyword: Field Activity Serial Number 06018
Theme_Keyword: Info Bank ID K-1-06-CH
Theme_Keyword: navigation
Theme_Keyword: bathymetry
Theme_Keyword: Continuous Resistivity Profiling
Theme_Keyword: CRP
Theme_Keyword: R/V Kerhin
Theme_Keyword: Lowrance GPS
Theme_Keyword: AGI SuperSting
Theme_Keyword: processed data
Theme_Keyword: groundwater
Theme_Keyword: submarine groundwater
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: elevation
Theme_Keyword: inlandWaters
Theme_Keyword: location
Theme_Keyword: oceans
Theme_Keyword: oceans and estuaries
Theme_Keyword: oceans and coastal
Theme_Keyword: geoscientificInformation
Place:
Place_Keyword_Thesaurus: General
Place_Keyword: North America
Place_Keyword: North Atlantic
Place_Keyword: United States
Place_Keyword: Virginia
Place_Keyword: Potomac River Estuary
Place_Keyword: Chesapeake Bay
Place_Keyword: Dennis Point Marina
Place_Keyword: Solomons, Maryland
Place_Keyword: Maryland
Place_Keyword: Patuxent River
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.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: John F. Bratton
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2254
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: jbratton@usgs.gov
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.1850
Cross_Reference:
Citation_Information:
Originator: Advanced Geosciences, Inc.
Publication_Date: 2005
Title:
Instruction Manual for EarthImager 2D, version 1.9.0, Resistivity and IP inversion software
Online_Linkage: <http://www.agiusa.com/>
Cross_Reference:
Citation_Information:
Originator: Advanced Geosciences, Inc.
Publication_Date: 2003
Title:
Instruction Manual for the Marine Log Manager Module of the Administrator for SuperSting Software, Release 1.3.7
Online_Linkage: <http://www.agiusa.com/>
Data_Quality_Information:
Logical_Consistency_Report: All the data files were checked and handled in the same manner.
Completeness_Report:
All usable data collected on this day was processed. The processed files are included in this dataset.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
The primary navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located 7.9 meters forward of the anchor point for the resistivity streamer, and approximately 3 meters forward of the fathometer transducer. These offsets were not entered into the GPS system. Additionally, because of navigation and fathometers issues, periodically the ship's navigation system was used to supplement these data. The ship had a Differential GPS (DGPS) system with the antenna placed in the same location as the Lowrance antenna. The fathometer was located (hull-mounted) roughly directly below the antenna, so no horizontal offset. Because of the mixture of systems, the accuracy is on the order of 20 meters.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
On this day the bathymetric values were collected by the Lowrance fathometer. This fathometer was mounted mid-ship on the starboard side of the boat. The Lowrance manufacturer indicates the speed of sound used by the system to convert to depths is 4800 feet/second. All values are assumed to be accurate to within 1 meter.
Lineage:
Source_Information:
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. The particular system used for this acquisition was a 100-m streamer with an 11 electrode array with electrodes spaced 10 meters apart. 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. 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 transducer also contains a temperature sensor which was not working on Julian Day 249. Lowrance indicates the speed of sound used by the system is 4800 feet/second. On the first day of data collection (Julian Day 249, Sept. 6, 2006) the Lowrance transducer was side-mounted mid-ship on the port side of the boat. The remainder of the cruise the transducer was side-mounted mid-ship of the starboard side of the boat. 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.
Process_Step:
Process_Description:
Once the navigation and raw data were assessed to be okay, the actual processing of the data could start. The resistivity data were merged with the navigation data and linearized using AGI's Marine Log Manager software. (Note that the Marine Log Manager version is different than the software version of the AGISSAdmin software of which it is a part - although shipped together, the software is developed separately). The version of Marine Log Manager used was AGI SSAdmin MLM v 1.3.4. The GPS offset was set to 7.9 meters to account for the difference between the navigation antenna and the resistivity cable tow point. The lines processed on this day are L20F1, L21f1, L22F1, L23F1, L24F1, L25F1, L25F2, L26F1. These line names are what the * refers to in the source used and source produced citations. This process step and all subsequent process steps were performed by the same person - VeeAnn A. Cross.
Source_Used_Citation_Abbreviation: *.gps
Source_Used_Citation_Abbreviation: *.stg
Process_Date: 2006
Source_Produced_Citation_Abbreviation: *_lin.stg
Source_Produced_Citation_Abbreviation: *_lin.dep
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
The DEP file was checked for anomalous bathymetry values, or duplicated distance along values, and those lines in the file were deleted.
Process_Date: 2006
Process_Step:
Process_Description:
EarthImager software does not require that a default resistivity value for the water column be supplied in the DEP file. If one is not supplied, then it calculates a value based on the first electrode pair. For this cruise, another system was acquiring data at the same time as the resistivity system. I took the data from that system which included conductivity and temperature measured values of the near surface water and reformatted these data text files that could be loaded into ArcMap as XY Event themes. The reformatting was accomplished with a locally written python script called r_nav.py.
Source_Used_Citation_Abbreviation: R720060908083041.RAW
Source_Used_Citation_Abbreviation: R720060908095700.RAW
Process_Date: 2006
Source_Produced_Citation_Abbreviation: R720060908083041.txt
Source_Produced_Citation_Abbreviation: R720060908095700.txt
Process_Step:
Process_Description:
These text files were then loaded into ArcMap 9.0 using Tools - Add XY data and setting the projection to Geographic, NAD83. Once the event layers were loaded into ArcMap they were converted to shapefiles using the Data Export option. The individual shapefiles were then merged into a single shapefile representing the Julian Day using ET GeoWizards version 9.
Source_Used_Citation_Abbreviation: R720060908083041.txt
Source_Used_Citation_Abbreviation: R720060908095700.txt
Process_Date: 2006
Source_Produced_Citation_Abbreviation: jd251_pnts.shp
Process_Step:
Process_Description:
I then used the resistivity calculator in VACExtras v. 1.95 to convert the temperature and salinity values to resistivity values with the units of ohm-m. The result of the calculation is to add an attribute to the shapefile called "resval". In the event that either the temperature or salinity value is not available, a resval of -9999 is used as the calculated value.
Source_Used_Citation_Abbreviation: jd251_pnts.shp
Process_Date: 2006
Source_Produced_Citation_Abbreviation: jd251_pnts.shp
Process_Step:
Process_Description:
I then used the ArcToolbox 9.0 Analysis tools - Proximity - Near tool with the following parameters: input feature - the points containing the calculated water resistivity values; near features - the resistivity tracklines from this particular Julian day; search radius - 40 meters. Running this tool added the fields NEAR_FID and NEAR_DIST to the input point shapefile containing the water resistivity values (jd251_pnts.shp). I chose a 40 meter radius because I wanted to exclude far away values so as not to skew results. The instrument collecting the water conductivity information does not track right on top of the CPR navigation, so comparing the two datasets indicated a 40 meter search radius was appropriate.
Source_Used_Citation_Abbreviation: jd251_pnts.shp
Source_Used_Citation_Abbreviation: resnavlns_jd251.shp
Process_Date: 2006
Source_Produced_Citation_Abbreviation: jd251_pnts.shp
Process_Step:
Process_Description:
I then created a text field called "resline" within the point shapefile using the attribute table option - Add field. I then joined the point shapefile to the polyline shapefile using the NEAR_FID attribute in the point shapefile and the FID attribute from the polyline shapefile. I selected all records within the joined table where NEAR_FID <> -1. the -1 is what is put for a point that doesn't fall near a line within the search radius (in the Near tool). I then copied over the line name attribute value from the polyline shapefile to the resline attribute within the point shapefile.
Source_Used_Citation_Abbreviation: jd251_pnts.shp
Source_Used_Citation_Abbreviation: resnavlns_jd251.shp
Process_Date: 2006
Process_Step:
Process_Description:
By selecting all the records for a given CRP line I can do the statistics to calculate the mean of the calculated water resistivity values. First I use the properties of the shapefile to define a definition query that will exclude all resistivity values that equal -9999 since this is essentially a NODATA value. Once this is done, the mean value is then used as the water resistivity value within the DEP file for that particular CRP line. This value is added to the appropriate location within the DEP file, and this file is then saved as *_lin_wres.dep where the * refers to the original line name. (* on this day refers to L20F1, L21f1, L22F1, L23F1, L24F1, L25F1, L25F2, L26F1).
Source_Used_Citation_Abbreviation: *_lin.dep
Process_Date: 2006
Source_Produced_Citation_Abbreviation: *_lin_wres.dep
Process_Step:
Process_Description:
EarthImager version 1.9.9 was used to process the data files. The *.ini file accompanying the results contains the parameters used during the processing. These parameters include: minimum voltage: 0.02; minimum abs(V/I): 2E-5; max repeat error: 3%; min apparent res: 0.03; max apparent res: 1000; max reciprocal error: 5%; remove spikes, smooth model inversion; finite element method; Cholesky decomposition; Dirichlet boundary condition; thickness incremental factor: 1.1; depth factor: 1.1; number of iterations: 8; stop criteria: max RMS 3%; error reduction 5%; L2Norm; CRP processing using a 65% overlap. These INI files can be loaded in EarthImager to help maintain consistent processing parameters for other datasets. When the files are processed, numerous files are generated. Because of the "roll-along" nature of the processing, each line takes several iterations of processing which are then combined into a single output. The output consists of numerous files including JPEG images and text files representing the XYZ position of each resistivity value. There are two JPEG image generated with each process - a long version and a short version. The JPEG files produced uses a color scale for the resistivity that is based on the data extent from that particular file. The JPEG images also include a plot of temperature along the line. In addition to the JPEG images, there are text files with the extensions of *.llt, and *.xyz. Each of these is a text file. The LLT file has four columns of information: longitude in decimal degrees, latitude in decimal degrees, depth in meters, and resistivity value in ohm-m. The XYZ file has three columns of information: distance along line in meters, depth in meters, and resistivity value in ohm-m. There was also a file created with a UTM extension, but the eastings and northing values were invalid so was omitted from this collection (software bug). An example of the file naming convention is as follows: For input files of L1F1_lin.stg and L1F1_lin_wres.dep the resulting series of output files are: L1F1_lin1_trial1.ini; L1F1_lin_AllInvRes.llt; L1F1_lin_AllInvRes.xyz; L1F1_lin_trial1_InvResLong.jpg; L1F1_lin_trial1_InvResShort.jpg. You can process an individual line as many times as you want and the software places the results in incrementing folder names starting with trial1. In addition, the STG and DEP used as input to the processing software are written to the results folder.
Source_Used_Citation_Abbreviation: *_lin.stg
Source_Used_Citation_Abbreviation: *_lin_wres.dep
Process_Date: 2006
Source_Produced_Citation_Abbreviation: *.ini
Source_Produced_Citation_Abbreviation: *.llt
Source_Produced_Citation_Abbreviation: *.xyz
Source_Produced_Citation_Abbreviation: *.jpg
Process_Step:
Process_Description:
The XYZ output file was then loaded into Matlab version 7.5.0.342 (R2007b), along with the depth information from the DEP file, to create a new JPEG image with the same color scale for all the data files. In this manner, the JPEG images can be compared directly. Care was taken to try to get the vertical and horizontal scales uniform as well, although this was not always possible due to Matlab limitations. These images reside in the "matlabimages" folder. These JPEG images include a black line within the resistivity profile which represents the sediment water interface based on the depth values from the DEP file. The local Matlab script used to load the data was cp_100m_potomac.m, while the local Matlab script used to export the JPEG image was exportfig.m.
Source_Used_Citation_Abbreviation: *.xyz
Source_Used_Citation_Abbreviation: *_lin_wres.dep
Process_Date: 2009
Source_Produced_Citation_Abbreviation: matlabimages/*.jpg
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: point
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.000001
Longitude_Resolution: 0.000001
Geographic_Coordinate_Units: Decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137.000000
Denominator_of_Flattening_Ratio: 298.257222
Vertical_Coordinate_System_Definition:
Depth_System_Definition:
Depth_Datum_Name: Local surface
Depth_Resolution: 0.1
Depth_Distance_Units: meters
Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: John F. Bratton
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2254
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: jbratton@usgs.gov
Resource_Description: Downloadable Data
Distribution_Liability:
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.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: WinZip
Format_Version_Number: 9.0
Format_Information_Content:
The WinZip file contains all the processed CRP data from Sept. 8, 2006 as well as the associated metadata files.
File_Decompression_Technique: WinZip
Transfer_Size: 21.4 MB
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
<https://pubs.usgs.gov/of/2009/1151/data/resistivity/proc_resis/sept8_proc.zip>
Network_Resource_Name: <https://pubs.usgs.gov/of/2009/1151/html/catalog.html>
Offline_Option:
Offline_Media: DVD-ROM
Recording_Capacity:
Recording_Density: 4.75
Recording_Density_Units: GBytes
Recording_Format: UDF
Fees: None.
Technical_Prerequisites:
The user must have software capable of uncompressing the WinZip file.
Metadata_Reference_Information:
Metadata_Date: 20090621
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
Metadata_Extensions:
Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>
Profile_Name: ESRI Metadata Profile
Metadata_Extensions:
Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>
Profile_Name: ESRI Metadata Profile
Generated by mp version 2.9.6 on Thu Mar 25 13:42:11 2010