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. 6, 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: http://pubs.usgs.gov/of/2009/1151/data/resistivity/proc_resis/sept6_proc.zip Online_Linkage: http://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: http://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: 20060906 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -76.454833 East_Bounding_Coordinate: -76.310367 North_Bounding_Coordinate: 38.295767 South_Bounding_Coordinate: 37.946450 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 9.2.6.1500 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: All the bathymetric values from this day were collected by the ship's fathometer. This fathometer was hull mounted approximately mid-ship, relatively close to the navigation antenna. The 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 L1F1, L2F1, L3F1, L4F1, L5F1, and L6F1. 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: R720060906081737.RAW Source_Used_Citation_Abbreviation: R720060906085622.RAW Source_Used_Citation_Abbreviation: R720060906114709.RAW Source_Used_Citation_Abbreviation: R720060906150117.RAW Source_Used_Citation_Abbreviation: R720060906175949.RAW Process_Date: 2006 Source_Produced_Citation_Abbreviation: R720060906081737.txt Source_Produced_Citation_Abbreviation: R720060906085622.txt Source_Produced_Citation_Abbreviation: R720060906114709.txt Source_Produced_Citation_Abbreviation: R720060906150117.txt Source_Produced_Citation_Abbreviation: R720060906175949.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: R720060906081737.txt Source_Used_Citation_Abbreviation: R720060906085622.txt Source_Used_Citation_Abbreviation: R720060906114709.txt Source_Used_Citation_Abbreviation: R720060906150117.txt Source_Used_Citation_Abbreviation: R720060906175949.txt Process_Date: 2006 Source_Produced_Citation_Abbreviation: jd249_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: jd249_pnts.shp Process_Date: 2006 Source_Produced_Citation_Abbreviation: jd249_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 (jd249_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: jd249_pnts.shp Source_Used_Citation_Abbreviation: resnavlns_jd249.shp Process_Date: 2006 Source_Produced_Citation_Abbreviation: jd249_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: jd249_pnts.shp Source_Used_Citation_Abbreviation: resnavlns_jd249.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 L1F1, L2F1, L3F1, L4F1, L5F1 and L6F1). 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. 6, 2006 as well as the associated metadata files. File_Decompression_Technique: WinZip Transfer_Size: 14.7 MB Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://pubs.usgs.gov/of/2009/1151/data/resistivity/proc_resis/sept6_proc.zip Network_Resource_Name: http://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: 20100325 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