Processed continuous resistivity profile data collected by the U.S. Geological Survey in Great South Bay on Long Island, New York, on Sept. 23, 2008

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Reference_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: John F. Bratton

Originator: VeeAnn A. Cross

Publication_Date: 2012

Title:

Processed continuous resistivity profile data collected by the U.S. Geological Survey in Great South Bay on Long Island, New York, on Sept. 23, 2008

Edition: 1

Series_Information:

Series_Name: Open-File Report

Issue_Identification: 2011-1040

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/2011/1040/data/resistivity/proc_resis/sept23_proc.zip>

Online_Linkage: <http://pubs.usgs.gov/of/2011/1040/html/catalog.html>

Larger_Work_Citation:

Citation_Information:

Originator: V.A. Cross

Originator: J.F. Bratton

Originator: K.D. Kroeger

Originator: J. Crusius

Originator: C.R. Worley

Publication_Date: 2012

Title:

Continuous Resistivity Profiling Data from Great South Bay, Long Island, New York

Edition: 1

Series_Information:

Series_Name: Open-File Report

Issue_Identification: 2011-1040

Publication_Information:

Publication_Place: Woods Hole Coastal and Marine Science Center, Woods Hole, MA

Publisher: U.S. Geological Survey, Coastal and Marine Geology Program

Other_Citation_Details: 1 DVD

Online_Linkage: <http://pubs.usgs.gov/of/2011/1040/>

Description:

Abstract:

An investigation of submarine aquifers adjacent to the Fire Island National Seashore and Long Island, New York, was conducted to assess the importance of submarine groundwater discharge (SGD) as a potential nonpoint source of nitrogen delivery to Great South Bay. More than 200 kilometers (km) of continuous resistivity profiling (CRP) data were collected to image the fresh-saline groundwater interface in sediments beneath the bay. In addition, groundwater sampling was performed at sites (1) along the northern shore of Great South Bay, particularly in Patchogue Bay, that were representative of the developed Long Island shoreline, and (2) at sites on and adjacent to Fire Island, a 50-km-long barrier island on the southern side of Great South Bay. Other field activities included sediment coring, stationary electrical resistivity profiling, and surveys of in-situ pore water conductivity. The onshore and offshore shallow hydrostratigraphy of the Great South Bay shorelines, particularly the presence and nature of submarine confining units, appears to exert primary control on the dimensions and chemistry of the submarine groundwater flow and discharge zones. Sediment coring has shown that the confining units commonly consist of drowned and buried peat layers likely deposited in salt marshes. Based on CRP data, low-salinity groundwater extends from 10 to 100 meters (m) offshore along much of the northern and southern shores of Great South Bay, especially off the mouths of tidal creeks, and beneath shallow flats to the north of Fire Island adjacent to modern salt marshes. Human modifications of much of the shoreline and nearshore areas along the northern shore of the bay, including filling of salt marshes, construction of bulkheads and piers, and dredging of navigation channels, has substantially altered the natural hydrogeology of the bay's shorelines by truncating confining units and increasing recharge near the shore in filled areas. Better understanding of the nature of SGD along developed and undeveloped shorelines of embayments such as this could lead to improved models and mitigation strategies for nutrient overenrichment of estuaries. For more information on the surveys involved in this project, see <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2008-007-FA> and <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2008-037-FA>.

Purpose:

This dataset provides the processed continuous resistivity profile (CRP) data collected on Sept. 23, 2008 in Great South Bay on Long Island, New York. The CRP system (AGI SuperSting) 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. This also acts as an archive of these data.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 20080923

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -73.033650

East_Bounding_Coordinate: -72.945867

North_Bounding_Coordinate: 40.750517

South_Bounding_Coordinate: 40.736617

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 Number 2008-037-FA

Theme_Keyword: Info Bank ID T-37-08-LI

Theme_Keyword: navigation

Theme_Keyword: bathymetry

Theme_Keyword: Continuous Resistivity Profiling

Theme_Keyword: CRP

Theme_Keyword: Lowrance GPS

Theme_Keyword: AGI SuperSting

Theme_Keyword: processed data

Theme_Keyword: groundwater

Theme_Keyword: submarine groundwater

Theme_Keyword: R/V Terrapin

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category

Theme_Keyword: elevation

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: New York

Place_Keyword: Long Island

Place_Keyword: Great South Bay

Place_Keyword: Fire Island

Place_Keyword: Suffolk County

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: 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

Native_Data_Set_Environment:

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.4000

Cross_Reference:

Citation_Information:

Originator: Advanced Geosciences, Inc.

Publication_Date: 2008

Title:

Instruction Manual for EarthImager 2D, version 2.2.8, Resistivity and IP inversion software

Publication_Information:

Publication_Place: Austin, Texas

Publisher: Advanced Geosciences, Inc.

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

Publication_Information:

Publication_Place: Austin, Texas

Publisher: Advanced Geosciences, Inc.

Online_Linkage: <http://www.agiusa.com>

Data_Quality_Information:

Logical_Consistency_Report:

All data collected on this day were collected with the 15-m streamer.

Completeness_Report:

All usable data collected on this day was processed. Files L17F1 and L33F1 did not have STG files, so could not be processed.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

The navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located at the anchor point for the resistivity streamer, which is also directly above the fathometer transducer mount point. The GPS system is published to be accurate to within 10 meters.

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

All collected bathymetry values were collected by the 200 kHz Lowrance fathometer. The fathometer was mounted starboard side aft, directly below the GPS antenna and the resistivity streamer tow point. The transducer was approximately 0.30 meters below the sea surface, and this draft was not corrected for. 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. Two different streamers were used for data collection - not simultaneously. One streamer was a 50-m streamer with an 11 electrode array with electrodes spaced 5 meters apart. The other streamer was a 15-m streamer with an 11 electrode array with electrodes spaced 1.5 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 ¼ the streamer length. So for the 50-m streamer, maximum depth is about 12.5 meters, while the 15 meter streamer can reach about 3.75 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 transducer also contains a temperature sensor. Lowrance indicates the speed of sound used by the system is 4800 feet/second. 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.

Process_Step:

Process_Description:

The resistivity data (*.stg) were merged with the navigation data (*.gps) 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 1.3.4.217. The GPS offset in MLM was set to +2 because an offset value of 0 was used during data acquisition, yet the offset from the GPS antenna to the first electrode was 2 meters. The output from this process is a linearized STG file and a DEP file which contains water depths at distances along line. 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: 200809

Source_Produced_Citation_Abbreviation: *lin.stg

Source_Produced_Citation_Abbreviation: *.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:

Initially attempting to run L17F2 through MLM indicated too many navigation errors. A 30 second gap in the navigation was causing the problem which was adjusted for in the software INI file allowing a gap that large. Initial processing indicated a spike in the water column in L19F1 so the original STG file (L19F1.stg) was copied to L19F1_mod.stg and the electrodes associated with the anomaly at time 164957 were deleted.

Source_Used_Citation_Abbreviation: *.stg

Process_Date: 200810

Source_Produced_Citation_Abbreviation: *mod.stg

Process_Step:

Process_Description:

Each DEP file was checked for anomalous bathymetry values, or duplicated distance along values, and those lines in the file were deleted.

Process_Date: 200810

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 salinity was measured on a water sample taken from the bay. The salinity was measured at 25 ppt. Using an average water temperature of 19.45 degrees Celsius, a resistivity value of 0.29 ohm-m was calculated to use for the data processing. This calculation was done using the website <http://www2.sese.uwa.edu.au/~hollings/pilot/denscalc.html> and using the 1/conductivity for the result. The water resistivity value was added to the appropriate place in the DEP files so that a known water resistivity value would be used in the calculations. As of 2012, the website for the density calculation has changed: <http://fermi.jhuapl.edu/denscalc.html>.

Source_Used_Citation_Abbreviation: *.dep

Process_Date: 200810

Source_Produced_Citation_Abbreviation: *wres.dep

Process_Step:

Process_Description:

EarthImager version 2.2.8 build 562 was then 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 negative resistivity, smooth model inversion; finite element method; Cholesky decomposition; Dirichlet boundary condition; thickness incremental factor: 1.1; depth factor: 1.1; max number of CG iterations: 100; stop criteria: number of iterations 8; 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. 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 when possible - a long version with the x-axis labeled with latitude and longitude values and a corresponding short version of the same information. The JPEG files produced use 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. 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. These data represent in most cases trial2, which is the processing with the water resistivity value. Because some of the files collected on this day are so short, the roll-along component of the processing was unnecessary. For this reason, the JPEG image and the XYZ data had to be saved manually. First, just the inverted resistivity line is displayed using View - Inverted Resistivity Section. Then the image can be saved using File - Save Image. And finally, the XYZ data had to be saved manually using File - Save Data in XYZ format. The XYZ output file extension is DAT instead of XYZ. This DAT file three columns of information: distance along line in meters, depth in meters, and resistivity value in ohm-m. Automatically generated is the file with the LLT extension. 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. These shorter data files also represent trial2 which is the processing with the water resistivity value. The white line appearing in most of the JPEG images is the seafloor position based on the bathymetry.

Source_Used_Citation_Abbreviation: *lin.stg

Source_Used_Citation_Abbreviation: *wres.dep

Process_Date: 200810

Source_Produced_Citation_Abbreviation: *.ini

Source_Produced_Citation_Abbreviation: *.llt

Source_Produced_Citation_Abbreviation: *.xyz or *.dat

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 15-m streamer data was cp_gsbay_15m.m. The local MATLAB script used to export the JPEG image was exportfig.m.

Source_Used_Citation_Abbreviation: *.xyz or *.dat

Source_Used_Citation_Abbreviation: *wres.dep

Process_Date: 201010

Source_Produced_Citation_Abbreviation: *.jpg

Process_Step:

Process_Description:

Corel PhotoPaint v. 11 was used to crop excess white space from around the MATLAB resistivity profile JPEG images, saving the JPEGs with the same filename.

Source_Used_Citation_Abbreviation: *.jpg

Process_Date: 201010

Source_Produced_Citation_Abbreviation: *.jpg

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: D_WGS_1984

Ellipsoid_Name: WGS_1984

Semi-major_Axis: 6378137.000000

Denominator_of_Flattening_Ratio: 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: Explicit depth coordinate included with horizontal coordinates

Distribution_Information:

Distributor:

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

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. 23, 2008 as well as the associated metadata files.

Transfer_Size: 19.2 MB

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

<http://pubs.usgs.gov/of/2011/1040/data/resistivity/proc_resis/sept23_proc.zip>

Network_Resource_Name: <http://pubs.usgs.gov/of/2011/1040/html/catalog.html>

Fees: None.

Technical_Prerequisites:

The data are provided in a WinZip compressed file. The user must have software capable of uncompressing the archive. In addition, portions of the processed data are available in a format compatible with AGI Geosciences EarthImager software. The user must have software capable of reading the AGI format in order to process these data. The data are also available in an XYZ ASCII format.

Metadata_Reference_Information:

Metadata_Date: 20121116

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