Maryland Coastal Bays Bathymetry Survey, Collected in 2000 and 2003

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Maryland Geological Survey, Maryland Department of Natural Resources
Publication_Date: Unpublished Material
Title:
Maryland Coastal Bays Bathymetry Survey, Collected in 2000 and 2003
Geospatial_Data_Presentation_Form: vector digital data
Other_Citation_Details:
Description of methods for collecting the hydrographic surveys and data reduction are included in final reports submitted to the Fisheries Service, Md. Dept. of Natural Resources and to CZM, DNR, respectively: Wells, D.V., and Ortt, R., Jr., 2001, Bathymetric Survey of Assawoman Bay, St. Martin River, Sinepuxent Bay and Newport Bay; Coastal and Estuarine Geology File Report No. 01-2, Maryland Geological Survey, 24, with Appendices. Wells, D.V., Ortt, R.A., VanRyswick, S., Conkwright, R.D., and Offerman, K.A., 2004, Bathymetric Survey of the Maryland portion of Chincoteague Bay, Maryland Geological Survey, Coastal and Estuarine Geology Program, File Report 04-04, 17 pp, with Appendices. Isle of Wight data was not included in above citations, but were collected in 2003.
Online_Linkage: http://science.nature.nps.gov/nrdata
Description:
Abstract:
This data set contains point data that represents individual soundings from hydrographic surveys collected in Coastal bays in 2000 and 2003. Depths are adjusted for tidal stage and referenced to NAVD88 datum
Purpose:
The purpose of this data set is to provide up-to-date bathymetric data in the coastal bays, the Resources Assessment Services, Maryland Geological Survey conducted hydrographic surveys in the Maryland's coastal bays using standard digital bathymetric methods. The objectives for this survey were to: 1) provide consistent, systematic bathymetric coverage of the study areas; and 2) develop a baseline bathymetric data set that may be expanded and/or used for comparison with surveys conducted in the future.
Supplemental_Information:
This data set contains the final adjusted soundings from hydrographic surveys collected within the Maryland coastal bays. The surveys were conducted in Assawoman Bay and St. Martin River between May 1and June 28, 2000, in Chincoteague Bay between May 31 and October 1, 2003, and in Isle of Wight Bay between October 2 and October 8, 2003.
Time_Period_of_Content:
Time_Period_Information:
Multiple_Dates/Times:
Single_Date/Time:
Calendar_Date: 2000
Single_Date/Time:
Calendar_Date: 2003
Currentness_Reference:
ground condition
Status:
Progress: In work
Maintenance_and_Update_Frequency: Unknown
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -75.383325
East_Bounding_Coordinate: -75.064365
North_Bounding_Coordinate: 38.458754
South_Bounding_Coordinate: 38.008368
Keywords:
Theme:
Theme_Keyword_Thesaurus: Assateague Island National Seashore Keyword Thesaurus
Theme_Keyword: geomorphology
Theme_Keyword: coastal dynamics
Theme_Keyword: dredging
Theme_Keyword: elevation
Theme_Keyword: bathymetry
Theme:
Theme_Keyword_Thesaurus: National Park Service Theme Category Thesaurus
Theme_Keyword: Geodetic / Surveying
Theme_Keyword: Elevation / Bathymetry
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Place:
Place_Keyword_Thesaurus: National Park System Unit Name Thesaurus
Place_Keyword: Assateague Island National Seashore
Place:
Place_Keyword_Thesaurus: National Park System Unit Code Thesaurus
Place_Keyword: ASIS
Place:
Place_Keyword_Thesaurus: Geographic Names Information System
Place_Keyword: North America
Place_Keyword: Maryland
Place_Keyword: Worcester County
Place_Keyword: Assateague Island National Seashore
Place_Keyword: MD Coastal Bays
Access_Constraints: None
Use_Constraints:
These data are not for navigational purposes. The Maryland Department of Natural Resources assumes no liability for uses of these data. Acknowledgment of the Maryland Geological Survey, and the Fisheries Service, both part of the Maryland Department of Natural Resources, and NOAA shall be made in products derived from these data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Assateague Island National Seashore
Contact_Position: GIS Specialist
Contact_Address:
Address_Type: mailing and physical address
Address:
7206 National Seashore Lane
City: Berlin
State_or_Province: Maryland
Postal_Code: 21811
Country: United States
Contact_Voice_Telephone: 410-641-1443
Contact_Facsimile_Telephone: 410-641-1099
Contact_Electronic_Mail_Address: asis_gis@nps.gov
Hours_of_Service: 8:00am-4:30pm
Data_Set_Credit:
Funding for bathymetric data collected in the Northern Coastal Bays of Maryland was provided by the Fisheries Service, Maryland Department of Natural Resources.  Financial assistance for the bathymetric survey of Chincoteague Bay was provide by the NOAA Coastal Services Center, NOAA Award No. NA17OC2689.
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.0.1324
Cross_Reference:
Citation_Information:
Originator: Maryland Geological Survey, Maryland Department of Natural Resources
Publication_Date: Unknown
Title:
Metadata for individual soundings from hydrographic surveys collected in Assateague and Chincoteague Bays in 2000 and 2003.
Geospatial_Data_Presentation_Form: vector digital data
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
unknown
Logical_Consistency_Report:
Position (Horizontal) Data: The Ashtech GPS unit was programmed to output location coordinates only if the following criteria were met: 1) position derived from at least six satellites with positions of 15 ° or greater above the horizon; 2) Position dilution of precision (PDOP) less than 5; and 3) DGPS signal less than 30 seconds old.  The Starlink DGPS tracked the signals from Cape Henry, Virginia, and Cape Henlopen, Delaware.  The receiver sent updates to the Ashtech based upon the station with the strongest signal.  The position latency, or time lag between the position update and the posted time of day (time of depth sounding), also was recorded and later used to filter out less accurate location data.  The Ashtech GPS-Starlink DGPS system provided for ± 1.5-meter accuracy.

Water Depths (Soundings): The Knudsen echo sounder was checked against known depths to reduce errors.  The echo sounder was calibrated throughout the entire range of water depths measured.  The recorded depths were adjusted after collection using a calibration equation derived from the calibrations conducted in the field.  The accuracy of the Kundsen echo sounder is +/- 0.01 meters.

To determine the actual water level during the time the hydrographic surveys were conducted, water level recorders were installed and operated at several locations within the areas being surveying.  Water level recorder systems manufactured by Global Water Instrumentation, Inc. were used for this study. The manufacturer calibrated the water level recorders prior to shipping.  Calibrations were confirmed in the field prior to deployment and again at the end of the study.  Each recorder, once installed, was surveyed using either traditional differential leveling techniques and/or GPS techniques to determine elevation of water level sensor, referenced to North America Vertical Datum of 1988 (NAVD88).
Completeness_Report:
The area covered by the data set includes navigable portions of Assawoman Bay, including Delaware, St. Martin River, Isle of Wight Bay, Sinepuxent Bay, Newport Bay, and the Maryland portion of Chincoteague Bay.  In the northern half of the study area (north of South Point in Sinepuxent Bay), soundings were collected on a grid spacing of 200 meters (east-west) by 1000 meters (north-south).  In Chincoteague Bay, soundings were collected on a grid spacing of 400 meters (east-west) by 1000 meters (north-south).  Bay bottom features missed by the hydrographic surveys (i.e., features lying between hydrographic survey lines, or features outside of surveyed areas) would not be represented in this data.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
The Ashtech GPS-Starlink DGPS system provides for ± 1.5-meter accuracy.   The accuracy of the post-processed horizontal GPS data is within 3.5 meters.  The figure takes in account of the average boat speed (4 knots or 2 m/sec) and GPS coordinate update latency (1000 msec).
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
The accuracy of the post-processed bathymetry data is estimated to be ± 0.2 meters (0.7 ft).  This estimate takes in account of the error introduced with the water level adjustments and elevation accuracy of the water level recorders.
Lineage:
Process_Step:
Process_Description:
Hydrographic surveys were conducted using a 17 ft Boston Whaler equipped with a 70 horsepower outboard engine.  Track lines followed predetermined NAD83 UTM northing gridlines or easting gridlines, which facilitated navigation of the whaler and allowed survey lines to be easily retraced for quality control and quality assurance (QA/QC) purposes and during future surveys.  Track lines were spaced 400 meters apart and extended from shore to shore (generally east-west).  Tie-in track lines were run every 1000 meters perpendicular to the shore-to-shore tracks lines.  Boundary surveys, following the shoreline, were also conducted to establish boundary (near-shore) conditions. 

Bathymetric data were collected using an Ashtech Reliance Precision GPS (model SCA-12S; L1 code and carrier) and a Knudsen 320B/P dual frequency echo sounder with sounding frequencies of 200 KHz and 28 KHz.  The echo sounder transducer is a KEL771 dual frequency transducer with a 200 KHz beam angle of 4 degrees and a 28 KHz beam angle of 29 degrees.  The echo sounder generated acoustic pulses for bottom recognition at a rate of 2 Hz.  The pulse width was set to automatically change between 0.2 mS and 0.8 mS depending on the depth of the water.  The transmitted acoustic wave reflected off the density gradient separating the water column from the bottom sediment.  The returned acoustic wave is received by the transducer, and the time separation between the sent and the returned wave is recorded.  This time separation is directly proportional to distance.  The recordings were then filtered for points that were outside of the gate window (2 meters) and integrated within the echo sounder to produce an accurate measurement from the transducer to the water/sediment interface.  At an average vessel speed of 4 knots, a depth sounding was collected approximately every 1.0 m (3.3 ft) along the survey track-lines.  To minimize pitch and roll, the transducer, used for both transmitting the pulse and receiving the echo signal, was mounted off the port side of the whaler, slightly aft of the vessel's center.  Because of the size of the boat and safety considerations, surveys were collected during "calm" conditions (waves = 1 ft).

The sounding data was stored along with the GPS location and positional latency in a laptop computer.  Navigation was provided through a Lowrance GlobalNav 212 GPS interfaced to a Lowrance DGPS beacon receiver.  A Starlink MRB-2 DGPS receiver provided DGPS signals to the Ashtech Reliance GPS system.  The Ashtech unit was programmed to output location coordinates only if the following criteria were met: 1) position derived from at least six satellites with positions of 15 ° or greater above the horizon; 2) Position dilution of precision (PDOP) less than 5; and 3) DGPS signal less than 30 seconds old.  DGPS differential corrections broadcast by the United States Coast Guard provided a real-time horizontal accuracy of 1 to 2 m [3 to 6 feet] using the Cape Henry, Virginia, and Cape Henlopen, Delaware, DGPS sites.  The Ashtech GPS, the Lowrance GPS, and the echo sounder were checked against known horizontal and vertical measurements during the survey.  The echo sounder was calibrated to obtain speed of sound correction and transducer offset.

The HF sounding data from the hydrographic surveys were processed to remove invalid depth data (invalid HF flag), depths less than 0.35 meters, "out of sequence" depths (e.g., fish, water column noise, multiples, etc.), and invalid location coordinates (GPS latency values > 1000 msec).  For soundings having the same geographic coordinates, the sounding with the higher latency was removed.

Sounding depth values were adjusted to account for the offset of the transducer below the water surface.  The offset value was derived from the calibration of the echo sounder.

The adjusted sounding depth values were then corrected to account for tide stage and/or wind effects.  To determine the actual water level during the time the hydrographic surveys were conducted, water level recorders were installed and operated at several locations within the areas being surveying.  Water levels from the water level recorder were interpolated to the exact times depth soundings were taken, and the interpolated water level were subtracted from the adjusted depth soundings, obtaining depths corrected to NAVD88, meters.
Process_Date: Unknown
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Assateague Island National Seashore
Contact_Position: GIS Specialist
Contact_Address:
Address_Type: mailing and physical address
Address:
7206 National Seashore Lane
City: Berlin
State_or_Province: Maryland
Postal_Code: 21811
Country: United States
Contact_Voice_Telephone: 410-641-1443
Contact_Facsimile_Telephone: 410-641-1099
Contact_Electronic_Mail_Address: asis_gis@nps.gov
Hours_of_Service: 8:00am-4:30pm
Process_Step:
Process_Description:
Dataset copied.
Source_Used_Citation_Abbreviation:
C:\Documents and Settings\nick villa\Desktop\Assateague Metadata\coastbay_water_jetty\CB_BathyPts2000
Process_Step:
Process_Description:
Metadata imported.
Source_Used_Citation_Abbreviation:
S:\Scratch\nick_temp\Metadata_Edits\Final_bay_water_jetty\CB_BathyPts2000.shp.xml
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Entity point
Point_and_Vector_Object_Count: 548593
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: Universal Transverse Mercator
Universal_Transverse_Mercator:
UTM_Zone_Number: 18
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.999600
Longitude_of_Central_Meridian: -75.000000
Latitude_of_Projection_Origin: 0.000000
False_Easting: 500000.000000
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 0.000000
Ordinate_Resolution: 0.000000
Planar_Distance_Units: meters
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:
Altitude_System_Definition:
Altitude_Datum_Name: North American Vertical Datum of 1988
Altitude_Resolution: 0.000000
Altitude_Distance_Units: meters
Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
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Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: MDCB_BathyPoints
Entity_Type_Definition:
Point marks location of a sounding, a measured depth of water. On hydrographic charts the soundings are adjusted to a specific plane of reference (sounding datum).
Entity_Type_Definition_Source:
ASIS
Attribute:
Attribute_Label: FID
Attribute_Definition:
Internal feature number.
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label: Shape
Attribute_Definition:
Unique number assigned during merging data in MSAccess
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Coordinates defining the features.
Attribute:
Attribute_Label: OBJECTID
Attribute_Definition:
Identification field
Attribute_Definition_Source:
ASIS
Attribute_Domain_Values:
Unrepresentable_Domain:
field used for point identification
Attribute:
Attribute_Label: Num
Attribute_Definition:
unknown
Attribute_Definition_Source:
ASIS
Attribute_Domain_Values:
Unrepresentable_Domain:
unknown
Attribute:
Attribute_Label: Project
Attribute_Definition:
Name of Project
Attribute_Definition_Source:
ASIS
Attribute_Domain_Values:
Unrepresentable_Domain:
Name of Project
Attribute:
Attribute_Label: Easting
Attribute_Definition:
Coordinate system used to identify exact feature location
Attribute_Definition_Source:
ASIS
Attribute_Domain_Values:
Unrepresentable_Domain:
UTM coordinates
Attribute:
Attribute_Label: Northing
Attribute_Definition:
Coordinate system used to identify exact feature location
Attribute_Definition_Source:
ASIS
Attribute_Domain_Values:
Unrepresentable_Domain:
UTM coordinates
Attribute:
Attribute_Label: Depth
Attribute_Definition:
Depth, in meters, of bay bottom (sediment surface) referenced to North America Vertical Datum of 1988 plane (NAVD88).  Depths are given as negative values, i.e. distance below reference plane.  In Maryland's coastal bays, the average bay water levels were within ±0.02 meters of NAVD88.
Attribute_Definition_Source:
Maryland Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
Depth of point
Attribute:
Attribute_Label: Time_
Attribute_Definition:
Time that sounding was recorded, given in hours since Jan. 1, 2000, 00 hour. Time is reference in UTC
Attribute_Definition_Source:
Maryland Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
Time of data collection
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Assateague Island National Seashore
Contact_Position: GIS Specialist
Contact_Address:
Address_Type: mailing and physical address
Address:
7206 National Seashore Lane
City: Berlin
State_or_Province: Maryland
Postal_Code: 21811
Country: United States
Contact_Voice_Telephone: 410-641-1443
Contact_Facsimile_Telephone: 410-641-1099
Contact_Electronic_Mail_Address: asis_gis@nps.gov
Hours_of_Service: 8:00am-4:30pm
Resource_Description: Downloadable Data
Distribution_Liability:
The National Park Service shall not be held liable for improper or incorrect use of the data described and/or contained herein. These data and related graphics (i.e. GIF or JPG format files) are not legal documents and are not intended to be used as such. The information contained in these data is dynamic and may change over time. The data are not better than the original sources from which they were derived. It is the responsibility of the data user to use the data appropriately and consistent within the limitations of geospatial data in general and these data in particular. The related graphics are intended to aid the data user in acquiring relevant data; it is not appropriate to use the related graphics as data. The National Park Service gives no warranty, expressed or implied, as to the accuracy, reliability, or completeness of these data. It is strongly recommended that these data are directly acquired from an NPS server and not indirectly through other sources which may have changed the data in some way. Although these data have been processed successfully on computer systems at the National Park Service, no warranty expressed or implied is made regarding the utility of the data on other systems for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Transfer_Size: 14.649
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: :http://nrdata.nps.gov/asis/asisdata/MDCB_BathyPoints.zip
Fees: None
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Metadata_Reference_Information:
Metadata_Date: 20070718
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Assateague Island National Seashore
Contact_Position: GIS Specialist
Contact_Address:
Address_Type: mailing and physical address
Address:
7206 National Seashore Lane
City: Berlin
State_or_Province: Maryland
Postal_Code: 21811
Country: United States
Contact_Voice_Telephone: 410-641-1443
Contact_Facsimile_Telephone: 410-641-1099
Contact_Electronic_Mail_Address: asis_gis@nps.gov
Hours_of_Service: 8:00am-4:30pm
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://nrdata.nps.gov/profiles/nps_profile.xml
Profile_Name: NPS Metadata Profile
Metadata_Extensions:
Online_Linkage: http://www.esri.com/metadata/esriprof80.html
Profile_Name: ESRI Metadata Profile
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