A GIS compilation of vector shorelines for the Virginia coastal region from the 1840s to 2010s

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Frequently anticipated questions:

What does this data set describe?

Title:
A GIS compilation of vector shorelines for the Virginia coastal region from the 1840s to 2010s
Abstract:
The U.S. Geological Survey (USGS) has compiled national shoreline data for more than 20 years to document coastal change and serve the needs of research, management, and the public. Maintaining a record of historical shoreline positions is an effective method to monitor national shoreline evolution over time, enabling scientists to identify areas most susceptible to erosion or accretion. These data can help coastal managers and planners understand which areas of the coast are vulnerable to change.
This data release includes a compilation of previously published historical shoreline positions for Virginia spanning 148 years (1849-1997), and two new mean high water (MHW) shorelines extracted from lidar data collected in 2010 and 2017. These data provide a standardized shoreline database for the state. This release includes both long-term (up to 168 years) and short term (~20 years) rates. Files associated with the long-term and short-term rates are appended with "LT" and "ST", respectively. A proxy-datum bias reference line that accounts for the positional difference in a proxy shoreline (e.g. High Water Line (HWL) shoreline) and a datum shoreline (e.g. MHW shoreline) is also included in this release.
Supplemental_Information:
This dataset uses two methods of shoreline extraction from lidar; the profile and the contour methods. Described in Farris and others (2018), the profile method extracts the MHW position from point cloud data using a Matlab based approach. The contour method extracts the elevation from a Digtal Elevation Model (DEM) using the ArcMap tool "Contour List" with the MHW value chosen for the contour. Cross-referenced citations are applicable to the dataset as a whole.
  1. How might this data set be cited?
    Bartlett, Marie K., and Farris, Amy S., 20230526, A GIS compilation of vector shorelines for the Virginia coastal region from the 1840s to 2010s: data release doi:10.5066/P9DHOFXU, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Bartlett, Marie K., Henderson, Rachel E., and Farris, Amy S., 2023, USGS National Shoreline Change — A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for Coastal Virginia from the 1840s to 2010s: data release doi:10.5066/P9DHOFXU, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Bartlett, M.K., Henderson R.E., and Farris, A.S., 2023, USGS National Shoreline Change — A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for Coastal Virginia from the 1840s to 2010s: U.S. Geological Survey data release, https://doi.org/10.5066/P9DHOFXU.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.0822
    East_Bounding_Coordinate: -75.2371
    North_Bounding_Coordinate: 38.0275
    South_Bounding_Coordinate: 36.5488
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/641c6304d34e807d39b63fc0?name=VA_shorelines_browse.JPG (JPEG)
    Map view of dataset.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date:
    Ending_Date: 2017
    Currentness_Reference:
    ground condition at the time of each survey
  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):
      • String (452)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in meters
      The horizontal datum used is WGS_1984.
      The ellipsoid used is WGS_84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    VA_shorelines.shp Attribute Table
    This dataset includes polyline shorelines spanning 168 years from 1849 to 2017 for the coastal region of Virginia. (Source: U.S. Geological Survey (USGS))
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Feature geometry. These shorelines are polyline shapefiles.
    Year_
    Four-digit year of shoreline. (Source: USGS)
    Range of values
    Minimum:1849
    Maximum:2017
    Date_
    Date of shoreline position; date of survey as indicated on source material. A default date of 07/01 was assigned to shorelines where only the year was known (month and day unknown). Using July, the mid-point month of the calendar year, minimizes the potential offset to the actual shoreline date by a maximum of six months. (Source: USGS) Date is in mm/dd/yyyy format
    Uncy
    Estimate of shoreline position uncertainty in meters. Actual shoreline position is assumed to be within the range of this value (plus or minus, meters). Methods used to calculate the uncertainty are listed in the process steps. (Source: USGS)
    Range of values
    Minimum:1.301
    Maximum:16.327
    Source
    Agency that provided shoreline feature or the data source used (e.g. T-sheet) to digitize shoreline feature. (Source: USGS)
    ValueDefinition
    USGSUSGS provided the shoreline feature or the data source used to digitize shoreline feature.
    Source_b
    Method of deriving shoreline feature, if known. (Source: USGS)
    ValueDefinition
    LidarShoreline extraction from lidar
    CERC mapShoreline derived from Coastal Engineering Research Center (CERC map). See USGS data release doi:10.3133/ofr20101119
    T-6240bShoreline derived from NOAA T-sheet. See USGS data release doi:10.3133/ofr20101119
    VA LT Ecol PrjShoreline derived from Virginia Coast Reserve Long-Term Ecological Research Project (VA LT Ecol PRJ). See USGS data release doi:10.3133/ofr20101119
    Default_D
    Differentiates between shorelines that have known month and day attributes and those that use the default value of 07/01 when only the year is known. (Source: USGS)
    ValueDefinition
    1Shoreline month and day are unknown and default value of 07/01 was used.
    0Shoreline month and day are known.
    Type
    The vertical shoreline reference used for shoreline extraction (MHW or HWL). (Source: USGS)
    ValueDefinition
    MHWMean high water - a datum-based reference
    HWLHigh water line - a proxy-based historical shoreline
    Method
    Method of shoreline extraction from lidar - contour or profile. Does not apply to pre-1997 shorelines. See Farris and others (2018) for details. (Source: USGS)
    ValueDefinition
    blankNot a lidar based shoreline; method does not apply.
    contourMHW contour value of 0.26 m
    profileProfile method was used with a MHW elevation of 0.26 m.
    Shape_Leng
    Length of feature/transect in meter units (WGS 1984 UTM Zone 18N) (Source: USGS)
    Range of values
    Minimum:5.711
    Maximum:32354.292
    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with the dataset. Please review the individual attribute descriptions for detailed information.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Marie K. Bartlett
    • Amy S. Farris
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Marie K. Bartlett
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA

    508-457-8700 x2306 (voice)
    mbartlett@usgs.gov

Why was the data set created?

This compilation of historical shoreline positions is used to describe the movement of beaches through time. This dataset includes shorelines from 168 years ranging from 1844 to 2017 for the coastal region of Virginia. The purpose of these data are to calculate rates of shoreline change for the Virginia coastal region to maintain a national assessment of shoreline change.

How was the data set created?

  1. From what previous works were the data drawn?
    VA_historical (source 1 of 4)
    Himmelstoss, Emily, Kratzmann, Meredith, Hapke, Cheryl, Thieler, Robert, and List, Jeffrey, 20101119, The National Assessment of Shoreline Change: A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for the New England and Mid-Atlantic Coasts: Open-File Report 2010-1119.

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy
    Source_Contribution:
    Historical shorelines were imported to combine with lidar shorelines for the new VA shoreline database.
    2017 Lidar (source 2 of 4)
    NOAA Office for Coastal Management (NOAA/OCM), 20170913, 2017 USACE NCMP Topobathy Lidar: East Coast (NY, NJ, DE, MD, VA, NC, SC, GA): NOAA's Ocean Service, Coastal Services Center (CSC), Charleston, SC.

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to extract shorelines using methods described in the process steps. The data were downloaded using the cart feature in UTM Zone 18 projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2010 Lidar (source 3 of 4)
    NOAA Office for Coastal Management (NOAA/OCM), 20140522, 2010 US Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Technical Center of eXpertise (JALBTCX) Lidar: Virginia (Topo): NOAA's Ocean Service, Coastal Services Center (CSC), Charleston, SC.

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to extract shorelines using methods described in the process steps. The data were downloaded using the cart feature in UTM Zone 18 projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2017 DEM (source 4 of 4)
    NOAA Office for Coastal Management (NOAA/OCM), 20170913, 2017 USACE NCMP Topobathy Lidar DEM: East Coast (NY, NJ, DE, MD, VA, NC, SC, GA).

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy
    Source_Contribution:
    The raster digital elevation model (in GeoTIFF format) was used to extract a small portion of the 2017 polyline shoreline.
  2. How were the data generated, processed, and modified?
    Date: 2022 (process 1 of 5)
    Historical shoreline data covering the coast of Virginia from the previously published National Assessment of Shoreline Change: Historical Shoreline Change along the New England and Mid-Atlantic Coasts (USGS Open-File Report 2010-1119) were compiled and merged into a single feature class within a personal geodatabase in ArcMap v 10.7.1. The data were projected in ArcToolbox v10.7.1 > Data Management Tools > Projections and Transformations > Feature > Project. Parameters: input projection = geographic coordinates (WGS84); output projection = UTM zone 18N (WGS 84); transformation = none. Historical shoreline data covers date range 1849-1997 and includes one lidar-derived shoreline (1997). Some shoreline segments from 1962 were removed because they represented the wrong feature. See associated source metadata (https://pubs.usgs.gov/of/2010/1119/title_page.html) for complete process steps for historical shoreline delineation. Person who carried out this activity:
    Marie K. Bartlett
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x 2306 (voice)
    mbartlett@usgs.gov
    Data sources used in this process:
    • VA_historical
    Date: 2022 (process 2 of 5)
    MHW shorelines are datum-based and in the case of the shorelines used here, were extracted from lidar data using a profile method, whenever possible, or a contour method. For both methods, a MHW elevation of 0.26 m was obtained from Weber and others (2005).
    Date: 2022 (process 3 of 5)
    The profile method used to extract the operational MHW shoreline from the lidar point cloud data utilizing the Matlab-based approach (Matlab version 2019b) is described in Farris and others (2018). The profile method used a coast-following reference line with 20-meter spaced profiles. All lidar data points that were within 1 meter of each profile line were associated with that profile. All processing was done on the 2-meter-wide profiles, working on a single profile at a time. For each profile, a linear regression was fit through data points on the foreshore and the regression was evaluated at the MHW elevation to yield the cross-shore position of the MHW shoreline. If there was a data gap at MHW or if the MHW elevation was obscured by water points, the linear regression was simply extrapolated to the MHW elevation. For each profile, the foreshore beach slope was defined as the slope of the regression line. This slope is stored and later used for the calculation of the proxy-datum bias feature. Each MHW shoreline point that was extracted using this profile method has an uncertainty associated with it. For the new 2010 and 2017 lidar shoreline, this uncertainty includes four components: 1) the 95% confidence interval on the linear regression estimate of the shoreline position; 2) the vertical error of the raw lidar data as reported in the metadata; 3) a 15 cm vertical error in our chosen value of MHW, and; 4) the uncertainty due to extrapolation (if the shoreline was determined using extrapolation). These four components of uncertainty were added in quadrature to yield a total error for each shoreline point. The 2010 shoreline extraction was performed by Amy S. Farris The 2017 shoreline extraction was performed by Marie K. Bartlett Data sources used in this process:
    • 2017 Lidar
    • 2010 Lidar
    Date: 2023 (process 4 of 5)
    One small (~6k) section of the 2017 lidar shoreline was extracted using a contour method, with a MHW elevation of 0.26 m determined from Weber and others (2005). To extract the MHW shoreline from each DEM surface, the operational MHW elevation was entered into the ArcGIS tool Contour List as the contour value. This step was iterated for each individual DEM in the study area. As a result, individual shapefiles were created for each DEM. The shoreline was then manually edited with the lidar data displayed with categorized elevation values to highlight the MHW values. Segments of the contour that did not fall near MHW were removed. Sometimes the lidar data did not extend down to MHW, resulting in gaps in the contour. Each contour shoreline was generalized using the Smooth Line tool (ArcToolbox > Cartography > Generalization > Smooth Line), applying the PAEK algorithm with a 5 m tolerance. The shoreline features were then merged (ArcToolbox > Data Management > General > Merge) into one feature class. The contour shoreline segments were given the positional uncertainty of the adjacent profile shoreline segments, which was 2.15879. The resulting contour shoreline was merged with the profile method shoreline using the Merge tool in Esri’s ArcToolbox > Data management > General > Merge to generate one complete 2017 shoreline file for the state. Data sources used in this process:
    • VA_historical
    • 2017 Lidar
    • 2010 Lidar
    • 2017 DEM
    Date: 2022 (process 5 of 5)
    The profile method shorelines, contour shoreline segment, and historical shorelines were confirmed to have the same attribute fields required for use in DSAS before they were merged into a single feature class using Esri's ArcToolbox > Data Management > General > Merge. After rate calculations, the feature class was exported out of the geodatabase to shapefile format by right-clicking on the feature class name in the table of contents of the ArcMap project and choosing Export > Shapefile (single); Coordinate System: UTM Zone 18N (WGS84)
  3. What similar or related data should the user be aware of?
    Hapke, Cheryl J., Himmelstoss, Emily A., Kraztmann, Meredith G., List, Jeffrey H., and Thieler, E. Robert, 20120423, National Assessment of Shoreline Change: Historical Shoreline Change along the New England and Mid-Atlantic Coasts: Open-File Report 2010-1118, U.S. Geological Survey, Reston, VA.

    Online Links:

    Himmelstoss, Emily A., Farris, Amy S., Henderson, Rachel E., Kratzmann, Meredith G., Ergul, Ayhan, Zhang, Ouya, Zichichi, Jessica L., and Thieler, E. Robert, 2018, Digital Shoreline Analysis System (version 5.1): U.S. Geological Survey Software: software release version 5.1, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Use the first two links to access the software. The third link directs to the DSAS project page. Current software at time of use was 5.1.
    Himmelstoss, Emily A., Henderson, Rachel E., Kratzmann, Meredith G., and Farris, Amy S., 20211019, Digital Shoreline Analysis System (DSAS) version 5.1 User Guide: Open-File Report 2021-1091, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Use the first two access the user guide. The third link directs to the DSAS project page.
    Ruggiero, Peter, and List, Jeffrey H., 200909, Improving Accuracy and Statistical Reliability of Shoreline Position and Change Rate Estimates: Journal of Coastal Research vol. 255, Coastal Education and Research Foundation, West Palm Beach, Florida.

    Online Links:

    Other_Citation_Details: ppg. 1069-1081
    Weber, Kathryn M., List, Jeffrey H., and Morgan, Karen L.M., 2005, An operational mean high water datum for determination of shoreline position from topographic Lidar data: Open-File Report 2005-1027, U.S. Geological Survey, Reston, VA.

    Online Links:

    Farris, Amy S., Weber, Kathryn M., Doran, Kara S., and List, Jeffrey H., 2018, Comparing Methods Used by the U.S. Geological Survey Coastal and Marine Geology Program for Deriving Shoreline Position from Lidar Data: Open-File Report 2018-1121, U.S. Geological Survey, Reston, VA.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The data provided here are a compilation of shorelines from multiple sources, spanning 168 years. The attributes are based on the requirements of the Digital Shoreline Analysis System (DSAS) software and have gone through a series of quality assurance procedures.
  2. How accurate are the geographic locations?
    The horizontal accuracy of these shoreline data varies with respect to the data source from which the shorelines were derived. Shorelines prior to 1950 have an estimated positional uncertainty of plus or minus 10.8 meters. Shorelines from 1960-1980 have an estimated positional uncertainty of plus or minus 5.1 meters. Air photo-derived shorelines from 1990-2000s have an estimated positional uncertainty of plus or minus 3.2 meters. The lidar shoreline from 1997 has an estimated positional uncertainty of plus or minus 2.3 meters. All uncertainty values and extracted methods for shorelines prior to 2010 can be found in Himmelstoss and others (2010). Positional uncertainty associated with the new lidar shorelines (2010, 2017) was calculated at each transect and includes four components: 1) the 95% confidence interval on the linear regression estimate of the shoreline position; 2) the vertical error of the raw lidar data as reported in the metadata; 3) a 15 cm vertical error in our chosen value of MHW, and; 4) the uncertainty due to extrapolation (if the shoreline was determined using extrapolation). Along with the uncertainty associated with shorelines extracted using this method, there is also a horizontal offset between the datum-based lidar MHW shorelines and the proxy-based historical shorelines such as those derived from T-sheets and aerial photos. This offset nearly always acts in one direction and these uncertainties and offsets are accounted for in the associated shoreline changes rates and a proxy-datum bias feature.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This shoreline dataset is a mean high water (MHW) datum-based shoreline extracted using both the contour and the profile method (Farris and others 2018). See process steps for description of use. This shoreline file is complete and contains all historical shoreline segments used to calculate shoreline change rates along sections of the Virginia coastal region where shoreline position data were available. These data adequately represented the shoreline position at the time of the survey. Remaining gaps in these data, if applicable, are a consequence of non-existing data or existing data that did not meet quality assurance standards.
  5. How consistent are the relationships among the observations, including topology?
    Adjacent shoreline segments do not overlap and are not necessarily continuous. Shorelines were quality checked for accuracy. Any slight offsets between adjacent segments due to georeferencing and digitizing error are considered in the uncertainty calculations included in the attribute table. These data contain some short line segments (less than 30 meters) that were part of how the data were originally compiled and are in fact continuous with other segments of a given shoreline.

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 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. These data are not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: GS ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains the polyline shapefile of Virginia shoreline positions used to calculate long and short-term rates of change (VA_shorelines.shp and other shapefile components), browse graphic (VA_shorelines_browse.JPG), and the FGDC CSDGM metadata in XML format.
  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. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), and have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. 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?
    • Availability in digital form:
      Data format: These files (.cpg, .dbf, .prj, .sbn, .sbx, .shp, and .shx) are a collection of files with a common filename prefix and must be downloaded and stored in the same directory. Together they are the components of the shapefile. Additional files of the same name included are FGDC CSDGM-compliant metadata in XML format. in format Shapefile (version ArcGIS 10.7.1) Esri polyline shapefile Size: 0.82
      Network links: https://www.sciencebase.gov/catalog/item/641c6304d34e807d39b63fc0
    • Cost to order the data: none

Who wrote the metadata?

Dates:
Last modified: 26-May-2023
Metadata author:
Marie K. Bartlett
U.S. Geological Survey
384 Woods Hole Rd
Woods Hole, MA
USA

508-548-8700 x2306 (voice)
whsc_data_contact@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/SB_data_release/DR_P9DHOFXU/VA_shorelines.faq.html>
Generated by mp version 2.9.51 on Sun May 28 18:02:42 2023