Digital Shoreline Analysis System version 4.1 Transects with Long-Term Rate Calculations for the Delmarva South/Southern Virginia region from Wallops Island, Virginia to the Virginia/North Carolina border (DelmarvaS_SVA_LT.shp)

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Frequently anticipated questions:

What does this data set describe?

Title:
Digital Shoreline Analysis System version 4.1 Transects with Long-Term Rate Calculations for the Delmarva South/Southern Virginia region from Wallops Island, Virginia to the Virginia/North Carolina border (DelmarvaS_SVA_LT.shp)
Abstract:
Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the fact that coastal infrastructure is subjected to flooding and erosion. As a result, there is an increased demand for accurate information regarding past and present shoreline changes. To meet these national needs, the Coastal and Marine Geology Program of the U.S. Geological Survey (USGS) is compiling existing reliable historical shoreline data along open-ocean sandy shores of the conterminous United States and parts of Alaska and Hawaii under the National Assessment of Shoreline Change project. There is no widely accepted standard for analyzing shoreline change. Existing shoreline data measurements and rate calculation methods vary from study to study and prevent combining results into state-wide or regional assessments. The impetus behind the National Assessment project was to develop a standardized method of measuring changes in shoreline position that is consistent from coast to coast. The goal was to facilitate the process of periodically and systematically updating the results in an internally consistent manner.
  1. How might this data set be cited?
    U.S. Geological Survey, 2010, Digital Shoreline Analysis System version 4.1 Transects with Long-Term Rate Calculations for the Delmarva South/Southern Virginia region from Wallops Island, Virginia to the Virginia/North Carolina border (DelmarvaS_SVA_LT.shp): Open-File Report 2010-1119, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Himmelstoss, Emily A., Kratzmann, Meredith G., Hapke, Cheryl J., Thieler, E. Robert, and List, Jeffrey, 2010, 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, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.011356
    East_Bounding_Coordinate: -75.421271
    North_Bounding_Coordinate: 37.885359
    South_Bounding_Coordinate: 36.548610
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2010
    Currentness_Reference:
    publication date
  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 (2657)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    DelmarvaS_SVA_LT
    Transects are automatically generated by DSAS at a 90 degree angle to the user-specified baseline. (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    SHAPE
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    OBJECTID
    Internal feature number generated for each row of the transect attribute table when stored as a feature class in a geodatabase. This value is the common attribute field when joining to the TransectID value in long-term results output table calculated by DSAS. (Source: USGS) Sequential unique whole numbers that are automatically generated.
    BaselineID
    Unique identification number of the baseline segment. If BaselineID=0 no transects will be generated. Used by DSAS to determine transect ordering alongshore if multiple baseline segments exist. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:unlimited
    TransOrder
    Assigned by DSAS based on ordering of transects along the baseline. Used to allow user to sort transect data along the baseline from baseline start to baseline end. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:unlimited
    ProcTime
    Assigned by DSAS automatically to record the date and time a transect was processed. (Source: U.S. Geological Survey)
    Range of values
    Minimum:no value (when transect was manually created by user)
    Maximum:unlimited (values based on time and date of automatic generation)
    Autogen
    Assigned by DSAS to indicate whether or not a transect was automatically created by DSAS (1= transect was auto generated by DSAS; blank or 0=transect was not auto-generated). (Source: U.S. Geological Survey)
    Range of values
    Minimum:blank 0
    Maximum:1
    StartX
    Assigned by DSAS automatically to record the X coordinate of the beginning of the transect in meter units (UTM zone 18N, NAD 83). (Source: U.S. Geological Survey) Values based on data set extent. When blank, transect was manually created by user.
    StartY
    Assigned by DSAS automatically to record the Y coordinate of the beginning of the transect in meter units (UTM zone 18N, NAD 83). (Source: U.S. Geological Survey) Values based on data set extent. When blank, transect was manually created by user.
    EndX
    Assigned by DSAS automatically to record the X coordinate of the end of the transect in meter units (UTM zone 18N, NAD 83). (Source: U.S. Geological Survey) Values based on data set extent. When blank, transect was manually created by user.
    EndY
    Assigned by DSAS automatically to record the Y coordinate of the end of the transect in meter units (UTM zone 18N, NAD 83). (Source: U.S. Geological Survey) Values based on data set extent. When blank, transect was manually created by user.
    Azimuth
    Assigned by DSAS to record the azimuth of the transect measure in degrees clockwise from North. When zero, transect was manually created by user. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:360
    SHAPE_Leng
    Length of feature in meter units (UTM zone 18N, NAD 83). (Source: ESRI)
    Range of values
    Minimum:1508.509818
    Maximum:3344.23695
    TransectID
    Same value as ObjectID. Used as a permanent and unique identification number for each transect in the output rates table calculated by DSAS. This attribute was used as the common field when joining the rates table (.dbf) to the transect feature class in a geodatabase. (Source: U.S. Geological Survey) Positive real numbers that are automatically generated.
    LRR
    A linear regression rate-of-change statistic was calculated by fitting a least-squares regression line to all shoreline points for a particular transect. The best-fit regression line is placed so that the sum of the squared residuals (determined by squaring the offset distance of each data point from the regression line and adding the squared residuals together) is minimized. The linear regression rate is the slope of the line. The rate is reported in meters per year with positive values indicating accretion and negative values indicating erosion. (Source: U.S. Geological Survey)
    Range of values
    Minimum:-18.53
    Maximum:10.03
    LR2
    The R-squared statistic, or coefficient of determination, is the percentage of variance in the data that is explained by a regression. It is a dimensionless index that ranges from 1.0 to 0.0 and measures how successfully the best-fit line accounts for variation in the data. The smaller the variability of the residual values around the regression line relative to the overall variability, the better the prediction (and closer the R-squared value is to 1.0). (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:1
    LSE
    The predicted (or estimated) values of y (the distance from baseline in meters) are computed for each shoreline point by using the values of x (the shoreline date) and solving the equation for the best-fit regression line (y=mx+b). The standard error is also called the standard deviation. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.86
    Maximum:592.28
    LCI90
    The standard error of the slope with confidence interval describes the uncertainty of the reported rate. The LRR rates are determined by a best-fit regression line for the shoreline data at each transect. The slope of this line is the reported rate of change (in meters/year). The confidence interval (LCI) is calculated by multiplying the standard error (also called the standard deviation) of the slope by the two-tailed test statistic at the user-specified 90 percent confidence. This value is often reported in conjunction with the slope to describe the confidence of the reported rate. For example: LRR = 1.2 LCI90 = 0.7 could be reported as a rate of 1.2 (+/-) 0.7 meters/year. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.02
    Maximum:18.24
    Entity_and_Attribute_Overview:
    All calculations for length are in meter units and were based on the UTM zone 18N NAD83 projection.
    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)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)

Why was the data set created?

This dataset consists of long-term (100+ years) shoreline change rates for the Delmarva South/Southern Virginia region from Wallops Island, Virginia to the Virginia/North Carolina border. Rate calculations were computed within a GIS using the Digital Shoreline Analysis System (DSAS) version 4.1, an ArcGIS extension developed by the U.S. Geological Survey. Long-term rates of shoreline change were calculated using a linear regression rate based on all available shoreline data. A reference baseline was used as the originating point for the orthogonal transects cast by the DSAS software. The transects intersect each shoreline establishing measurement points, which are then used to calculate long-term rates.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 20-Mar-2009 (process 1 of 11)
    Transect Features Generated using DSAS v4.1 in ArcMap v9.3. Parameters Used: baseline layer=DelmarvaS_SVA_baseline, baseline group field=NULL, transect spacing=50 meters, transect length=2500 meters, cast direction=AUTO-DETECT, baseline location=offshore, cast method=two leg, smoothing distance=50 meters, flip baselines=not selected. For additional details on these parameters, please see the DSAS help file distributed with the DSAS software, or visit the USGS website at: https://pubs.er.usgs.gov/publication/ofr20081278. This process step and all subsequent process steps were performed by the same person: Emily Himmelstoss. Person who carried out this activity:
    Emily Himmelstoss
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2262 (voice)
    508-457-2310 (FAX)
    ehimmelstoss@usgs.gov
    Date: 20-Mar-2009 (process 2 of 11)
    Some transects did not intersect all shorelines at the default transect length. These transects were manually lengthened in an edit session using standard editing tools in ArcMap v9.3.
    Date: 14-Jan-2010 (process 3 of 11)
    Rate Calculations Performed in DSAS v4.1 using ArcMap 9.3. Parameters Used: shoreline layer=DelmarvaS_SVA_shorelines, shoreline date field=Date_, shoreline uncertainty field name=Uncy, the default accuracy=10.8 meters, shoreline intersection parameters=nearest, stats calculations=[Linear Regression Rate (LRR)], shoreline threshold=4, confidence interval=90%, Output rate table name=DelmarvaS_SVA_transects_rates_20100114_144944.
    Date: 14-Jan-2010 (process 4 of 11)
    Shoreline rates table (DelmarvaS_SVA_transects_rates_20100114_144944.dbf) was joined to the transect feature class in ArcMap v9.3 by right-clicking on the transect layer > joins and relates > join > join attributes from a table. Parameters: join field - ObjectID; table to join - DelmarvaS_SVA_transects_rates_20100114_144944; field in table: TransectID; join options - keep only matching records.
    Date: 14-Jan-2010 (process 5 of 11)
    The joined transect feature class was exported to a shapefile in ArcMap v9.3 by right-clicking the transect layer > data > export data, permanently linking the joined rate fields to the transect attribute table.
    Date: 27-Apr-2010 (process 6 of 11)
    The exported transect shapefile was projected in ESRI's ArcToolbox (v.9.3) > Data Management Tools > Projections and Transformations > Feature > Project. Parameters: input projection - UTM zone 18N (NAD 83); output projection - geographic coordinates (WGS84); transformation - NAD_1983_To_WGS_1984_1
    Date: 17-Nov-2016 (process 7 of 11)
    Edits to the metadata were made to fix any errors that MP v 2.9.34 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Added an online link to the data in the identification section. Fixed cross-reference online links. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 07-Feb-2017 (process 8 of 11)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 26-Apr-2018 (process 9 of 11)
    Added keywords from Coastal and Marine Ecological Classification Standard (CMECS) to metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 18-Nov-2019 (process 10 of 11)
    Crossref DOI link was added as the first link in the metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 08-Sep-2020 (process 11 of 11)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Thieler, E.R., Himmelstoss, E.A., Zichichi, J.L., and Ergul, A., 2009, Digital Shoreline Analysis System (DSAS) version 4.0: an ArcGIS extension for calculating shoreline change: Open-File Report 2008-1278, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details: Current version is 4.1.
    Hapke, Cheryl J., Himmelstoss, Emily A., Kratzmann, Meredith G., List, Jeffrey, and Thieler, E. Robert, 2010, 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:

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

  1. How well have the observations been checked?
    The attributes of this dataset are based on the field requirements of the Digital Shoreline Analysis System and were automatically generated by the software during the generation of the transect layer or during the calculation of shoreline change rates performed by the software.
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This dataset contains the transects automatically generated by the DSAS software application that were used to calculate long-term shoreline change rates for the region. Additional transects may have been generated but did not intersect the minimum requirement of four shorelines, one of which must be the lidar-derived shoreline, to calculate long-term rates.
  5. How consistent are the relationships among the observations, including topology?
    These data were generated using DSAS v4.1, an automated software program which does not perform checks for fidelity of the input features. The transects were visually inspected and sometimes manually adjusted within a standard ArcMap edit session to adjust the position at which an individual transect intersected the shorelines.

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.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
  2. What's the catalog number I need to order this data set? Downloadable Data
  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. 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: This WinZip (version 9.0) file contains a shapefile of transects generated by the Digital Shoreline Analysis System including long-term rate calculations for the Delmarva South/Southern Virginia region from Wallops Island, Virginia to the Virginia/North Carolina border. in format Shapefile (version ArcGIS 9.3) ESRI polyline shapefile
      Network links: http://pubs.usgs.gov/of/2010/1119/data/DelmarvaS_SVA_LT.zip
    • Cost to order the data: None

  5. What hardware or software do I need in order to use the data set?
    This zip file contains data available in Environmental Systems Research Institute (ESRI) polyline shapefile format. The user must have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 18-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: Emily Himmelstoss
Geologist
384 Woods Hole Road
Woods Hole, MA
USA

508-548-8700 x2262 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240318)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2010-1119/DelmarvaS_SVA_LT.shp.faq.html>
Generated by mp version 2.9.51 on Mon Mar 25 16:05:31 2024