Baseline for the Long Island Sound coastal region generated to calculate shoreline change rates using the Digital Shoreline Analysis System version 5.1

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Frequently anticipated questions:

What does this data set describe?

Title:
Baseline for the Long Island Sound coastal region generated to calculate shoreline change rates using the Digital Shoreline Analysis System version 5.1
Abstract:
The U.S. Geological Survey (USGS) maintains shoreline positions for the United States coasts from various historical sources, such as aerial photographs or topographic surveys, and contemporary sources, such as lidar-point clouds and digital elevation models. Shorelines are compiled in a GIS and analyzed in the USGS Digital Shoreline Analysis System (DSAS) software to calculate rates of change. Keeping a record of historical shoreline positions is an effective method to monitor change over time, enabling scientists to identify areas most susceptible to erosion or accretion. These data can help coastal managers understand which areas of the coast are vulnerable to change. This data release, and other associated products, represents an expansion of the USGS national-scale shoreline database to include Long Island Sound (LIS) covering coastal areas in New York and Connecticut. The shoreline positions and shoreline change rates provide actionable information to homeowners, coastal communities, and managers of public and private properties to improve resiliency for coastal hazards in Long Island Sound.
  1. How might this data set be cited?
    Henderson, Rachel E., and Kratzmann, Meredith G., 20250922, Baseline for the Long Island Sound coastal region generated to calculate shoreline change rates using the Digital Shoreline Analysis System version 5.1: data release DOI:10.5066/P1TKEDFX, 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.

    Henderson, Rachel E., Kratzmann, Meredith G., Farris, Amy S., Lentz, Erika E., and Himmelstoss, Emily A., 2025, National Shoreline Change—A GIS compilation of vector shorelines and associated shoreline change data from the 1800s to the 2010s for the coast of Long Island Sound, New York and Connecticut: data release DOI:10.5066/P1TKEDFX, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    suggested citation: Henderson, R.E., Kratzmann, M.G., Farris, A.S., Lentz, E.E., and Himmelstoss, E.A., 2025, National Shoreline Change—A GIS compilation of vector shorelines and associated shoreline change data from the 1800s to the 2010s for the coast of Long Island Sound, New York and Connecticut: U.S. Geological Survey data release, https://doi.org/10.5066/P1TKEDFX
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.815765
    East_Bounding_Coordinate: -71.859252
    North_Bounding_Coordinate: 41.341911
    South_Bounding_Coordinate: 40.798104
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/67bfb09cd34e8876fcbfc9cc?name=LIS_baseline.jpg&allowOpen=true (JPEG)
    Map view of data, yellow line indicates linear extent of the baseline data.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2025
    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 (64)
    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 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is 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?
    LIS_baseline
    Table containing attribute information associated with the data set for Long Island Sound (LIS). (Source: U.S. Geological Survey)
    FID
    Internal feature number used as a unique identifier of an object within a table primarily used in shapefiles. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Feature type.
    Id
    Field required by the Digital Shoreline Analysis System (DSAS) software. DSAS uses this value to determine the ordering sequence of transects when the baseline feature contains multiple segments. Individual segments are numbered sequentially alongshore. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:64
    Location
    Geographic area (Source: U.S. Geological Survey)
    ValueDefinition
    Long Island Sound ConnecticutBaseline segments located in the state of Connecticut on the northern coast of Long Island Sound.
    Long Island Sound NY NBaseline segments located in the state of New York on the northern coast of Long Island Sound.
    Long Island Sound NY SBaseline segments located in the state of New York on the southern coast of Long Island Sound.
    Group_ID
    Group_ID is an optional field in DSAS that aggregates baseline segments on the basis of variations alongshore. Here, baseline segments are grouped by geographic location, south coast (1) or north coast (2) of Long Island Sound. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:2
    Shape_Leng
    Length of feature in meter units (UTM zone 18N, NAD 83) (Source: Esri)
    Range of values
    Minimum:341.279869
    Maximum:42175.631383
    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)
    • Rachel E. Henderson
    • Meredith G. Kratzmann
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Rachel E. Henderson
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    rehenderson@usgs.gov

Why was the data set created?

This dataset includes a reference baseline used by the Digital Shoreline Analysis System (DSAS) to calculate rate-of-change statistics for the coast of Long Island Sound, from Orient Point, New York, around the Sound coastline to the Connecticut/Rhode Island border. The baseline layer serves as the starting point for orthogonally-oriented transects generated by the DSAS application. The transects intersect each shoreline and establish measurement points used to calculate shoreline change 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: 2024 (process 1 of 4)
    A baseline was constructed with respect to the time series of shoreline positions using standard editing tools in ArcGIS Pro v3.5.57366. The offshore baseline was positioned to conform to the overall orientation of the shorelines alongshore. This was done so that the transects, which are generated by DSAS from the baseline, would intersect roughly perpendicular to the general trend of the shorelines. Unless otherwise noted, process steps were performed by Rachel E. Henderson. Person who carried out this activity:
    Rachel E. Henderson
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    rehenderson@usgs.gov
    Date: 2025 (process 2 of 4)
    The baseline shapefile was imported into a personal geodatabase in ArcCatalog v8.2 by right-clicking on the geodatabase > Import for use with the Digital Shoreline Analysis System (DSAS) software to perform rate calculations.
    Date: 2025 (process 3 of 4)
    The baseline feature class was exported from a personal geodatabase to a shapefile in ArcCatalog v8.2 by performing a right-mouse click on the data layer > export > to shapefile (single).
    Date: 2025 (process 4 of 4)
    The baseline shapefile was projected in ArcGIS Pro v3.5.57366 > Geoprocessing > Data Management Tools > Project. Parameters: input projection - UTM zone 18N NAD 83; output projection- geographic coordinates (WGS 84); transformation = WGS_1984_(ITRF00)_To_NAD_1983. Person who carried out this activity:
    Meredith G. Kratzmann
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    mkratzmann@contractor.usgs.gov
  3. What similar or related data should the user be aware of?
    Himmelstoss, Emily A., Farris, Amy S., Henderson, Rachel E., Kratzmann, Meredith G., Ergul, Ayhan, Zhang, Ouya, Zichichi, Jessica L., and Thieler, E. Robert, 2021, 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 link to access the version of the software used (v5.1). The second link is to the current version of DSAS (v6.x). The third link directs to the DSAS project page.
    Himmelstoss, Emily A., Henderson, Rachel E., Kratzmann, Meredith G., and Farris, Amy S., 2021, Digital Shoreline Analysis System (version 5.1) User Guide: Open-File Report 2021-1091, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Use the first link to access the user guide. The second link directs to the DSAS project page.

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

  1. How well have the observations been checked?
    The attributes in this layer are based on the requirements for use within DSAS.
  2. How accurate are the geographic locations?
    The baseline serves as a reference point for transects cast by DSAS. It does not correspond to any real-world feature.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This baseline file is complete and contains the baseline segment(s) used to cast transects along sections of the coastal region where shoreline position data were available.
  5. How consistent are the relationships among the observations, including topology?
    Each polyline has a unique identification attribute (ID). This field is used by the DSAS to designate the alongshore order of baselines, if more than one baseline exists.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints No access constraints. Please see 'Distribution Information' for details.
Use_Constraints These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.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 - 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 baselines used for the analysis of shoreline data (SHP and other shapefile components), browse graphic, and the FGDC CSDGM metadata.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data are available in a polyline shapefile format. The user must have software to read and process the data components of a shapefile.

Who wrote the metadata?

Dates:
Last modified: 22-Sep-2025
Metadata author:
Meredith G. Kratzmann
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
USA

508-548-8700 (voice)
508-457-2310 (FAX)
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.
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_P1TKEDFX/LIS_baseline_metadata.faq.html>
Generated by mp version 2.9.51 on Wed Sep 24 10:44:33 2025