Alabama: intersect points used in short-term (ST) shoreline change analysis

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Frequently anticipated questions:

What does this data set describe?

Title:
Alabama: intersect points used in short-term (ST) shoreline change analysis
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 Geographic Information System (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. 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.
  1. How might this data set be cited?
    Kratzmann, Meredith G., 20260622, Alabama: intersect points used in short-term (ST) shoreline change analysis: data release DOI:10.5066/P1JE2KSO, 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.

    Kratzmann, Meredith G., Farris, Amy S., and Weber, Kathryn M., 2026, National Shoreline Change—A GIS compilation of vector shorelines and associated shoreline change data from the 1800s to the 2020s for the coast of Alabama: data release DOI:10.5066/P1JE2KSO, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    suggested citation: Kratzmann, M.G., Farris, A.S., and Weber, K.M., 2026, National Shoreline Change—A GIS compilation of vector shorelines and associated shoreline change data from the 1800s to the 2020s for the coast of Alabama: U.S. Geological Survey data release, https://doi.org/10.5066/P1JE2KSO.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.345134
    East_Bounding_Coordinate: -87.518560
    North_Bounding_Coordinate: 30.280008
    South_Bounding_Coordinate: 30.219309
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/69e2b0c4b66b0195694c11ef?name=AL_intersects_ST.png&allowOpen=true (PNG)
    Map view of data. Pink dots indicate the extent of the short-term (decadal-scale) shoreline intersect points for Alabama.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2026
    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 (17530)
    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?
    AL_intersects_ST.shp
    The intersection points are generated by DSAS where each DSAS-generated transect crosses a shoreline. The points were used to compute short-term shoreline change rates in Alabama. (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Feature type.
    transorder
    Number assigned by DSAS based on the ordering of transects from baseline start to baseline end. (Source: U.S. Geological Survey)
    Range of values
    Minimum:7
    Maximum:1819
    baselineid
    Values in this field correlate to the baseline attribute field DSAS_ID and are assigned by DSAS to identify the baseline segment used to generate the measurement transect. Baseline segments assigned an ID = 0 are ignored by DSAS and no transects will be cast along those line segments. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:4
    shoreline0
    Date of shoreline position; date of survey as determined from shoreline layer. Text field. (Source: U.S. Geological Survey) Date of the shoreline in MM/DD/YYYY
    decimalye0
    Date of shoreline position in decimal year format. A decimal year is a representation of time expressed as the year plus the time elapsed since the beginning of the year as a fraction of the whole year. Since there are 365 days in one common year, a tenth of the common year is equal to 36.5 days (36 days and 12 hours). For example, the date 11/05/2019 is expressed as the decimal year 2019.846575. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1998.841096
    Maximum:2022.547945
    distance
    The distance in meters between the DSAS reference baseline and the shoreline intersection point along a DSAS transect. Negative decimal values indicate that the intersect point is located landward of the baseline. Positive decimal values indicate that the intersect point is located seaward of the baseline. (Source: U.S. Geological Survey)
    Range of values
    Minimum:-1386.73
    Maximum:-103.77
    Units:meters
    intersectx
    The X-coordinate location in eastings of the intersect point in NAD_1983_2011_UTM_Zone_16N. (Source: U.S. Geological Survey)
    Range of values
    Minimum:370564.591668
    Maximum:450127.073701
    Units:meters
    intersecty
    The Y-coordinate location in northings of the intersect point in NAD_1983_2011_UTM_Zone_16N. (Source: U.S. Geological Survey)
    Range of values
    Minimum:3343597.706555
    Maximum:3349926.352333
    Units:meters
    uncertain0
    The uncertainty of the shoreline position at the intersect point, as defined by the positional uncertainty attribute value (Uncy) of the shoreline dataset. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.99
    Maximum:7.60
    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with the intersects needed to calculate short-term (ST) shoreline change rates for Alabama. Please review the individual attribute descriptions for detailed information. All calculations for length are in meter units, NAD_1983_2011_UTM_Zone_16N.
    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)
    • 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: Meredith G. Kratzmann
    384 Woods Hole Road
    Woods Hole, MA
    USA

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

Why was the data set created?

Point data were created at the intersection of shoreline and transect locations during rate calculation by the Digital Shoreline Analysis System (DSAS) version 6.1 for the Alabama coastal region. A subset of the shoreline data (1998-2022) were used to calculate short-term (decadal-scale) change rates. Orthogonal transects cast by DSAS from a reference baseline intersect the shorelines, and the intersect data provide location and date information used to calculate rates of change. These point data contain identifiers related to the DSAS transect (transorder), baseline (baselineid), and the shoreline (shoreline0 [date], decimalye0 [date in decimal year format]). Coordinates and uncertainty information are also included in the intersect point file.

How was the data set created?

  1. From what previous works were the data drawn?
    AL_baseline (source 1 of 2)
    Kratzmann, Meredith G., 2026, Alabama: baseline generated to calculate shoreline change rates in Kratzmann, M.G., Farris, A.S., and Weber, K.M., 2026, National Shoreline Change—A GIS compilation of vector shorelines and associated shoreline change data from the 1800s to the 2020s for the coast of Alabama: U.S. Geological Survey data release, https://doi.org/10.5066/P1JE2KSO: data release DOI:10.5066/P1JE2KSO, U.S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details:
    The first link is to the larger work, the second link is to the baseline dataset.
    Type_of_Source_Media: digital data
    Source_Contribution:
    Baseline segments for Alabama (part of this same data release https://doi.org/10.5066/P1JE2KSO) are used by DSAS to cast measurement transects.
    AL_shorelines (source 2 of 2)
    Kratzmann, Meredith G., and Farris, Amy S., 2026, Alabama: shorelines (1849-2022) used to calculate shoreline change rates in Kratzmann, M.G., Farris, A.S., and Weber, K.M., 2026, National Shoreline Change—A GIS compilation of vector shorelines and associated shoreline change data from the 1800s to the 2020s for the coast of Alabama: U.S. Geological Survey data release, https://doi.org/10.5066/P1JE2KSO: data release DOI:10.5066/P1JE2KSO, U.S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details:
    The first link is to the larger work, the second link is to the shorelines dataset.
    Type_of_Source_Media: digital data
    Source_Contribution:
    Shoreline data for Alabama (part of this same data release https://doi.org/10.5066/P1JE2KSO). A subset of these shorelines (1998-2022) was used for short-term rate calculations.
  2. How were the data generated, processed, and modified?
    Date: 2026 (process 1 of 5)
    Overview of the workflow used to calculate shoreline change rates and intersection points as part of the shoreline change analysis using DSAS v6.1: 1) Transects were generated at 50-meter spacing using a manually created baseline and shorelines compiled for Alabama (see source citations in the shorelines metadata file); 2) Manual edits to transects performed; 3) Transects and shorelines were used to generate intersection points and calculate rates of change. The following process steps describe these actions.
    For more details on the DSAS software, please visit: https://www.usgs.gov/centers/whcmsc/science/digital-shoreline-analysis-system-dsas
    This and the following process steps were performed by the same person: Meredith Kratzmann. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Meredith Kratzmann
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    Date: 2026 (process 2 of 5)
    DSAS v6.1 was used to create transect features using the baseline and shorelines shapefiles for Alabama. Input parameters: shoreline layer = Shorelines_AL, baseline layer= Baseline_AL, transect spacing= 50 meters, transect length= 1500 meters, smoothing distance= 2000 meters, clip transects to shoreline extent= unchecked. File produced= AL_transects_ALL. Some transects were manually edited for length, moved, or deleted in an edit session using standard editing tools in ArcGIS Pro 3.5.5. Edited transect shapefile was renamed= AL_transects. Data sources used in this process:
    • Baseline_AL
    • Shorelines_AL
    Data sources produced in this process:
    • AL_transects
    Date: 2026 (process 3 of 5)
    To calculate short-term (ST) shoreline change rates, Alabama lidar-derived shorelines from 1998 to 2022 were utilized with the DSAS-generated transects to create shoreline intersect points and perform rate calculations. Input parameters: shoreline layer= Shorelines_AL, transects layer= AL_transects, date range= 1998 to 2022, shoreline intersection threshold= 2, calculate= EPR (end point rate), LRR (linear regression rate), NSM (net shoreline movement), SCE (shoreline change envelope), confidence interval=90%, create DSAS summary report= checked. Files produced= al_transects_intersect_20260114_141953, al_transects_rates_20260114_141953. Any null values are represented in the attribute table of the rates layer as 9999.99. Data sources used in this process:
    • Shorelines_AL
    • AL_transects
    • AL_bias
    Data sources produced in this process:
    • al_transects_intersect_20260114_141953
    • al_transects_rates_20260114_141953
    Date: 2026 (process 4 of 5)
    The intersect point layer was exported from DSAS using the Export Data tool and renamed= AL_intersects_ST. Data sources used in this process:
    • al_transects_intersect_20260114_141953
    Data sources produced in this process:
    • AL_intersects_ST
    Date: 2026 (process 5 of 5)
    The intersects shapefile was projected in ArcGIS Pro v3.5.5 > Geoprocessing > Data Management Tools > Projections and Transformations > Project. Parameters: Input Coordinate System - NAD_1983_2011_UTM_Zone_16N; Output Coordinate System - GCS_WGS_1984; transformation = WGS_1984_(ITRF08)_To_NAD_1983_2011.
  3. What similar or related data should the user be aware of?
    Henderson, Rachel E., Farris, Amy S., Kratzmann, Meredith G., Bartlett, Marie K., Ergul, Ayhan, McAndrews, John, Cibaj, Raison, Zichichi, Jessica L., Himmelstoss, Emily A., and Thieler, E. Robert, 2026, Digital Shoreline Analysis System version 6.1: software release version 6.1.177, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Use the first link to access the publication page. The second link is to the current version of DSAS (v6.1). The third 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 of this dataset are based on the field requirements of the Digital Shoreline Analysis System and were automatically generated by the software during creation of the intersect points layer.
  2. How accurate are the geographic locations?
    The intersect points represent the location where transects cast by the DSAS software cross a historical shoreline position. The points can be used to visually display which shorelines were used in the rate calculation and capture details on the shoreline represented at the intersection. The distances between the reference baseline and each shoreline intersection along a transect are used by the DSAS software to compute the shoreline change metrics.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This dataset contains all shoreline/transect intersect points used to compute shoreline change rates in the DSAS software application.
  5. How consistent are the relationships among the observations, including topology?
    These data were generated using DSAS, an automated software program, which does not perform checks for fidelity of the input features. Following generation of the rates and intersects by the DSAS software a visual inspection of the intersects was performed in map view to determine that no measurements were included that did not have a corresponding transect for the shoreline change analysis.

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. These data were automatically generated using the DSAS v6.1 software application. 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)
  2. What's the catalog number I need to order this data set? The dataset contains the point intersections 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.
  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 point 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-Jun-2026
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)
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_P1JE2KSO/AL_intersects_ST_metadata.faq.html>
Generated by mp version 2.9.51 on Mon Jun 22 16:21:27 2026