Meredith G. Kratzmann 20260622 1.0 vector digital data data release DOI:10.5066/P1JE2KSO Woods Hole Coastal and Marine Science Center, Woods Hole, MA U.S. Geological Survey, Coastal and Marine Hazards and Resources Program https://doi.org/10.5066/P1JE2KSO https://www.sciencebase.gov/catalog/item/69e2b090b66b0195694c11ed Meredith G. Kratzmann Amy S. Farris Kathryn M. Weber 2026 1.0 vector digital data data release DOI:10.5066/P1JE2KSO Reston, VA U.S. Geological Survey 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. https://doi.org/10.5066/P1JE2KSO https://www.sciencebase.gov/catalog/item/69e2a7d5b66b0195694c1197 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. 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. Orthogonal transects cast by DSAS from a reference baseline intersect the shorelines, and the intersect data provide location and date information used to calculate long-term (century-scale) 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, uncertainty, and bias information are also included in the intersect point file. 2026 publication date Complete None planned -88.333247 -87.518560 30.281325 30.220701 ISO 19115 Topic Category oceans environment geoscientificInformation None Intersects Intersect points Shoreline change Digital Shoreline Analysis System DSAS U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Woods Hole Coastal and Marine Science Center WHCMSC USGS Thesaurus geospatial datasets coastal processes USGS Metadata Identifier USGS:69e2b090b66b0195694c11ed GNIS State of Alabama Dauphin Island Fort Morgan Alabama Gulf Shores None Gulf Coast Bon Secour National Wildlife Refuge United States of America North America No access constraints. Please see 'Distribution Information' for details. 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. U.S. Geological Survey Meredith G. Kratzmann mailing and physical

384 Woods Hole Road

Woods Hole MA 02543-1598 USA 508-548-8700 508-457-2310 mkratzmann@contractor.usgs.gov https://www.sciencebase.gov/catalog/file/get/69e2b090b66b0195694c11ed?name=AL_intersects_LT.png&allowOpen=true Map view of data. Green dots indicate the extent of the long-term (century-scale) shoreline intersect points for Alabama. PNG Microsoft Windows 11 Enterprise; Esri ArcGIS Pro 3.5.5 Rachel E. Henderson Amy S. Farris Meredith G. Kratzmann Marie K. Bartlett Ayhan Ergul John McAndrews Raison Cibaj Jessica L. Zichichi Emily A. Himmelstoss E. Robert Thieler 2026 publication software release version 6.1.177 Reston, VA U.S. Geological Survey 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. https://doi.org/10.5066/P1NHMJNC https://code.usgs.gov/cch/dsas https://www.usgs.gov/centers/whcmsc/science/digital-shoreline-analysis-system-dsas 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. 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. This dataset contains all shoreline/transect intersect points used to compute shoreline change rates in the DSAS software application. 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. Meredith G. Kratzmann 2026 1.0 vector digital data data release DOI:10.5066/P1JE2KSO Woods Hole Coastal and Marine Science Center, Woods Hole, MA U.S. Geological Survey The first link is to the larger work, the second link is to the baseline dataset. https://doi.org/10.5066/P1JE2KSO https://www.sciencebase.gov/catalog/item/69e2afc2b66b0195694c11e3 digital data 2026 publication date AL_baseline Baseline segments for Alabama (part of this same data release https://doi.org/10.5066/P1JE2KSO) are used by DSAS to cast measurement transects. Meredith G. Kratzmann Amy S. Farris 2026 1.0 vector digital data data release DOI:10.5066/P1JE2KSO Woods Hole Coastal and Marine Science Center, Woods Hole, MA U.S. Geological Survey The first link is to the larger work, the second link is to the shorelines dataset. https://doi.org/10.5066/P1JE2KSO https://www.sciencebase.gov/catalog/item/69e2b013b66b0195694c11e7 digital data 2026 ground condition AL_shorelines Shoreline data for Alabama (part of this same data release https://doi.org/10.5066/P1JE2KSO). Meredith G. Kratzmann Amy S. Farris 2026 1.0 vector digital data data release DOI:10.5066/P1JE2KSO Woods Hole Coastal and Marine Science Center, Woods Hole, MA U.S. Geological Survey The first link is to the larger work, the second link is to the bias feature dataset. https://doi.org/10.5066/P1JE2KSO https://www.sciencebase.gov/catalog/item/69e2b0f0b66b0195694c11f1 digital data 2026 publication date AL_bias Bias feature for Alabama (part of this same data release https://doi.org/10.5066/P1JE2KSO) used by DSAS to calculate rates that account for the offset between proxy-based HWL/WDL (wet dry line) and datum-based MHW shorelines. 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. 2026 U.S. Geological Survey Meredith Kratzmann Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543 508-548-8700 508-457-2310 mkratzmann@contractor.usgs.gov 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. Baseline_AL Shorelines_AL 2026 AL_transects To calculate long-term (LT) shoreline change rates, Alabama shorelines from 1849 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, bias feature= AL_bias, date range= full range (all shorelines), 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. Shapefiles produced= al_transects_intersect_20260114_141331, al_transects_rates_20260114_141331. Shorelines_AL AL_transects AL_bias 2026 al_transects_intersect_20260114_141331 al_transects_rates_20260114_141331 The intersect point layer was exported from DSAS using the Export Data tool and renamed= AL_intersects_LT. al_transects_intersect_20260114_141331 2026 AL_intersects_LT 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. 2026 Vector String 27402 0.0000001 0.0000001 Decimal degrees WGS_1984 WGS_1984 6378137.000000 298.257224 AL_intersects_LT.shp The intersection points are generated by DSAS where each DSAS-generated transect crosses a shoreline. The points were used to compute long-term shoreline change rates in Alabama. U.S. Geological Survey FID Internal feature number. Esri Sequential unique whole numbers that are automatically generated. Shape Feature geometry. Esri Feature type. transorder Number assigned by DSAS based on the ordering of transects from baseline start to baseline end. U.S. Geological Survey 37 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. U.S. Geological Survey 1 4 shoreline0 Date of shoreline position; date of survey as determined from shoreline layer. Text field. 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. U.S. Geological Survey 1849.498630 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. U.S. Geological Survey -1453.81 -103.77 meters intersectx The X-coordinate location in eastings of the intersect point in NAD_1983_2011_UTM_Zone_16N. U.S. Geological Survey 371702.276286 450127.073701 meters intersecty The Y-coordinate location in northings of the intersect point in NAD_1983_2011_UTM_Zone_16N. U.S. Geological Survey 3343684.405995 3350074.637824 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. U.S. Geological Survey 0.99 13.00 dsas_type Shoreline type field used to specify the shoreline proxy or datum to which the shoreline (at the intersection point) is referenced. U.S. Geological Survey MHW Mean High Water (datum-based shoreline). U.S. Geological Survey HWL High Water Line (proxy-based shoreline). U.S. Geological Survey WDL Wet-Dry Line (proxy-based shoreline). U.S. Geological Survey bias_x The X coordinate of the intersect point with the bias applied, NAD_1983_2011_UTM_Zone_16N. U.S. Geological Survey 371702.276286 450127.073701 meters bias_y The Y coordinate of the intersect point with the bias applied, NAD_1983_2011_UTM_Zone_16N. U.S. Geological Survey 3343679.938298 3350069.973385 meters bias The proxy-datum bias value describing the unidirectional horizontal offset (in meters) between the MHW elevation of the lidar data and HWL shoreline proxy position. U.S. Geological Survey 4.33 5.99 meters bias_dist0 The distance in meters along the transect from the baseline to the intersect point, with the proxy-datum bias applied. U.S. Geological Survey -1449.07 -103.77 meters bias_unce0 The uncertainty in the position of the HWL associated with the calculated proxy-datum bias value. U.S. Geological Survey 0.99 13.00 The entity and attribute information provided here describes the tabular data associated with the intersect points needed to calculate long-term 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. U.S. Geological Survey U.S. Geological Survey - GS ScienceBase mailing and physical address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov 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. 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. Shapefile ArcGIS Pro version 3.5.5 Esri point shapefile (compressed to ZIP format) These files (.cpg, .dbf, .prj, .sbn, .sbx, .shp, .html, 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 and include FGDC CSDGM-compliant metadata in HTML format. Transfer size is in MB. Unzip 1.56 https://doi.org/10.5066/P1JE2KSO https://www.sciencebase.gov/catalog/item/69e2b090b66b0195694c11ed https://www.sciencebase.gov/catalog/file/get/69e2b090b66b0195694c11ed The first link is to the USGS publication page, the second link is to the dataset page, and the third link downloads the data. None These data are available in a point shapefile format. The user must have software to read and process the data components of a shapefile. 20260622 Meredith G. Kratzmann U.S. Geological Survey mailing and physical address

384 Woods Hole Road

Woods Hole MA 02543-1598 USA 508-548-8700 508-457-2310 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the person is no longer with USGS. FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time