Historical Shorelines for Puerto Rico from 1901 to 1987

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Frequently anticipated questions:

What does this data set describe?

Title: Historical Shorelines for Puerto Rico from 1901 to 1987
Abstract:
The U.S. Geological Survey (USGS) maintains shoreline positions for the United States coasts from both older sources, such as aerial photos or topographic surveys, as well as contemporary sources like lidar point clouds and digital elevation models (DEMs). These shorelines are compiled and analyzed in the Digital Shoreline Analysis System (DSAS) software to compute rates of change. It is useful to keep a record of historical shoreline positions as a method of monitoring change over time to identify areas most susceptible to erosion or accretion. These data can help coastal managers understand which areas of the coast are vulnerable.
This data release and other associated products represent an expansion of the USGS national-scale shoreline database to include Puerto Rico and its islands, Vieques and Culebra. The United States Geological Survey (USGS) in cooperation with the Coastal Research and Planning Institute of Puerto Rico (CoRePI, part of the Graduate School of Planning at the University of Puerto Rico, Rio Piedras Campus) has derived and compiled a database of historical shoreline positions using a variety of methods. These shorelines are used to measure the rate of shoreline change over time.
  1. How might this data set be cited?
    U.S. Geological Survey, 20211117, Historical Shorelines for Puerto Rico from 1901 to 1987: data release DOI:10.5066/P9CLXCEG, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    suggested citation: Heslin, J.L., Henderson, R.E., Himmelstoss, E.A., 2021, Historical Shorelines for Puerto Rico from 1901 to 1987: U.S. Geological Survey data release, https://doi.org/10.5066/P9CLXCEG.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -67.2714
    East_Bounding_Coordinate: -65.4403
    North_Bounding_Coordinate: 18.5161
    South_Bounding_Coordinate: 17.9131
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/60cb7627d34e86b938a3a1b0?name=PR_1901-1987_Shorelines.jpg (JPEG)
    Map view of data
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Jul-1901
    Ending_Date: 25-Feb-1987
    Currentness_Reference:
    ground condition
  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 (624)
    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 0.0198254503. Longitudes are given to the nearest 0.0207092681. Latitude and longitude values are specified in Decimal seconds. 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?
    PR_Historical_Shorelines.shp Attribute Table
    Table containing attribute information associated with the dataset. (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.
    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 were 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: U.S. Geological Survey)
    Range of values
    Minimum:07/01/1901
    Maximum:02/25/1987
    UNCY
    Estimate of shoreline position uncertainty. Actual shoreline position is within the range of this value (plus or minus, meters) of this value. The uncertainty was determined by the equation presented in the process steps. A default value of 9.25, which was the average reported uncertainty from OFR 93-574 (Thieler and Danforth, 1993), is applied for shorelines that do not have a reference image available. (Source: U.S. Geological Survey)
    Range of values
    Minimum:3.99
    Maximum:12.84
    PROXY
    Method used to determine the shoreline (Source: U.S. Geological Survey)
    ValueDefinition
    Wet/Dry LineThis is defined as the most recent swash line and is delineated as the boundary between the wet and dry beach. All aerial photo shorelines are wet/dry lines.
    HWLHigh Water Line. This is distinguished as the last high tide swash line, usually found more landward of the wet/dry line. All T-sheet shorelines are high water lines.
    SOURCE
    File name or registry number associated with the aerial photos or T-/TP-Sheets reference data. Some rows in this field may be left empty, which indicates that these shorelines were originally derived from OFR 93-574 (Thieler and Danforth, 1993) and no reference image available to verify the original source. (Source: U.S. Geological Survey) Alphanumeric identifier found printed on the corresponding aerial photo or T-/TP-Sheet.
    AGENCY
    The agency that provided the source data to create the shoreline. (Source: U.S. Geological Survey)
    ValueDefinition
    PRDRNDepartamento de Recursos Naturales (Department of Natural Resources), San Juan, Puerto Rico
    USDA-SCSU.S. Department of Agriculture - Soil Conservation Service, Salt Lake City, Utah
    USGS, PRDCU.S. Geological Survey, National Cartographic Information Center, Rockville, Maryland; Departamento de Carreteras (Department of Transportation), San Juan, Puerto Rico
    PRDCDepartamento de Carreteras (Department of Transportation), San Juan, Puerto Rico
    NOAANational Oceanic and Atmospheric Administration
    TYPE
    The type of source data used to create the shoreline (Source: U.S. Geological Survey)
    ValueDefinition
    Aerial PhotoAerial Photo
    NOS TP-SheetNational Oceanic Service topographic sheet, TP series
    NOS T-SheetNational Oceanic Service topographic sheet, T series
    YEAR
    The year of each shoreline feature as noted in the DATE_ field (Source: U.S. Geological Survey)
    Range of values
    Minimum:1901
    Maximum:1987

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?
    Julia L. Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-457-2230 (voice)
    jheslin@usgs.gov

Why was the data set created?

An interpreation of the original shoreline data, similar to what can be found in this data release, were part of a previously published Open File Report (OFR 93-574). The rates and images of the shoreline extents were published in this OFR but the shoreline shapefiles themselves were not published. This data release is an effort to recover, edit, and add to the existing shoreline data through a thorough quality assurance/quality control (QA/QC) workflow. Shorelines were digitized from georeferenced T-sheets and air photographs, using the high-water line and wet-dry line, respectively, as a shoreline reference. These data are used in conjunction with other shoreline files to calculate rates of shoreline change.

How was the data set created?

  1. From what previous works were the data drawn?
    OFR 93-574 (source 1 of 8)
    Thieler, E.R., and Danforth, W.W., 1993, Historical Shoreline Changes in Puerto Rico, 1901-1987: Open-File Report 93-574, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    Used shoreline shapefiles, quadrangles, T-sheets, and aerial photos referenced in the open file report (OFR). While the rates and images of the shoreline extents were published in an appendix of the OFR, the shapefiles themselves were previously unpublished.
    NOAA Georeferenced T-Sheets (source 2 of 8)
    National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey, 2020, NOAA Historical Surveys (T-Sheets): National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey, Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution: Used to QA/QC and redigitize historical shorelines.
    NOAA Non-Georeferenced T-Sheets (source 3 of 8)
    National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey, 2020, Non-georeferenced NOAA Shoreline Survey Scans website: National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey (NGS), Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution: Used to fill in gaps of T-sheet shorelines.
    NCAT (source 4 of 8)
    National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey (NGS), 202002, NGS Coordinate Conversion and Transformation Tool (NCAT): National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey (NGS), Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    Used to convert T-sheet coordinates from historical to updated datum.
    Geodetic Marks (source 5 of 8)
    National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey, 20200102, NGS Geodetic Marks Shapefile, Puerto Rico, 2020: National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey, Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    The triangulation stations in the shapefile were used to georeference T-sheets from 1901, which referenced an outdated datum.
    Orthophotos (source 6 of 8)
    United States Army Corps of Engineers (USACE), 20080217, 2006-2007 natural color orthophotos covering the islands of Puerto Rico, Culebra, Vieques, St. Thomas, St. John, and St. Croix: National Oceanic and Atmospheric Administration Office for Coastal Management (NOAA/OCM), 2234 South Hobson Ave, Charleston, SC 29405-2413.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Scale_Denominator: 2400
    Source_Contribution:
    These orthophotos were used as basemap imagery to help in georeferencing historic aerial photos. The accompanying tile index shapefile was used to identify necessary aerial photos to download.
    NOAA Tides and Currents (source 7 of 8)
    National Oceanic and Atmospheric Administration (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS), 2021, NOAA Tides and Currents: National Oceanic and Atmospheric Administration (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS), Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    Used to derive the average great diurnal tide range for Puerto Rico.
    2018 Lidar (source 8 of 8)
    Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX), 20190702, 2018 USACE FEMA Topobathy Lidar: Main Island, Culebra, and Vieques, Puerto Rico: National Oceanic and Atmospheric Administration Office for Coastal Management (NOAA/OCM), 2234 South Hobson Ave, Charleston, SC 29405-2413.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution: Used to derive the average beach slope for Puerto Rico.
  2. How were the data generated, processed, and modified?
    Date: 2020 (process 1 of 11)
    Original shoreline shapefiles and source data (including ungeoreferenced topographic sheets [T- or TP-sheets], aerial photos, and USGS quadrangles) from OFR 93-574, Historical Shoreline Changes in Puerto Rico, 1901-1987 (Thieler and Danforth, 1993), were acquired from the archives of internal USGS data. The shapefiles received were separated by year based on the corresponding source information.
    The first step of this QA/QC process was to make preliminary edits and additions to the original shoreline shapefiles. One of the first noticeable errors was the prevalence of duplicate features across the shorelines. For instance, identical features existed within the same shoreline shapefile, but each feature had its own unique attributes within the attribute table. To identify and delete these duplicate features, a "Length" field was added to each of the shapefiles. Using the Calculate Geometry tool within each shapefile's attribute table, the length of each shoreline feature was derived. With this new length field, a visual inspection the shapefiles' attribute tables with these identical shoreline lengths helped identify the duplicate shorelines.
    There were also instances where there were identical features across multiple shoreline feature classes. In this case, a visual inspection was made in ArcMap and the Select by Location tool was used to identify these duplicate shorelines. If the target layer (meaning the feature class that contained the incorrectly duplicated shoreline) was spatially identical to the source layer (the feature class with the correct shoreline), then those selected shorelines were reviewed and deleted.
    Each of these edited shapefiles was then exported as a feature class to a personal geodatabase for two reasons: for organizational purposes; and DSAS requires shorelines to be stored in a personal geodatabase (Himmelstoss and others, 2018). Fields that are necessary for the shoreline change analysis through DSAS as well as fields pertaining to other relevant information were added to each of the feature classes. These are described in the Attribute section of the metadata.
    The historical shorelines were then assessed based on their accuracy by georeferencing the source data from which they originated. Two different shoreline sources are referenced: T-sheets and aerial photos. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • OFR 93-574
    Data sources produced in this process:
    • Historical Shoreline Geodatabase
    Date: 2020 (process 2 of 11)
    The T-sheet shorelines were the first to be assessed. The T-sheets from OFR 93-574 (Thieler and Danforth, 1993) were cross-referenced with NOAA georeferenced T-sheets available through the NOAA Shoreline website (https://shoreline.noaa.gov/data/datasheets/t-sheets.html). Upon further investigation of NOAA's georeferenced T-sheets, original shoreline data, and Esri's World Imagery basemap all viewed together in ArcMap, there was a roughly 200-meter offset that existed in the georeferenced T-sheets from NOAA. This offset is likely due to a datum error. Most historical T-sheet surveys were conducted in the continental United States and reference the North American Datum of 1927. T-sheets in Puerto Rico, however, reference the Puerto Rico Datum of 1940. Therefore, we needed to georeference all T-sheets by using the non-georeferenced T-sheets.
    While most of these T-sheets were already acquired from the internal data transfer, a few T-sheets were searched for and replaced based on their quality (e.g. part of the T-sheet may have been clipped) using the Non-georeferenced NOAA Shoreline Survey Scans website (https://nosimagery.noaa.gov/images/shoreline_surveys/survey_scans/NOAA_Shoreline_Survey_Scans.html). A total of 31 T-sheets were included from the original OFR and used to validate shorelines. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey, NORTHEAST REGION
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • OFR 93-574
    • NOAA Georeferenced T-Sheets
    • NOAA Non-Georeferenced T-Sheets
    • Historical Shoreline Geodatabase
    Date: 2020 (process 3 of 11)
    After all T-sheets were acquired, additional T-sheets adjacent to the original T-sheets were also acquired. To locate these additional T-sheets, an index to adjoining T-sheets on the bottom left of each T-sheet was used. The T-sheets were downloaded from the Non-georeferenced NOAA Shoreline Survey Scans website. 27 additional T-sheets were used to add to the existing shoreline data.
    Some of these additional T-sheets from 1966 were only available as PiCture eXchange (PCX) image files, which are not compatible with ArcMap. These files were converted from PCX to TIF files using GIMP software (version 2.10.22, https://www.gimp.org/), an open-source graphics editor. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • NOAA Non-Georeferenced T-Sheets
    Date: 2020 (process 4 of 11)
    T-sheets dating from 1959 and beyond in this dataset were georeferenced using the NGS Coordinate Conversion and Transformation Tool (NCAT, https://geodesy.noaa.gov/NCAT/) and ArcMap. After opening up an ArcMap document, the data frame's coordinate system was set to NAD 1983 StatePlane Puerto Rico Virgin Isl FIPS 5200 (Meters). Each non-georeferenced T-sheet was added to the ArcMap document.
    Eight well distributed control points were selected using the coordinates indicated along the edges of the T-sheets. These coordinates were transformed using the NCAT Tool from the Puerto Rico datum (PR40) to the North American Datum of 1983 (NAD83) Puerto Rico State Plane Coordinate System. After the eight control points were georegistered, adding or removing control points from the link table was considered to obtain an optimal root mean square error (RMSE). No less than six control points were used to georeference each of these T-sheets. It is important to note that the RMSE conforms to the National Map Accuracy Standards. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • NCAT
    Data sources produced in this process:
    • Georeferenced T-Sheets, 1959-1980
    Date: 2020 (process 5 of 11)
    In this dataset, T-sheets from 1901 needed to be georeferenced using a different method than the relatively newer T-sheets. These T-sheets reference an older Puerto Rico datum that was not available for conversion through the NCAT tool. These older T-sheets include triangulation stations which can also be used in the georeferencing process.
    Locations of these triangulation stations were determined by using a shapefile of NGS known geodetic marks in Puerto Rico (https://geodesy.noaa.gov/cgi-bin/sf_archive.prl). This shapefile was projected to NAD 1983 StatePlane Puerto Rico Virgin Isl FIPS 5200 (Meters). Then, the non-georeferenced T-sheets were georeferenced by matching the name of the triangulation station to the name of the geodetic mark ("NAME" field) in the shapefile's attribute table. If there were multiple geodetic marks by the same name, the fields "FIRST_RECV" and "LAST_RECV," which indicate the years that the geodetic mark was first observed and last recovered, respectively, were used to select the appropriate mark based on the time frame. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • Geodetic Marks
    Data sources produced in this process:
    • Georeferenced T-Sheets, 1901
    Date: 2020 (process 6 of 11)
    After all T-sheets were georeferenced, a visual inspection in ArcMap determined further edits that needed to be made to the shoreline features.
    Some of the features contained errors as a result of the software that was used to digitize the original shorelines (Thieler and Danforth, 1993). There were a series of clustered vertices and rough, jagged edges within some shoreline features that required deletion. These were likely artifacts of the digitizing track mode that may have inadvertently added erroneous vertices not reflective of the shoreline.
    There were also errors regarding the alignment of the shoreline features to the georeferenced T-sheets. In some cases, the digitized shoreline did not line up with the shoreline delineated on the T-sheets. In other cases, there were T-sheet shoreline features that were omitted from the digitized shoreline as they may have been cut off when stitching together overlapping T-sheets.
    Based on this assessment, it was determined that the majority of these shorelines would be re-digitized. In a few instances, only the vertices from the digitized shorelines were adjusted to match the shoreline delineated on the T-sheet as there was little spatial discrepancy between the digitized shoreline and the georeferenced T-sheet. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • Georeferenced T-Sheets 1959-1980
    • Georeferenced T-Sheets 1901
    • Historical Shoreline Geodatabase
    Data sources produced in this process:
    • Updated T-Sheet Shoreline Feature Classes
    Date: 2021 (process 7 of 11)
    The next shoreline features to be QA/QC'd were the aerial photo shorelines. Unlike the T-sheets, the control points for the aerial photos were established using orthorectified imagery downloaded from the NOAA Data Access Viewer (DAV, https://coast.noaa.gov/dataviewer/#/imagery/search/where:ID=394). In an effort to reduce the uncertainty values for the aerial photos, natural color orthophotos were used as opposed to the quadrangles mentioned in the OFR (Thieler and Danforth, 1993).
    Like the T-sheets, the aerial photos were acquired through an internal data transfer. These aerial photos were not georeferenced but were separated by municipality and year. The aerial photos were georeferenced using ArcMap. In the ArcMap document, the data frame's coordinate system was set to match the shoreline data (NAD 1983 StatePlane Puerto Rico Virgin Isl FIPS 5200 (Meters)). In order to retrieve the corresponding natural color orthophoto, a few data sources were needed.
    First, even though the quadrangles were not used directly in the georeferencing process, they were used to help locate the general vicinity of the aerial photos. The quadrangles were georeferenced using the same method as the T-sheets as the quadrangles contained latitude and longitude points in the Puerto Rico datum of 1940 (see Step 4).
    Then, the tile index shapefile downloaded from the bulk download page on the NOAA DAV (https://chs.coast.noaa.gov/htdata/raster1/imagery/PuertoRico_RGB_2007_394/) was brought into the ArcMap document. The tiles from this shapefile contained the associated orthophoto direct download link. These along with the Esri basemap imagery helped determine the approximate location of the non-georeferenced aerial photos.
    The aerial photos were georeferenced using consistent ground points available in the orthophotos (e.g. road intersections, man-made structures, rocks along the shoreline). At least four ground control points for a first order polynomial transformation and at least six points for a second order polynomial transformation were selected for each of the aerial photos to achieve an acceptable RMSE. It is important to note that the RMSE conforms to the National Map Accuracy Standards. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • OFR 93-574
    • Orthophotos
    Data sources produced in this process:
    • Georeferenced Aerial Photos, 1936-1987
    • Georeferenced Quadrangles
    Date: 2021 (process 8 of 11)
    After all available aerial photos were georeferenced, a visual inspection in ArcMap determined further edits that needed to be made to the shoreline features.
    Some of the features contained errors as a result of the software that was used to digitize these original shorelines (Thieler and Danforth, 1993). There were a series of clustered vertices and rough, jagged edges within some shoreline features that would require deletion. These were likely artifacts of the digitizing track mode that may have inadvertently added erroneous vertices not reflective of the shoreline.
    Based on this assessment, it was determined that many of these shorelines would be re-digitized. In some instances, only the vertices from the digitized shorelines were adjusted to match the shoreline delineated on the aerial photo as there was little spatial discrepancy between the digitized shoreline and the georeferenced aerial photo. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • Georeferenced Aerial Photos, 1936-1987
    • Historical Shoreline Geodatabase
    Data sources produced in this process:
    • Updated Aerial Photo Shoreline Feature Classes
    Date: 2021 (process 9 of 11)
    Additional fields that were added to the attribute table needed to be calculated. All fields except "UNCY" were calculated using information provided in the OFR or directly from the source itself. The uncertainty calculations were largely adapted from the uncertainty equations created by Fletcher and others 2012.
    The following summation in quadrature equation was used to calculate the uncertainty for the T-sheet shorelines:
    Sqr(([U_SURVEY]^2) + (([U_CELL_SIZE] * [U_RMSE])^2) + ([U_CELL_SIZE]^2) + ([U_DIGITIZE]^2) + ([U_SHORE]^2))
    where U_SURVEY = error associated with the T-sheet survey (10 meters for T-sheets before the year 1960, 3 meters after 1960; see Shalowitz, 1964), U_CELL_SIZE = the pixel cell size of each rectified T-sheet, U_RMSE = the unitless root mean square error value of each T-sheet recorded from the georeferencing link table, U_DIGITIZE = the maximum error associated with digitizing as represented in past studies (1 meter; see Hapke and others, 2010), U_SHORE = the estimated uncertainty in the shoreline position due to the fact that the high water line varies with tide. U_SHORE was estimated to be 3 meters and was derived by taking the average great diurnal tide range (or the difference between mean higher high water and mean lower low water) and dividing it by the average beach slope. The tide range values were taken from six well-distributed tide stations from NOAA Tides and Currents (https://tidesandcurrents.noaa.gov/). The average beach slope was calculated using the average slope value from the 2018 Lidar data. Dividing the great diurnal tide range (an approximation of the water level's vertical range) by the average beach slope (represented as rise/run) yields the horizontal range of where the water meets the beach. It is presumed that the shoreline proxies derived from historical sources will fall within this horizontal range, thus an appropriate value to apply to the uncertainty equation.
    The following summation in quadrature equation was used to calculate the uncertainty for the aerial photo shorelines:
    Sqr(([U_AIR_PHOTO] ^2) + ([U_BASEMAP] ^2) + (([U_CELL_SIZE]* [U_RMSE])^2) + ([U_CELL_SIZE]^2) + ([U_DIGITIZE]^2) + ([U_SHORE]^2))
    where U_AIR_PHOTO = the average aerial photo error due to distortion and cartographic error (3 meters; see Crowell and others, 1991), U_BASEMAP = the horizontal accuracy from the orthophotos' metadata (5 meters), U_CELL_SIZE = the pixel cell size of each rectified aerial photo, U_RMSE = the unitless root mean square error value of each aerial photo recorded from the georeferencing link table, U_DIGITIZE = the maximum error associated with digitizing as represented in past studies (1 meter; see Hapke and others, 2010), U_SHORE = the estimated uncertainty in the shoreline position due to the fact that the wet/dry line varies with tide. U_SHORE was estimated to be 3 meters.
    While all T-sheets were available to cross-reference with the original digitized shorelines, only a sample of the aerial photos were available for the QA/QC. In the event that there was not an aerial photo available for a digitized shoreline, the originally reported uncertainty value from the OFR (9.25 meters) was left as the uncertainty value. Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • NOAA Tides and Currents
    • 2018 Lidar
    • Orthophotos
    • Updated T-Sheet Shoreline Feature Classes
    • Updated Aerial Photo Shoreline Feature Classes
    Data sources produced in this process:
    • T-Sheet Shorelines with Attributes
    • Aerial Photo Shorelines with Attributes
    Date: 2021 (process 10 of 11)
    After all the individual shoreline feature classes within the personal geodatabase were evaluated a final time, they were exported as shapefiles and merged together into one shapefile (ArcToolbox >> Data Management >> General >> Merge). Person who carried out this activity:
    Julia L Heslin
    U.S. Geological Survey
    Geographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-457-2262 (voice)
    508-457-2310 (FAX)
    jheslin@usgs.gov
    Data sources used in this process:
    • T-Sheet Shorelines with Attributes
    • Aerial Photo Shorelines with Attributes
    Data sources produced in this process:
    • Merged Historical Shorelines Shapefile
    Date: 2021 (process 11 of 11)
    The data were projected to WGS 84 using ArcToolbox >> Data Management Tools >> Projections and Transformations >> Feature >> Project (Parameters: Input Coordinate System = NAD_1983_StatePlane_Puerto_Rico_Virgin_Isl_FIPS_5200; Output Coordinate System = GCS_WGS_1984; Geographic Transformation = Puerto_Rico_To_NAD_1983 + Puerto_Rico_To_WGS_1984_4). Data sources used in this process:
    • Merged Historical Shorelines Shapefile
    Data sources produced in this process:
    • PR_Historical_Shorelines
  3. What similar or related data should the user be aware of?
    Thieler, E.R., and Danforth, W.W., 1993, Historical Shoreline Changes in Puerto Rico, 1901-1987: Open-File Report 93-574, U.S. Geological Survey, Reston, VA.

    Online Links:

    Himmelstoss, Emily A., Henderson, Rachel E., Kratzmann, Meredith G., and Farris, Amy S., 2018, Digital Shoreline Analysis System (DSAS) Version 5.0 User Guide: Open-File Report 2018-1179, U.S. Geological Survey, Reston, VA.

    Online Links:

    Fletcher, Charles H., Romine, Bradley M., Genz, Ayesha S., Barbee, Matthew M., Dyer, Matthew, Anderson, Tiffany R., Lim, S. Chyn, Vitousek, Sean, Bochicchio, Christopher, and Richmond, Bruce M., 2012, National assessment of shoreline change: Historical shoreline change in the Hawaiian Islands: Open-File Report 2011-1051, U.S. Geological Survey, Reston, VA.

    Online Links:

    Shalowitz, Aaron L., 1964, Shore and Sea Boundaries: With Special Reference to the Interpretation and Use of Coast and Geodetic Survey Data: NOAA Vol. II, United States Department of Commerce, Coast and Geodetic Survey, Washington, DC, United States.

    Online Links:

    Hapke, Cheryl J., Himmelstoss, Emily A., Kratzmann, Meredith G., List, Jeffrey H., and Thieler, E. Robert, 2011, 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:

    Crowell, Mark, Leatherman, Stephen P., and Buckley, Michael K., 1991, Historical Shoreline Change: Error Analysis and Mapping Accuracy: Journal of Coastal Research Vol. 7, No. 3, Coastal Education and Research Foundation, Inc., Fort Lauderdale, FL, United States.

    Online Links:

    Heslin, Julia L., Henderson, Rachel E., and Himmelstoss, Emily A., 20211130, A GIS Compilation of Vector Shorelines for Puerto Rico from 2015 to 2018: data release DOI:10.5066/P9AZYW74, U.S. Geological Survey, Reston, VA.

    Online Links:

    Bracero-Marrero, Loderay, Barreto-Orta, Maritza, Hernández-Montcourt, Nias, Maldonado-González, Ruben, Himmelstoss, Emily A., and Heslin, Julia L., 20211130, A GIS compilation of Vector Shorelines and Shoreline Classification for Puerto Rico from 1970 and 2010: data release DOI:10.5066/P9SEUAHC, U.S. Geological Survey, Reston, VA.

    Online Links:

    Henderson, Rachel E., Heslin, Julia L., and Himmelstoss, Emily A., 20211130, Puerto Rico Shoreline Change: A GIS Compilation of Shorelines, Baselines, Intersects, and Change Rates using the Digital Shoreline Analysis System version 5.1: data release DOI:10.5066/P9FNRRN0, 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 are a compilation of shorelines from multiple sources spanning 86 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 the shorelines is varied and depends on the data source from which they were digitized.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This shoreline file is complete and contains historical shoreline segments used to calculate shoreline change rates along sections of the Puerto Rico coastline 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 taken into account in the uncertainty calculations referenced in the process steps.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None. Please see 'Distribution Info' for details.
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 (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Federal Center, Building 810, MS 302
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set?
  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?

Who wrote the metadata?

Dates:
Last modified: 17-Nov-2021
Metadata author:
Julia L. Heslin
U.S. Geological Survey
Geographer
384 Woods Hole Rd
Woods Hole, MA
USA

508-457-2230 (voice)
508-547-2310 (FAX)
jheslin@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9CLXCEG/PR_Historical_Shorelines_metadata.faq.html>
Generated by mp version 2.9.50 on Mon Nov 29 09:51:00 2021