Seafloor Elevation and Volume Change along the Upper Florida Keys reef tract: 1934 to 2002 and 2002 to 2016

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Frequently anticipated questions:

What does this data set describe?

Title:
Seafloor Elevation and Volume Change along the Upper Florida Keys reef tract: 1934 to 2002 and 2002 to 2016
Abstract:
Coral reefs serve as natural barriers that protect adjacent shorelines from coastal hazards such as storms, waves, and erosion. The U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted research to quantify the combined effect of all constructive and destructive processes on modern coral reef ecosystems by measuring regional-scale changes in seafloor elevation. USGS staff conducted research to quantify bathymetric changes in the Northern Florida Keys from Triumph Reef to Pickles Reef during two time periods, 1934 to 2002, and 2002 to 2016, within a 234.2 square-kilometer area. USGS staff calculated changes in seafloor elevation for both time periods using historical hydrographic surveys (H-sheets) collected by the U.S. Coast and Geodetic Survey (USC&GS) in 1934 and 1935, light detection and ranging (lidar)-derived digital elevation models (DEMs) acquired by the USGS in 2001 and 2002, and lidar-derived DEMs acquired by the National Oceanic and Atmospheric Administration (NOAA) in 2016 and 2017. An elevation change analysis for the two time periods was performed to quantify and map impacts to seafloor elevation for the full study site and 3 sub-regions: Upper, Middle, and Lower. Elevation and volume change statistics were also computed for eleven habitat types found within the study area. For more information about the methods used in this study, refer to Yates and others (2017) and Johnson and others (2026).
Supplemental_Information:
All data sources and descriptions used in the creation of ElevationChange_1934-2002.csv and ElevationChange_2002-2016.csv are listed in Yates and others (2017) and Johnson and others (2026), respectively. For both time periods, each sub-region CSV file (Upper, Middle, and Lower) is a duplicate of the complete study site CSV file (ElevationChange_1934-2002.csv or ElevationChange_2002-2016.csv) but clipped to the extent of the defined sub-region, and therefore, the same attributes are used.
  1. How might this data set be cited?
    Johnson, Selena A., Zawada, David G., and Yates, Kimberly K., 20260202, Seafloor Elevation and Volume Change along the Upper Florida Keys reef tract: 1934 to 2002 and 2002 to 2016:.

    This is part of the following larger work.

    Johnson, Selena A., Zawada, David G., and Yates, Kimberly K., 20260202, Seafloor Elevation and Volume Change along the Upper Florida Keys Reef Tract: 1934 to 2002 and 2002 to 2016: U.S. Geological Survey data release doi:10.5066/P1VGATCF, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -80.46500169
    East_Bounding_Coordinate: -80.10980672
    North_Bounding_Coordinate: 25.47811131
    South_Bounding_Coordinate: 24.96580389
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1934
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tabular digital data, 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 Point data set. It contains the following vector data types (SDTS terminology):
      • Point (25926)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 17N
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -81
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1
      Ordinates (y-coordinates) are specified to the nearest 1
      Planar coordinates are specified in Meters
      The horizontal datum used is North American Datum of 1983 (1986).
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988 (NAVD88) GEOID03
      Altitude_Resolution: 0.2
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    ElevationChange_1934-2002.csv
    Comma separated values (.csv) file, containing the elevation point locations and associated seafloor elevation change values for the full study area from 1934 to 2002. Additional data files were derived from this dataset, defined by the three sub-regions (lower, middle upper), also provided in .csv format. The range of values reported below are for the entire study area data file. (Source: USGS)
    HSHEET
    Hydrographic survey sheet number. The hydrographic sheet (h-sheet) from which the historical bathymetric elevation data was collected. (Source: NOAA USC&GS (https://www.ngdc.noaa.gov/hydro-survey-search/#!/)) H05536, H05578, H05726A, H05878A, H05879A
    YEAR
    Year the hydrographic sheet was published. (Source: NOAA USC&GS)
    Range of values
    Minimum:1934
    Maximum:1935
    Longitude (UTM, meters)
    NAD83(1986), UTM zone 17N geographic coordinate of sample point, in meters. (Source: USGS)
    Range of values
    Minimum:554001.2320
    Maximum:589481.9666
    Units:Meters
    Latitude (UTM, meters)
    NAD83(1986), UTM zone 17N geographic coordinate of sample point, in meters. (Source: USGS)
    Range of values
    Minimum:2761453.4630
    Maximum:2817998.9500
    Units:Meters
    Historical sounding (NAVD88 (GEOID03), meters)
    Historical sounding. Historical depth in NAVD88 using the GEOID03 geoid model. Negative values indicate positions below local mean sea level. (Source: U.S. Coast and Geodetic Survey)
    Range of values
    Minimum:-19.0321
    Maximum:-0.9554
    Units:Meters
    LiDAR elevation (NAVD88 (GEOID03), meters)
    Modern depth in NAVD88. Negative values indicate below local mean sea level. (Source: USGS)
    Range of values
    Minimum:-16.67037964
    Maximum:-0.972164929
    Units:Meters
    Difference = LiDAR - Historical (meters)
    The difference between the modern (lidar) and historical (H-sheets) depths. Negative values indicate loss of seafloor elevation. Positive values indicate a gain in seafloor elevation. (Source: USGS)
    Range of values
    Minimum:-8.254686717
    Maximum:6.464020674
    Units:Meters
    ElevationChange_2002-2016.csv
    Comma separated values (.csv) file, containing the elevation point locations and associated seafloor elevation change values for the full study area from 2002 to 2016. Additional data files were derived from this dataset, defined by the three sub-regions (lower, middle upper), also provided in .csv format. The range of values reported below are for the entire study area data file. (Source: USGS)
    Longitude (UTM, meters)
    NAD83 (1986), UTM zone 17N geographic coordinate of sample point, in meters. (Source: USGS)
    Range of values
    Minimum:554001.2320
    Maximum:589481.9666
    Units:Meters
    Latitude (UTM, meters)
    NAD83 (1986), UTM zone 17N geographic coordinate of sample point, in meters. (Source: USGS)
    Range of values
    Minimum:2761453.4630
    Maximum:2817998.9500
    Units:Meters
    2002 LiDAR elevation (NAVD88 (GEOID03), meters)
    2002 LiDAR depth in NAVD88. Negative values indicate below local mean sea level. (Source: USGS)
    Range of values
    Minimum:-16.67037964
    Maximum:-0.972164929
    Units:Meters
    2016 LiDAR elevation (NAVD88,GEOID03, meters)
    2016 LiDAR depth in NAVD88. Negative values indicate below local mean sea level. (Source: USGS)
    Range of values
    Minimum:-16.64999962
    Maximum:-0.959999979
    Units:Meters
    Difference = 2016_LiDAR - 2002_LiDAR (meters)
    The difference between the modern (2016 lidar) and historical (2002 lidar) depths. Negative values indicate loss of seafloor elevation. Positive values indicate a gain in seafloor elevation. (Source: USGS)
    Range of values
    Minimum:-2.22014606
    Maximum:8.93669844
    Units:Meters
    Entity_and_Attribute_Overview:
    LowerRegion.shp, MiddleRegion.shp, UpperRegion.shp: Boundary shapefiles were created by hand, that define the three sub-regional boundaries of the study area. These shapefiles are included in the file Subregion_boundary_definitions.zip.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.
    Entity_and_Attribute_Overview:
    Footprint_2016_NOAA_blocks2-4_clip_2002_EAARL_n83_1986_n88_g03_no_subaerial.shp: Footprint shapefile of the geometric intersection area between the 2002 and 2016 DEMs, used to produce the elevation change datasets. This shapefile is included in the file LidarOverlappingArea_2002-2016.zip.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.
    Entity_and_Attribute_Overview:
    UnifiedFloridaReefTract_n83_1986_g03_clip_2002_2016Lidars_clip_TIN.shp: Shapefile of the habitat map clipped to the intersecting area of the 2002 and 2016 DEMs, used to produce the elevation change datasets. This shapefile is included in the file HabitatMap_NAD83-1986.zip.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Selena A. Johnson
    • David G. Zawada
    • Kimberly K. Yates
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Selena A. Johnson
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
    Research Physical Scientist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8053 (voice)
    selenajohnson@usgs.gov

Why was the data set created?

These data were used to provide a comprehensive assessment of the combined effect of all processes influencing seafloor accretion and erosion by measuring changes in seafloor elevation and volume for a coral reef ecosystem in the Florida Keys over the last several decades. This study is a follow-on study to previous work published in Yates and others (2017) and follows the same data processing steps as detailed in that publication.

How was the data set created?

  1. From what previous works were the data drawn?
    H05536, H05578, H05726A, H05878A, and H05879A (source 1 of 5)
    National Oceanic and Atmospheric Administration (NOAA) U.S. Coast and Geodetic Survey (USC&GS), 1935, Historical hydrographic sheets: NOAA Office of Coast Survey, Online.

    Online Links:

    Type_of_Source_Media: H-sheets
    Source_Contribution:
    Hydrographic sheets (h-sheets) collected in 1934 and 1935 used to calculate changes in seafloor elevation in the Northern Florida Keys study area. More information is available in Yates and others (2017) and Johnson and others (2026) about the methods used to derive seafloor elevation change using this data source.
    2001 and 2002 lidar-derived DEMs (source 2 of 5)
    Brock, John C., Wright, Wayne C., Nayegandhi, Amar, Patterson, Matt, Travers, Laurinda J., and Wilson, Iris, 2007, EAARL submarine topography - Northern Florida Keys Reef Tract: U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: DEM
    Source_Contribution:
    Lidar-derived DEMs collected in 2001 and 2002 used to calculate changes in seafloor elevation in the Northern Florida Keys study area. More information is available in Yates and others (2017) and Johnson and others (2026) about the methods used to derive seafloor elevation change using this data source.
    2001 and 2002 lidar-derived DEMs (source 3 of 5)
    Brock, John C., Wright, Wayne C., Nayegandhi, Amar, Patterson, Judd, Harris, Melanie S., and Mosher, Lance, 2006, EAARL submarine topography—Biscayne National Park: U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: DEM
    Source_Contribution:
    Lidar-derived DEMs collected in 2001 and 2002 used to calculate changes in seafloor elevation in the Northern Florida Keys study area. More information is available in Yates and others (2017) and Johnson and others (2026) about the methods used to derive seafloor elevation change using this data source.
    2016 lidar-derived DEM (source 4 of 5)
    National Oceanic and Atmospheric Administration (NOAA), 2017, 2016 NOAA NGS Topobathy Lidar: Florida Keys Outer Reef Blocks 02 & 03: NOAA Office for Coastal Management, Charleston, SC.

    Online Links:

    Type_of_Source_Media: DEM
    Source_Contribution:
    Lidar-derived DEM collected in 2016 used to calculate changes in seafloor elevation in the Northern Florida Keys study area. More information is available in Yates and others (2017) and Johnson and others (2026) about the methods used to derive seafloor elevation change using this data source.
    2017 lidar-derived DEM (source 5 of 5)
    National Oceanic and Atmospheric Administration (NOAA), 2017, 2017 NOAA NGS Topobathy Lidar: Florida Keys Outer Reef, Block 04: NOAA Office for Coastal Management, Charleston, SC.

    Online Links:

    Type_of_Source_Media: DEM
    Source_Contribution:
    Lidar-derived DEM collected in 2017 used to calculate changes in seafloor elevation in the Northern Florida Keys study area. More information is available in Yates and others (2017) and Johnson and others (2026) about the methods used to derive seafloor elevation change using this data source.
  2. How were the data generated, processed, and modified?
    Date: 2020 (process 1 of 3)
    To allow direct comparison between the time periods of 1934 to 2002 and 2002 to 2016, the geometric intersection between the 2002 and 2016 DEMs was defined. Using ArcMap version 10.7, footprints of the 2002 and 2016 merged DEMs were created using the "Reclassify (Spatial Analyst)" geoprocessing tool. To create each raster file, all old data values were replaced with 1 and 'No Data' values were left as 'No Data'. Then, the output raster was converted into a polygon shapefile (.shp) using the "Raster to Polygon (Conversion)" geoprocessing tool. A polygon shapefile of the geometric intersection between the 2002 and 2016 merged DEMs was created with the "Intersect (Analysis)" geoprocessing tool by adding the two DEM footprint shapefiles as 'Input features', creating Footprint_2016_NOAA_blocks2-4_clip_2002_EAARL_n83_1986_n88_g03_no_subaerial.shp file. The Footprint_2016_NOAA_blocks2-4_clip_2002_EAARL_n83_1986_n88_g03_no_subaerial.shp file was used to clip each dataset (h-sheets and lidar) prior to elevation and volume change analyses. Additional details are provided in Johnson and others (2026). This shapefile is provided in LidarOverlappingArea_2002-2016.zip. Data sources used in this process:
    • H05536, H05578, H05726A, H05878A, and H05879A
    • 2001 and 2002 lidar-derived DEMs
    • 2016 and 2017 lidar-derived DEMs
    Data sources produced in this process:
    • Footprint_2016_NOAA_blocks2-4_clip_2002_EAARL_n83_1986_n88_g03_no_subaerial.shp
    Date: 2020 (process 2 of 3)
    Methods from Yates and others (2017) were used for the 1934-2002 Upper Florida Keys analysis for the smaller area in the Upper Florida Keys region used in this study. Yates and others (2017) also identified sub-regional patterns in elevation change for the 1934-2002 period. Shapefiles were created that define these sub-regional boundaries by hand for use in this study (UpperRegion.shp, MiddleRegion.shp, LowerRegion.shp). These shapefiles are included in the file Subregion_boundary_definitions.zip. Data sources produced in this process:
    • ElevationChange_1934-2002.csv
    • UpperRegion.shp
    • MiddleRegion.shp
    • LowerRegion.shp
    • ElevationChange_1934-2002_LowerRegion.csv
    • ElevationChange_1934-2002_MiddleRegion.csv
    • ElevationChange_1934-2002_UpperRegion.csv
    Date: 2020 (process 3 of 3)
    The methods outlined in Johnson and others (2026) were performed for the 2002-2016 Northern Florida Keys and sub-regional elevation and volume change datasets in this release. Data sources produced in this process:
    • ElevationChange_2002-2016.csv
    • UpperRegion.shp
    • MiddleRegion.shp
    • LowerRegion.shp
    • ElevationChange_2002-2016_LowerRegion.csv
    • ElevationChange_2002-2016_MiddleRegion.csv
    • ElevationChange_2002-2016_UpperRegion.csv
  3. What similar or related data should the user be aware of?
    Yates, Kimberly K., Zawada, David G., Smiley, Nathan A., and Tiling-Range, Ginger, 20170420, Divergence of seafloor elevation and sea level rise in coral reef ecosystems: Biogeosciences Volume 12, Issue 6, European Geosciences Union, Munich, Germany.

    Online Links:

    Johnson, Selena, A., Zawada, David G., Yates, Kimberly K., and Jenkins, Connor, M., 20260201, Long- versus short-term changes in seafloor elevation and volume of the Upper Florida Keys reef tract: 1935–2002 and 2002–2016: Remote Sensing Volume 18, Issue 3, MDPI, Basel, Switzerland.

    Online Links:

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

  1. How well have the observations been checked?
    A detailed accuracy assessment and error analysis are presented in Johnson and others (2026).
  2. How accurate are the geographic locations?
    Raw elevation measurements have been determined to be within 1-meter (m) horizontal accuracy. Horizontal point locations were projected to the North American Datum of 1983 (NAD83 [1986]), Universal Transverse Mercator (UTM) Zone 17 North (17N) coordinate system.
  3. How accurate are the heights or depths?
    Elevations of the 2002 DEM are vertically consistent with the point elevation data, +/-20 centimeters (cm). Elevations of the 2016 DEM are vertically consistent with the point elevation data, +/-15 cm. Vertical point locations were projected to the North American Vertical Datum of 1988 (NAVD88) coordinate system using the GEOID03 geoid model.
  4. Where are the gaps in the data? What is missing?
    This dataset is considered complete for the information presented, as described in the abstract section. Users are advised to read the rest of the metadata record for additional details pertaining to slightly different data processing steps used for the 2002-2016 elevation change data.
  5. How consistent are the relationships among the observations, including topology?
    Data cover area specified for this project without known issues.

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.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    Attn: USGS SPCMSC Data Management
    600 4th Street South
    Saint Petersburg, FL
    United States

    727-502-8000 (voice)
    gs-g-spcmsc_data_inquiries@usgs.gov
  2. What's the catalog number I need to order this data set? ElevationChange_1934-2002.csv, ElevationChange_1934-2002_LowerRegion.csv, ElevationChange_1934-2002_MiddleRegion.csv, ElevationChange_1934-2002_UpperRegion.csv, ElevationChange_2002-2016.csv, ElevationChange_2002-2016_LowerRegion.csv, ElevationChange_2002-2016_MiddleRegion.csv, ElevationChange_2002-2016_UpperRegion.csv, LowerRegion.shp, MiddleRegion.shp, UpperRegion.shp, Footprint_2016_NOAA_blocks2-4_clip_2002_EAARL_n83_1986_n88_g03_no_subaerial.shp, UnifiedFloridaReefTract_n83_1986_g03_clip_2002_2016Lidars_clip_TIN.shp
  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. Any use of trade, firm, or product 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: 02-Feb-2026
Metadata author:
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
Attn: USGS SPCMSC Data Management
600 4th Street South
Saint Petersburg, FL
United States

727-502-8000 (voice)
gs-g-spcmsc_data_inquiries@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/ElevationChange_1934_2002_2016_Metadata.faq.html>
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