Seafloor elevation change from 2002 to 2016 in the Upper Florida Keys

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Frequently anticipated questions:

What does this data set describe?

Title:
Seafloor elevation change from 2002 to 2016 in the Upper Florida Keys
Abstract:
The U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted research to quantify bathymetric changes in the Upper Florida Keys (UFK) from Triumph Reef to Pickles Reef within a 242.4 square-kilometer area. USGS staff calculated changes in seafloor elevation from 2002 to 2016 using light detection and ranging (lidar)-derived data acquired by the USGS in 2001 and 2002 and lidar-derived data acquired by the National Oceanic and Atmospheric Administration (NOAA) in 2016 and 2017. Most of the elevation data from these two time periods was collected during 2002 and 2016. As an abbreviated naming convention, we refer to this study time period and dataset as 2002-2016. An elevation change analysis between the 2002 and 2016 lidar data was performed to quantify and map impacts to seafloor elevation and to determine elevation and volume change statistics for 13 habitat types found in the UFK. This elevation change study was conducted under Florida Keys National Marine Sanctuary permit FKNMS-2016-068.
Supplemental_Information:
The 2002 lidar data were collected by the USGS using the National Aeronautics and Space Administration (NASA) Experimental Advanced Airborne Research Lidar (EAARL), a pulsed laser ranging system mounted onboard an aircraft to measure subaerial and submarine coastal topography. The 2016 lidar data were collected by the NOAA National Geodetic Survey (NGS) Remote Sensing Division using a Riegl VQ-820-G system. The lidar data are an ancillary product of NOAA's Coastal Mapping Program (CMP), created through a wider Integrated Ocean and Coastal Mapping initiative to increase support for multiple uses of the data.
  1. How might this data set be cited?
    Murphy, Kelly A., Yates, Kimberly K., and Zawada, David G., 20210121, Seafloor elevation change from 2002 to 2016 in the Upper Florida Keys: U.S. Geological Survey Data Release doi:10.5066/P9P42DUR, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    This is part of the following larger work.

    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, Munich, Germany.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -80.465007
    East_Bounding_Coordinate: -80.109513
    North_Bounding_Coordinate: 25.478116
    South_Bounding_Coordinate: 24.963888
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Jul-2001
    Ending_Date: 20-Feb-2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Multimedia presentation
  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):
      • Entity Point (60585610)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 17
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -81.0
      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 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in METERS
      The horizontal datum used is North American Datum of 1983 National Spatial Reference System (2007).
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988 (NAVD88) GEOID12B
      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?
    2002_2016_UFK_ElevationStatistics.csv
    Upper Florida Keys elevation change statistics per habitat type from 2002 to 2016. (Source: USGS)
    Habitat types in Upper Florida Keys study site
    The habitat types found in the Upper Florida Keys study site. Habitat types are defined by the Unified Florida Reef Tract Map Version 2.0 and based on the Unified Classification (UC) system Class Level 2. (Source: Florida Fish and Wildlife Conservation Commission (FWC))
    ValueDefinition
    Total Study SiteThe total Upper Florida Keys study site, includes 13 habitat types.
    Aggregate ReefAggregate reef larger than 1 hectare (ha), contiguous reef, lacking sand channels.
    Colonized PavementContiguous to patchy pavement, lacking spur and groove channel formation, presence of macroalgae, hard coral, gorgonians, and other sessile invertebrates, dense enough to obscure underlying rock.
    Individual or Aggregated Patch ReefPatch reefs smaller than 1 ha, isolated reefs often with distinct halo or reef features covering >10% of the area.
    Not ClassifiedAreas where habitat has not been classified.
    PavementContiguous to patchy pavement, lacking spur and groove channel formations.
    Pavement with Sand ChannelsAlternating linear sand and pavement formations, perpendicular to reef crest.
    Pavement with SeagrassContiguous to patchy pavement, lacking spur and groove channel formations with seagrass.
    Reef RubbleUnconsolidated, dead, unstable coral rubble.
    Scattered Coral Rock in Unconsolidated SedimentMostly sand, reef features covering <10% of the area.
    Seagrass ContinuousContinuous seagrass beds.
    Seagrass DiscontinuousDiscontinuous seagrass beds.
    Spur and GrooveAlternating linear sand and coral formations, perpendicular to reef crest.
    Unconsolidated SedimentUnconsolidated sediment.
    Total Points (no.)
    The total number of points within or on the boundary of each Upper Florida Keys habitat type. (Source: USGS)
    Range of values
    Minimum:75944
    Maximum:60585610
    Units:number of points
    Mean Historical Elevation (m)
    Mean elevation per habitat type in the Upper Florida Keys study site for 2002, in meters. (Source: USGS)
    Range of values
    Minimum:-9.75
    Maximum:-5.84
    Units:meters
    Mean Modern Elevation (m)
    Mean elevation per habitat type in the Upper Florida Keys study site for 2016, in meters. (Source: USGS)
    Range of values
    Minimum:-9.71
    Maximum:-5.89
    Units:meters
    Mean Elevation Change (m)
    Mean elevation change per habitat type in the Upper Florida Keys study site from 2002 to 2016, in meters. (Source: USGS)
    Range of values
    Minimum:-0.21
    Maximum:0.24
    Units:meters
    Mean Elevation Change SD (m)
    Standard deviation of the mean elevation change, in meters. (Source: USGS)
    Range of values
    Minimum:0.21
    Maximum:0.4
    Units:meters
    Elevation Loss Points (no.)
    The total number of erosion points within or on the boundary of each Upper Florida Keys habitat type. (Source: USGS)
    Range of values
    Minimum:16030
    Maximum:29981815
    Units:number of points
    Max Loss (m)
    Maximum erosion per habitat type in the Upper Florida Keys study site from 2002 to 2016, in meters. (Source: USGS)
    Range of values
    Minimum:-7.13
    Maximum:-1.44
    Units:meters
    Mean Loss (m)
    Mean erosion per habitat type in the Upper Florida Keys study site from 2002 to 2016, in meters. (Source: USGS)
    Range of values
    Minimum:-0.27
    Maximum:-0.11
    Units:meters
    Mean Loss SD (m)
    Standard deviation of the mean erosion, in meters. (Source: USGS)
    Range of values
    Minimum:0.11
    Maximum:0.19
    Units:meters
    Elevation Gain Points (no.)
    The total number of accretion points within or on the boundary of each Upper Florida Keys habitat type. (Source: USGS)
    Range of values
    Minimum:24259
    Maximum:30603795
    Units:number of points
    Max Gain (m)
    Maximum accretion per habitat type in the Upper Florida Keys study site from 2002 to 2016, in meters (Source: USGS)
    Range of values
    Minimum:1.14
    Maximum:15.13
    Units:meters
    Mean Gain (m)
    Mean accretion per habitat type in the Upper Florida Keys study site from 2002 to 2016, in meters. (Source: USGS)
    Range of values
    Minimum:0.15
    Maximum:0.36
    Units:meters
    Mean Gain SD (m)
    Standard deviation of the mean accretion, in meters. (Source: USGS)
    Range of values
    Minimum:0.16
    Maximum:0.36
    Units:meters
    2002_2016_UFK_VolumeStatistics.csv
    Volume statistics by habitat type in the Upper Florida Keys from 2002 to 2016. (Source: USGS)
    Habitat Types in the Upper Florida Keys Study Site
    The habitat types found in the Upper Florida Keys. Habitat types are defined by the Unified Florida Reef Tract Map Version 2.0 and based on the Unified Classification (UC) system Class Level 2. (Source: FWC)
    ValueDefinition
    Total Study SiteThe total Upper Florida Keys study site, includes 13 habitat types.
    Aggregate ReefAggregate reef larger than 1 hectare (ha), contiguous reef, lacking sand channels.
    Colonized PavementContiguous to patchy pavement, lacking spur and groove channel formation, presence of macroalgae, hard coral, gorgonians, and other sessile invertebrates, dense enough to obscure underlying rock.
    Individual or Aggregated Patch ReefPatch reefs smaller than 1 ha, isolated reefs often with distinct halo or reef features covering >10% of the area.
    Not ClassifiedAreas where habitat has not been classified.
    PavementContiguous to patchy pavement, lacking spur and groove channel formations.
    Pavement with Sand ChannelsAlternating linear sand and pavement formations, perpendicular to reef crest.
    Pavement with SeagrassContiguous to patchy pavement, lacking spur and groove channel formations with seagrass.
    Reef RubbleUnconsolidated, dead, unstable coral rubble.
    Scattered Coral Rock in Unconsolidated SedimentMostly sand, reef features covering <10% of the area.
    Seagrass ContinuousContinuous seagrass beds.
    Seagrass DiscontinuousDiscontinuous seagrass beds.
    Spur and GrooveAlternating linear sand and coral formations, perpendicular to the reef crest.
    Unconsolidated SedimentUnconsolidated sediment.
    Habitat Area (km^2)
    Habitat area, in kilometers squared. (Source: USGS)
    Range of values
    Minimum:0.3
    Maximum:242.12
    Units:km^2
    Gross Erosion Lower Limit (10^6m^3)
    Gross erosion minimum volume per habitat, in millions of cubic meters. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:3.77
    Units:10^6 m^3
    Gross Erosion Upper Limit (10^6m^3)
    Gross erosion maximum volume per habitat, in millions of cubic meters. (Source: USGS)
    Range of values
    Minimum:0.01
    Maximum:21.91
    Units:10^6 m^3
    Gross Accretion Lower Limit (10^6m^3)
    Gross accretion minimum volume per habitat, in millions of cubic meters. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:9.9
    Units:10^6 m^3
    Gross Accretion Upper Limit (10^6m^3)
    Gross accretion maximum value per habitat, in millions of cubic meters. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:30.05
    Units:10^6 m^3
    Net Volume Change Lower Limit (10^6m^3 Study Area^-1)
    Net volume change lower limit per habitat, in millions of cubic meters per study area. (Source: USGS)
    Range of values
    Minimum:-0.04
    Maximum:6.12
    Units:10^6 m^3 study area^-1
    Net Volume Change Upper Limit (10^6m^3 Study Area^-1)
    Net volume change upper limit per habitat, in millions of cubic meters per study area. (Source: USGS)
    Range of values
    Minimum:-2.01
    Maximum:8.14
    Units:10^6 m^3 study area^-1
    Area Normalized Volume Change Lower Limit (10^6m^3 km^-2)
    Area normalized volume change lower limit per habitat, in millions of cubic meters per kilometer squared. (Source: USGS)
    Range of values
    Minimum:-0.06
    Maximum:0.07
    Units:10^6 m^3 km^-2
    Area Normalized Volume Change Upper Limit (10^6m^3 km^-2)
    Area normalized volume change upper limit per habitat, in millions of cubic meters per kilometer squared. (Source: USGS)
    Range of values
    Minimum:-0.24
    Maximum:0.23
    Units:10^6 m^3 km^-2

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Kelly A. Murphy
    • Kimberly K. Yates
    • David G. Zawada
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Kimberly K. Yates
    Southeast Region: St. Petersburg Coastal and Marine Science Center
    Research Oceanographer
    600 4th Street South
    St. Petersburg, FL
    United States

    727-502-8059 (voice)
    kyates@usgs.gov

Why was the data set created?

These data were used to determine seafloor elevation and volume changes, from 2002 to 2016, in the Upper Florida Keys.

How was the data set created?

  1. From what previous works were the data drawn?
    2016 lidar (source 1 of 6)
    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Geodetic Survey (NGS), Remote Sensing Division, 20170614, 2016 NOAA NGS Topobathy Lidar DEM: Florida Keys Outer Reef Block 02: National Oceanic and Atmospheric Administration, Charleston, SC.

    Online Links:

    Other_Citation_Details: 2017a
    Type_of_Source_Media: topobathy data
    Source_Contribution:
    The original lidar data used to calculate elevation and volume change statistics in the Upper Florida Keys from 2002 to 2016.
    2016 lidar (source 2 of 6)
    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Geodetic Survey (NGS), Remote Sensing Division, 20170712, 2016 NOAA NGS Topobathy Lidar DEM: Florida Keys Outer Reef Block 03: National Oceanic and Atmospheric Administration, Charleston, SC.

    Online Links:

    Other_Citation_Details: 2017b
    Type_of_Source_Media: topobathy data
    Source_Contribution:
    The original lidar data used to calculate elevation and volume change statistics in the Upper Florida Keys from 2002 to 2016.
    2016 lidar (source 3 of 6)
    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Geodetic Survey (NGS), Remote Sensing Division, 20180219, 2017 NOAA NGS Topobathy Lidar DEM: Florida Keys Outer Reef Block 04: National Oceanic and Atmospheric Administration, Charleston, SC.

    Online Links:

    Type_of_Source_Media: topobathy data
    Source_Contribution:
    The original lidar data used to calculate elevation and volume change statistics in the Upper Florida Keys from 2002 to 2016.
    2002 lidar (source 4 of 6)
    John C. Brock, C. Wayne Wright, Matt Patterson, Amar Nayegandhi, Judd Patterson, Melanie S. Harris, and Lance Mosher, 2006, EAARL submarine topography—Biscayne National Park: United States Geological Survey, St. Petersburg, FL.

    Online Links:

    Type_of_Source_Media: bathymetric data
    Source_Contribution:
    The original lidar data used to calculate elevation and volume change statistics in the Upper Florida Keys from 2002 to 2016.
    2002 lidar (source 5 of 6)
    John C. Brock, C. Wayne Wright, Amar Nayegandhi, Matt Patterson, Iris Wilson, and Laurinda J. Travers, 200712, EAARL Submarine Topography - Northern Florida Keys Reef Tract: United States Geological Survey, St. Petersburg, FL.

    Online Links:

    Type_of_Source_Media: bathymetric data
    Source_Contribution:
    The original lidar data used to calculate elevation and volume change statistics in the Upper Florida Keys from 2002 to 2016.
    Habitat file (source 6 of 6)
    Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 20170113, Unified Florida Reef Tract Map Version 2.0: Fish and Wildlife Research Institute, St. Petersburg, FL.

    Online Links:

    Type_of_Source_Media: Vector digital data
    Source_Contribution:
    This shapefile was used to divide the DEM by habitat types using Unified Classification (UC) Class Level 2.
  2. How were the data generated, processed, and modified?
    Date: 2020 (process 1 of 15)
    Step 1: The original 2002 Experimental Advanced Airborne Research Lidar (EAARL) Submarine Topography: Biscayne National Park and EAARL Submarine Topography: Northern Florida Keys Reef Tract digital elevation models (DEMs) were downloaded from two U.S. Geological Survey (USGS) Open-File Reports (Brock and others, 2006 and Brock and others, 2007). Horizontal coordinates were provided in the North American Horizontal Datum of 1983 (NAD83) Universal Transverse Mercator (UTM) Zone 17 North, GRS80 ellipsoid; and vertical positions were referenced to the North American Vertical Datum of 1988 (NAVD88), in meters (m). Global Mapper version 19.1 was used to export the two DEMs as a single, merged lidar DEM in the geographic tagged image file format (GEOTIFF). Using VDatum version 3.9, a publicly available software from the National Oceanic and Atmospheric Administration (NOAA) (https://vdatum.noaa.gov/, accessed on September 7, 2018), the merged 2002 lidar DEM was transformed from NAD83 to NAD83 National Spatial Reference System of 2007 (NSRS2007) National Readjustment horizontal datum, and from GEOID03 to the GEOID12B geoid model.
    Date: 2020 (process 2 of 15)
    Step 2: The original 2016 DEMs were acquired from NOAA’s Data Access Viewer (https://coast.noaa.gov/dataviewer/#/lidar/search/) using the “Custom Download” capability of NOAA’s Digital Coast website. The elevation search option was used to download three topobathymetric datasets: 2016 NOAA NGS Topobathy Lidar: Florida Keys Outer Reef Blocks 02, 03, and 2017 NOAA NGS Topobathy Lidar: Florida Keys Outer Reef Block 04 (National Oceanic and Atmospheric Administration, 2017a, b; and National Oceanic and Atmospheric Administration, 2018). The data were downloaded with the following parameters: “Projection”: UTM; “Zone”: Zone 17 Range 084W-078W; “Horizontal Datum”: NAD83; “Horizontal Units”: Meters; “Vertical Datum”: NAVD88; “Vertical Units”: Meters; “File Format”: TIFF 32-bit Float; “Bin Method”: TIN; “Bin Size”: 1.0; “Bin Units”: Meters; “Data Classification”: Bathymetric Lidar Points; “Data Returns”: Any Points; “Ancillary Data”: No Ancillary Data; and “Geoid Name”: GEOID12B. Using Global Mapper, the three DEMs were merged into a single DEM and transformed into the NAD83 (NSRS2007) National Readjustment horizontal datum.
    Date: 2020 (process 3 of 15)
    Step 3: The 2016 DEM contained a small region of sub-aerial elevations that were manually removed in Global Mapper. Polygons encompassing the sub-aerial regions were created using the “Digitizer” tool and the “Create New Feature Area” function. The polygons were selected, and the “Cut Out Currently Selected Polygon(s)” parameter was enabled within the “Cropping” tab of the 2016 DEM “Elevation Options” window to remove the section of the 2016 DEM that intersects with the polygons encompassing the sub-aerial elevations.
    Date: 2020 (process 4 of 15)
    Step 4: Using Esri ArcGIS Desktop Advanced version 10.6 (ArcMap), footprints of the original 2002 and 2016 DEMs were created with the “Reclassify (Spatial Analyst)” tool. To create each raster file, all old data values were replaced with the number 1 and “No Data” values were left as “No Data”. The “Raster to Polygon (Conversion)” tool was then used to create a footprint of each original DEM by converting the raster files to polygon shapefiles, creating the 2002_UFK_Footprint and 2016_UFK_Footprint shapefiles.
    Date: 2020 (process 5 of 15)
    Step 5: A polygon shapefile of the geometric intersection between the two DEMs was created with the “Intersect (Analysis)” tool by adding the 2002_UFK_Footprint and 2016_UFK_Footprint shapefiles as “Input features”, creating the Intersect_Footprint shapefile. Then, the 2002 and 2016 DEMs were clipped to the extent of the Intersect_Footprint shapefile using the “Clip (Data Management)” tool by specifying one of the DEMs as the “Input Raster”, the Intersect_Footprint shapefile as the “Output Extent”, and box checked for “Use Input Features for Clipping Geometry”, creating the 2002_UFK_LidarClip and 2016_UFK_LidarClip GEOTIFFs.
    Date: 2020 (process 6 of 15)
    Step 6: A 2-m grid was generated in Global Mapper using the “Digitizer” tool. To define the correct geographic location and extent of the 2-m grid, the Intersect_Footprint shapefile was opened. When the Intersect_Footprint shapefile was opened, it automatically displayed in the NAD83 horizontal datum, despite being set to the NAD83 (NSRS2007) National Readjustment horizontal datum. Using the “Configure” tool, the correct horizontal datum was specified. The “Digitizer” tool was used to select the Intersect_Footprint shapefile, and within the “Advanced Feature Creation Options” window, “Create Regular Grid of User Specified Size/Orientation” was selected to create a 2-m spaced grid with the following parameters: “Grid Cell Width”: 2; “Grid Cell Height”: 2; “Calculate Grid Cell Counts to Fill Rectangle”: enabled; “Crop Generated Grid to Selected Area Feature”: enabled; “Keep Area if Any Part in Crop Area”: enabled; “Create Points at Grid Cell Centers”: enabled; and “Crop to Selected Area Feature(s)”: enabled. The remaining default parameters were left the same, and the tool was run, creating the 2-m grid at the extent of the Intersect_Footprint shapefile.
    Date: 2020 (process 7 of 15)
    Step 7: The 2-m grid was shifted to center the grid points on the DEM pixels. The 2-m grid was selected using the “Digitizer” tool in Global Mapper, and in the “Move/Reshape Feature(s)” window, the “Shift (Offset) Selected Feature(s)” tab was selected to open the “Specify Offset to Apply to Point(s)” menu and the following parameters were set: “Units”: meters; “X/Longitude Offset”: +0.5; and “Y/Latitude Offset”: +0.5.
    Date: 2020 (process 8 of 15)
    Step 8: Grid points that were shifted into no-data areas were removed to avoid the extraction of no-data values. The Intersect_Footprint shapefile was selected using the “Digitizer” tool, and the 2-m grid was left unselected. The 2-m grid “Options” menu was opened by right clicking the 2-m grid layer in the “Control Center”, and “Export Layers to New File(s)” was selected from the “Layer” window. Within the “Select Export Format” menu, “Data Format” was set to Shapefile. The “Export Bounds” tab was selected, and the “Crop to Selected Area Features” parameter was enabled in the “Shapefile Export Options” window. By exporting the 2-m grid with this parameter enabled, grid points that were in no-data areas were removed, creating the 2m_grid shapefile. Before the next steps, the 2m_grid shapefile was reimported into Global Mapper.
    Date: 2020 (process 9 of 15)
    Step 9: Horizontal coordinates (x,y) were added by selecting the 2m_grid shapefile with the “Digitizer” tool and “Add Coordinates/Bounds Attributes to Selected Features” was selected from the “Attribute/Style Functions” window. Horizontal coordinates were added to each grid point based on the projection of the data frame.
    Date: 2020 (process 10 of 15)
    Step 10: Elevation values were extracted from the 2002 and 2016 DEMs at the location of the 2m_grid shapefile. The 2002 DEM was opened in Global Mapper and the resampling method was changed by opening the “Options” menu of the DEM and “Resampling” was set to No Resampling (Nearest Neighbor). The DEM and 2m_grid shapefile were selected using the “Digitizer” tool. Within the “Attributes/Style Functions” window, “Apply Elevations to Selected Feature(s)” was selected, with “Terrain Layers” as the only selected parameter. An attribute named ELEVATION was created containing the elevation values extracted from the 2002 DEM. Using the “Digitizer” tool, the “Edit Selected Features” window was selected to rename the ELEVATION attribute to ELEV2002. The same steps were repeated to extract elevation values from the 2016 DEM at the location of the 2m_grid shapefile and to rename the ELEVATION attribute containing the 2016 extracted elevation values to ELEV2016.
    Date: 2020 (process 11 of 15)
    Step 11: The elevation-difference between the 2002 and 2016 extracted elevation values was calculated using the “Digitizer” tool. The 2m_grid shapefile was selected and “Calculate/Copy Attributes for Feature Selection” was selected from the “Attribute/Style Functions” window. The elevation-difference was calculated using the following parameters: “Select Existing or Create New Attribute to Assign Calculated Values”: Diff_m; “Source Attribute”: ELEV2016; “Operation”: Subtract; and “Use Attribute Value”: ELEV2002. ELEV2016 represents the modern elevation values and ELEV2002 represents the historical elevation values. The final 2-m grid was exported using the “Export Layers to New File(s)” function with “Data Format” set to Shapefile, creating the 2002_2016_UFK_ElevationChange_Points shapefile.
    Date: 2020 (process 12 of 15)
    Step 12: The original Unified Florida Reef Tract Map version 2.0 shapefile was downloaded from http://ocean.floridamarine.org/IntegratedReefMap/UnifiedReefTract.htm. Using ArcMap, the original habitat shapefile was modified using the “Clip (Analysis)” tool to clip the habitat shapefile to the extent of the 2002 and 2016 DEMs by specifying the habitat shapefile as the “Input Features” and the Intersect_Footprint shapefile as the “Clip Features”, creating the 2002_2016_UFK_HabitatClip shapefile. Using the “Select by Attribute” tool, 13 individual habitat shapefiles were created from 2002_2016_UFK_HabitatClip shapefile by selecting one ClassLv2 habitat and exporting as a separate shapefile.
    Date: 2020 (process 13 of 15)
    Steps 13: Elevation change statistics were determined by habitat type using the elevation-difference points from the 2002_2016_UFK_ElevationChange_Points shapefile in ArcGIS Pro version 2.1.3. The “Select Layer by Location (Data Management)” tool was used to extract points within or on the boundary of a specific habitat type by using the following parameters: “Input Feature Layer”: 2002_2016_UFK_ElevationChange_Points; “Relationship”: INTERSECT; “Selecting Features”: Habitat shapefile; “Search Distance”: left blank; and “Selection Type”: NEW_SELECTION. An ArcGIS Pro model was created to automate the process, since these steps had to be repeated for 13 habitat types. Elevation change statistics were compiled by habitat type into a comma separated values (CSV) file using Microsoft Excel 2016, see 2002_2016_UFK_ElevationStatistics.csv.
    Date: 2020 (process 14 of 15)
    Step 14: An elevation change surface model was created in ArcMap using the calculated elevation-difference (Diff_m) points from the 2002_2016_UFK_ElevationChange_Points shapefile. Due to the memory limitation ArcMap encounters when attempting to edit large Triangulated Irregular Networks (TINs), a Python script was developed to create and edit a TIN following the Yates and others (2017) TIN creation method. Using the Python script, a TIN was created from the Diff_m points using the “Create Tin (3D Analyst)” tool by specifying the 2002_2016_UFK_ElevationChange_Points shapefile as the “Input Feature Class”, Diff_m as the “Height Field” and Mass_Points as the “Type”, creating the 2002_2016_UFK_ElevationChange_TIN file. The 2002_2016_UFK_ElevationChange_TIN file was then delineated using the “Delineate TIN Data Area (3D Analyst)” tool by specifying the 2002_2016_UFK_ElevationChange_TIN file as the “Input TIN”, a “Maximum Edge Length” of 2.828428 (hypotenuse of a triangle with 2-m legs) and the “Method” set to ALL. The delineated 2002_2016_UFK_ElevationChange_TIN file was clipped to the extent of the 2002 and 2016 DEMs using the “Edit TIN (3D Analyst)” tool with the following parameters: “Input TIN”: 2002_2016_UFK_ElevationChange_TIN file; “Input Features Class”: Intersect_Footprint shapefile; “Height Field”: None; “Tag Field”: None; and “Type”: Hard clip. Due to the large file size of the final 2002_2016_UFK_ElevationChange_TIN file, ArcMap couldn’t render or run geoprocessing tools on the TIN, and therefore, ArcGIS Pro was used for subsequent processing steps.
    Date: 2020 (process 15 of 15)
    Step 15: Volume change statistics per habitat type were calculated using the final 2002_2016_UFK_ElevationChange_TIN file in ArcGIS Pro. Surface volume changes were calculated for four cases using the “Surface Volume (3D Analyst)” tool. To calculate the net erosion lower limit (case 1) the “Reference Plane” was set to BELOW and the “Plane Height” set to -0.24 m. For the net erosion upper limit (case 2) the “Reference Plane” was set to BELOW and the “Plane Height” set to 0 m. For the net accretion lower limit (case 3) the “Reference Plane” was set to ABOVE and the “Plane Height” was set to 0.24 m. For the net accretion upper limit (case 4) the “Reference Plane” was set to ABOVE and the “Plane Height” was set to 0 m. A 0.24 m threshold was determined by vertical error analysis using the uncertainties reported in the metadata of the original 2002 (0.20 m) and 2016 (0.15 m) DEMs to calculate the Root Mean Square Error (RMSE) of 0.24 m. Minimum net volume change was calculated by summing results from cases 1 and 3. Maximum net volume change was calculated by summing results from cases 2 and 4. Area normalized volume change lower limit was calculated by dividing the minimum net volume change for each habitat by the habitat's total area. The area normalized volume change upper limit was calculated by dividing the maximum net volume for each habitat by the habitat's total area. An ArcGIS Pro model was created to automate the process, since these steps had to be repeated for 13 habitat types. Volume change statistics were compiled by habitat type in CSV format using Excel, see 2002_2016_UFK_VolumeStatistics.csv.
  3. What similar or related data should the user be aware of?

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

  1. How well have the observations been checked?
    Datasets were visually compared by USGS staff in Esri ArcGIS Desktop Advanced version 10.6 for identification of anomalous elevations or data inconsistencies.
  2. How accurate are the geographic locations?
    For the 2016 lidar, the data positions were obtained using post-processed kinematic global positioning system (KGPS) methods. The horizontal accuracy of the 2002 and 2016 data is better than plus or minus 1.0 meter (m); Quantitative Value: 1.0 m.
  3. How accurate are the heights or depths?
    For the 2016 lidar, the data positions were obtained using post-processed KGPS methods. Data used to validate the lidar were collected with static GPS observational equipment and compared against the published data. The vertical accuracy of the 2002 data is better than plus or minus 0.20 m; Quantitative Value: 0.20 m. The vertical accuracy of the 2016 data is better than plus or minus 0.15 m; Quantitative Value: 0.15 m.
  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 and Yates and others (2017) carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Data cover the area specified for this project, without any 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: none
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Kimberly K. Yates
    Southeast Region: St. Petersburg Coastal and Marine Science Center
    Research Oceanographer
    600 4th Street South
    St. Petersburg, FL
    United States

    727-502-8059 (voice)
    kyates@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described or contained herein. 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: 17-Dec-2020
Metadata author:
Kimberly K. Yates
Southeast Region: St. Petersburg Coastal and Marine Science Center
Research Oceanographer
600 4th Street South
St. Petersburg, FL
United States

727-502-8059 (voice)
kyates@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/2002_2016_UFK_metadata.faq.html>
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