Crocker Reef, Florida, 2016-2017 Seafloor Elevation Stability Models, Maps, and Tables

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Frequently anticipated questions:

What does this data set describe?

Title:
Crocker Reef, Florida, 2016-2017 Seafloor Elevation Stability Models, Maps, and Tables
Abstract:
The U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted research to identify areas of seafloor elevation stability and instability based on elevation changes between the years of 2016 and 2017 at Crocker Reef near Islamorada, Florida (FL), within a 33.62 square-kilometer area. USGS SPCMSC staff used seafloor elevation-change data from Yates and others (2019) derived from an elevation-change analysis between two elevation datasets acquired in 2016 and 2017 using the methods of Yates and others (2017). A seafloor stability threshold was determined for the 2016-2017 Crocker Reef elevation-change dataset based on the vertical uncertainty of the 2016 and 2017 digital elevation models (DEMs). Five stability categories (which include, Stable: 0.0 meters (m) to ±0.24 m or 0.0 m to ±0.49 m; Moderately stable: ±0.25 m to ±0.49 m; Moderately unstable: ±0.50 m to ±0.74 m; Mostly unstable: ±0.75 m to ±0.99 m; and Unstable: ±1.00 m to Max/Min elevation change) were created and used to define levels of stability and instability for each elevation-change value (8,402,223 data points at 2-m horizontal resolution) based on the amount of erosion and accretion during the 2016 to 2017 time period. Seafloor-stability point and triangulated irregular network (TIN) surface models were created at five different elevation-change data resolutions (1st order through 5th order) with each resolution becoming increasingly more detailed. The stability point models were used to determine the level of seafloor stability at nine habitat types found at Crocker Reef. This data release includes ArcGIS map packages containing the binned and color-coded stability point and surface (TIN) models and habitat files; maps of each stability model; and data tables containing stability and elevation-change data for the habitat types. Data were collected under Florida Keys National Marine Sanctuary permit FKNMS-2016-068.
  1. How might this data set be cited?
    Murphy, Kelly A., and Yates, Kimberly K., 20210628, Crocker Reef, Florida, 2016-2017 Seafloor Elevation Stability Models, Maps, and Tables:.

    This is part of the following larger work.

    Murphy, Kelly A., and Yates, Kimberly K., 20210628, Crocker Reef, Florida, 2016-2017 Seafloor Elevation Stability Models, Maps, and Tables: U.S. Geological Survey data release doi:10.5066/P9HWFXHE, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -80.586825
    East_Bounding_Coordinate: -80.500731
    North_Bounding_Coordinate: 24.954815
    South_Bounding_Coordinate: 24.885574
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 21-Jul-2016
    Ending_Date: 08-Dec-2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector, tabular and raster 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.
    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?
    Entity_and_Attribute_Overview:
    The detailed attribute descriptions for the stability data tables and maps are provided in the included data dictionaries (StabilityCategories_DataDictionary.pdf, StabilityTables_DataDictionary.pdf, and HabitatTypes_DataDictionary.pdf). These metadata are not complete without these files.
    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)
    • Kelly A. Murphy
    • Kimberly K. Yates
  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, Florida
    United States

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

Why was the data set created?

These data were used to identify areas of seafloor elevation stability and instability, from 2016 to 2017, at Crocker Reef, FL.

How was the data set created?

  1. From what previous works were the data drawn?
    2016-2017 Crocker Reef elevation-change points (source 1 of 1)
    Kimberley K. Yates, David G. Zawada, Stephanie R. Arsenault, and Zachery W. Fehr, 20190801, Seafloor Elevation Change From 2016 to 2017 at Crocker Reef, Florida Keys-Impacts From Hurricane Irma: U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    Type_of_Source_Media: Elevation-change data
    Source_Contribution:
    The original elevation-change points containing the calculated elevation change from 2016 to 2017 at Crocker Reef, FL.
  2. How were the data generated, processed, and modified?
    Date: 2020 (process 1 of 13)
    Step 1: The original 2016-2017 Crocker Reef elevation-change points (2016_2017_CrockerReef_SeafloorStability_Points shapefile) were processed and published by Yates and others (2019). For more information on the elevation-change data processing steps, source elevation data, and elevation-change points, see Yates and others (2019). Horizontal coordinates are referenced to the Universal Transverse Mercator (UTM) North American Horizontal Datum of 1983 (NAD83) National Spatial Reference System of 2007 (NSRS2007) National Readjustment and vertical coordinates are referenced to the North American Vertical Datum of 1988 (NAVD88), GEOID12B geoid model.
    Date: 2020 (process 2 of 13)
    Step 2: An elevation-change surface model was created in Esri ArcGIS Desktop Advanced version 10.6 (ArcMap) using the calculated elevation-change (Diff_m) points from the 2016_2017_CrockerReef_SeafloorStability_Points shapefile and methods of Yates and others (2017). The TIN was created using the “Create TIN (3D Analyst)” tool by specifying the 2016_2017_CrockerReef_SeafloorStability_Points shapefile as the “Input Feature Class”, Diff_m as the “Height Field” and Mass_Points as the “Type”, creating the 2016_2017_CrockerReef_SeafloorStability_TIN file. The 2016_2017_CrockerReef_SeafloorStability_TIN file was delineated using the “Delineate TIN Data Area (3D Analyst)” tool by specifying the 2016_2017_CrockerReef_SeafloorStability_TIN file as the “Input TIN”, a “Maximum Edge Length” of 2.828428 (hypotenuse of a triangle with 2-meter (m) legs) and the “Method” set to ALL. The delineated 2016_2017_CrockerReef_SeafloorStability_TIN was then clipped to the extent of the 2016 and 2017 DEMs using the “Edit TIN (3D Analyst)” tool with the following parameters: “Input TIN”: 2016_2017_CrockerReef_SeafloorStability_TIN file; “Input Features Class”: 2016-2017 geometric intersection footprint; “Height Field”: None; “Tag Field”: None; and “Type”: Hard clip. This step was required to remove unwanted triangles that spanned data gaps in the original DEMs used to generate the 2016_2017_CrockerReef_SeafloorStability_Points shapefile. For information on how to generate a geometric intersection between the 2016 and 2017 DEMs, see Yates and others (2017 and 2019).
    Date: 2020 (process 3 of 13)
    Step 3: The 2016_2017_CrockerReef_SeafloorStability_TIN file was classified into five stability categories using a defined stability threshold to identify areas of stability and instability. The stability threshold is the total root mean square error (RMSE) calculated for the 2016-2017 Crocker Reef elevation-change points using the vertical uncertainty of the 2016 and 2017 DEMs. A total RMSE of 0.21 m was calculated and rounded up to create a conservative stability threshold of 0.25 m that was applied to the TIN. See Yates and others (2017) for methods on calculating the RMSE. Based on the specified stability threshold of 0.25 m, the following five stability categories were identified: Stable: 0.0 m to ±0.24 m or 0.0 m to ±0.49 m; Moderately stable: ±0.25 m to ±0.49 m; Moderately unstable: ±0.50 m to ±0.74 m; Mostly unstable: ±0.75 m to ±0.99 m; and Unstable: ±1.00 m to Max/Min elevation change. Category boundaries use the pattern of “lower bound < or = x < upper bound” to avoid inclusion of individual elevation-change values in multiple categories. The categories were assigned based on the absolute value of the elevation-change values. For example, values within ±0.24 m of change were classified as Stable.
    Date: 2020 (process 4 of 13)
    Step 4: The 2016_2017_CrockerReef_SeafloorStability_TIN file was opened in ArcMap and the “Layer Properties” window was opened by double clicking the TIN in the “Table of Contents”. Within the “Symbology” tab, “Show: Elevation” was enabled, and “Classification Classes” was set to 10. To specify the bin values, “Classify” was selected within the “Classification” window, and the following “Break Values” were used to classify and bin the elevation-change values into ten classes: -0.994999 (class1); -0.744999 (class 2); -0.494999 (class 3); -0.244999 (class 4); 0 (class 5); 0.244999 (class 6); 0.494999 (class 7); 0.744999 (class 8); 0.994999 (class 9); and maximum positive elevation-change value (class 10). The “Break Values” were based on the 0.25 m stability threshold, with each class increasing in increments of 0.24 m up to ±1 m of change. Classes 4, 5 and 6 represent the stable elevation-change values with no change detected (Stable), classes 1 and 10 represent the unstable elevation-change values with change greater than ±1 m (Unstable), and the remaining classes represent the elevation-change values in between (Moderately stable through Mostly unstable).
    Date: 2020 (process 5 of 13)
    Step 5: The color symbology of the classes listed in the “Table of Contents” were changed to represent each stability category. A color gradient of red, gray, and blue shades was applied to the binned TIN to distinguish the stability level of each elevation-change value and distinguish areas of erosion and accretion. Both positive and negative elevation-change values that fell within the Stable category were colored gray. However, red and blue shades were applied to elevation-change values that fell within categories Moderately stable through Unstable to distinguish areas of erosion and accretion. Blue shades were applied to elevation-change values with positive elevation change (accretion) and red shades were applied to elevation-change values with negative elevation change (erosion). Lighter shades indicate the smallest amount of change while darker shades indicate the largest amount of change.
    Date: 2020 (process 6 of 13)
    Step 6: Additionally, the 2016-2017 Crocker Reef elevation-change points were classified into the five stability categories. The process was similar to the methods described in steps 3-5; however, the “Break Values” were defined differently because the method for binning points is different than delineating break points for a TIN in ArcMap. The 2016_2017_CrockerReef_SeafloorStability_Points shapefile was opened in ArcMap and the “Layer Properties” window was opened by double clicking the points in the “Table of Contents”. Within the “Symbology” tab, “Show: Quantities” was expanded, “Graduated Colors” was selected, “Value” was set to the attribute containing the elevation-change values (Diff_m) and “Classification Classes” was set to 10. The maximum sample size was reached. To change the sample size, “Classify” was selected within the “Classification” window, and the “Data Sampling” window was opened by selecting “Sampling”. Within the “Data Sampling” window, “Maximum Sample Size” was set to the total number of points, 8,402,223. The following “Break Values” were used to classify and bin the Diff_m values into ten classes: -0.995 (class 1); -0.745 (class 2); -0.495 (class 3); -0.245 (class 4); 0 (class 5); 0.244999 (class 6); 0.494999 (class 7); 0.744999 (class 8); 0.994999 (class 9); and max positive Diff_m value (class 10). The remaining steps to change the color symbology are the same as described in step 5.
    Date: 2020 (process 7 of 13)
    Step 7: The above process steps were repeated four times using different stability categories to represent a total of five different resolutions of elevation-change stability maps. The same color scheme was used for each resolution map. The above stability categories and “Break Values” described in Steps 3-6 represent the highest resolution map, 5th order. The remaining four resolutions of maps (1st through 4th order) required different “Break Values” and stability category ranges. The specific parameters for each resolution map are described in steps 8 through 11.
    Date: 2020 (process 8 of 13)
    Step 8: The 4th order resolution map was generated for the 2016_2017_CrockerReef_SeafloorStability_TIN file using the following eight “Break Values”: -0.744999, -0.494999, -0.244999, 0, 0.244999, 0.494999, 0.744999, and max positive elevation-change value. The following eight “Break Values” were used for the 2016_2017_CrockerReef_SeafloorStability_Points shapefile: -0.745, -0.495, -0.245, 0, 0.244999, 0.494999, 0.744999, and max Diff_m value. The four associated stability categories for both are as follows: Stable: 0.0 m to ±0.24 m, Moderately stable: ±0.25 m to ±0.49 m, Moderately unstable: ±0.50 m to ±0.74 m, Unstable: ±0.75 m to Max/Min elevation change. The 4th order resolution maps combine the Mostly unstable values into the Unstable category.
    Date: 2020 (process 9 of 13)
    Step 9: The 3rd order resolution map was generated for the 2016_2017_CrockerReef_SeafloorStability_TIN file using the following six “Break Values”: -0.494999, -0.244999, 0, 0.244999, 0.494999, and max positive elevation-change value. The following six “Break Values” were used for the 2016_2017_CrockerReef_SeafloorStability_Points shapefile: -0.495, -0.245, 0, 0.244999, 0.494999, and max positive Diff_m value. The three associated stability categories for both are as follows: Stable: 0.0 m to ±0.24 m, Moderately stable: ±0.25 m to ±0.49 m, Unstable: ±0.50 m to Max/Min elevation change. The 3rd order resolution maps combine the Moderately unstable and Mostly unstable values into the Unstable category.
    Date: 2020 (process 10 of 13)
    Step 10: The 2nd order resolution map was generated for the 2016_2017_CrockerReef_SeafloorStability_TIN file using the following three “Break Values”: -0.494999, 0.494999, and max positive elevation-change value. The following three “Break Values” were used for the 2016_2017_CrockerReef_SeafloorStability_Points shapefile: -0.495, 0.494999, and max positive Diff_m value. The two associated stability categories for both are as follows: Stable: 0.0 m to ±0.49 m and Unstable: ±0.50 m to Max/Min elevation change. The 2nd order resolution maps combine the Moderately stable values into the Stable category, and the Moderately unstable and Mostly unstable values into the Unstable category.
    Date: 2020 (process 11 of 13)
    Step 11: The 1st order resolution map was generated using the same “Break Values” and stability category ranges as the 2nd order resolution map. However, both positive and negative values that fell within the Unstable category were colored dark red regardless of being negative or positive to depict only stable and unstable areas regardless of gain or loss in elevation.
    Date: 2020 (process 12 of 13)
    Step 12: Using Microsoft Excel 2016, average elevation changes and standard deviations calculated by the USGS SPCMSC for each habitat found within the 2016-2017 elevation-change points data extent were entered into a table and color coded based on the defined stability colors for each map resolution. For information on how to calculate elevation-change statistics by habitat type, see Yates and others (2017 and 2019).
    Date: 2020 (process 13 of 13)
    Step 13: Map packages (.mpk) containing a map document and the data it contains were created for each resolution map. Each map document contains the habitat map and the binned and color coded 2016_2017_CrockerReef_SeafloorStability_Points shapefile and 2016_2017_CrockerReef_SeafloorStability_TIN file. For users that have access to ArcMap, the map packages can be downloaded and opened to display the habitat types and binned points and TIN for each resolution. The individual contents of the map packages are also provided in this data release, including layer files that store the symbology information for each resolution of the seafloor stability points and TIN. The layer files can be applied to the stability points or TIN in ArcMap within the “Symbology” tab of the “Layer Properties” window.
  3. What similar or related data should the user be aware of?
    Yates, Kimberly K., Zawada, David G., Arsenault, Stephanie R., and Fehr, Zachery W., 20190801, Seafloor Elevation Change From 2016 to 2017 at Crocker Reef, Florida Keys—Impacts From Hurricane Irma: U.S. Geological Survey data release doi:10.5066/P9JI465S, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    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:

    Organization, International Hydrographic, 2008, IHO Standards for Hydrographic Surveys: International Hydrographic Bureau, 4, quai Antoine 1er B.P. 445 - MC 98011 MONACO Cedex Principauté de Monaco.

    Online Links:

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

  1. How well have the observations been checked?
    Datasets were visually inspected by USGS staff in Esri ArcGIS Desktop Advanced version 10.6 for identification of data inconsistencies.
  2. How accurate are the geographic locations?
    For the 2016 lidar DEM used to produce the point dataset, the data positions were obtained using post-processed kinematic global positioning system (KGPS) methods. The horizontal accuracy of the data is better than plus or minus 1.0 m; Quantitative Value: 1.0 m. The 2017 multibeam data used to produce the point dataset were collected and processed to meet or exceed International Hydrographic Organization (IHO) Special Order Standards for positioning and depth (IHO, 2008).
  3. How accurate are the heights or depths?
    For the 2016 lidar DEM used to produce the point dataset, 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 data is better than plus or minus 0.15 m; Quantitative Value: 0.15 m. The 2017 multibeam data used to produce the point dataset were collected and processed to meet or exceed IHO Special Order Standards for positioning and depth (IHO, 2008).
  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 (2019) 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:
Please note the very large files and ensure you have the adequate computing compacity to access these files.
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?
  5. What hardware or software do I need in order to use the data set?
    Users must have access to Esri ArcGIS Desktop Advanced (ArcMap) version 10.6 or later to open the map packages provided in this data release.

Who wrote the metadata?

Dates:
Last modified: 25-May-2021
Metadata author:
Kimberly K. Yates
Southeast Region: St. Petersburg Coastal and Marine Science Center
Research Oceanographer
600 4th Street South
St. Petersburg, Florida
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/2016_2017_CrockerReef_stability_metadata.faq.html>
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