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.
Source_Information:
Source_Citation:
Citation_Information:
Originator:
Kimberley K. Yates, David G. Zawada, Stephanie R. Arsenault, and Zachery W. Fehr
Publication_Date: 20190801
Title:
Seafloor Elevation Change From 2016 to 2017 at Crocker Reef, Florida Keys-Impacts From Hurricane Irma
Geospatial_Data_Presentation_Form: Shapefile
Publication_Information:
Publication_Place: St. Petersburg, FL
Publisher: U.S. Geological Survey
Online_Linkage: https://doi.org/10.5066/P9JI465S
Type_of_Source_Media: Elevation-change data
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20160721
Ending_Date: 20171208
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: 2016-2017 Crocker Reef elevation-change points
Source_Contribution:
The original elevation-change points containing the calculated elevation change from 2016 to 2017 at Crocker Reef, FL.
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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).
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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).
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
Process_Step:
Process_Description:
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).
Process_Date: 2020
Process_Step:
Process_Description:
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.
Process_Date: 2020
