Attenuation Factor model results for Upper Floridan aquifer vulnerability to Bromacil and Ethylene Dibromide

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Frequently anticipated questions:


What does this data set describe?

Title:
Attenuation Factor model results for Upper Floridan aquifer vulnerability to Bromacil and Ethylene Dibromide
Abstract:
This dataset includes Attenuation Factor (AF; Rao and others, 1985) model results for Upper Floridan aquifer vulnerability to Bromacil and 1,2-Dibromoethane or Ethylene Dibromide (EDB). The AF value serves as an index for assessing the transport of pesticide mass from the vadose zone. The AF model setup requires the input of raster soil bulk density, soil organic carbon content, soil field capacity, soil air filled porosity, recharge to the aquifer, depth to groundwater, the pesticide sorption coefficient, pesticide Henry's Law Constant, and pesticide half-life. These variables were entered into the AF equation using the raster calculator tool in ArcGIS. The resulting AF values are dimensionless and range between 0 and 1. A value of 1 indicates that all of the pesticides in the vadose zone will leach into the groundwater; conversely, a value of 0 suggests that no pesticides will leach into the groundwater.
Supplemental_Information:
A downloadable version of the final dataset is provided in GeoTIFF file format with 10-meter resolution.
  1. How might this data set be cited?
    Douglas, Steven H., 20170828, Attenuation Factor model results for Upper Floridan aquifer vulnerability to Bromacil and Ethylene Dibromide: U.S. Geological Survey Data Release doi:10.5066/F7S46QTV, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -83.252177
    East_Bounding_Coordinate: -80.829948
    North_Bounding_Coordinate: 29.695895
    South_Bounding_Coordinate: 26.572896
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2017
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: 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 Raster data set. It contains the following raster data types:
      • Dimensions 19397 x 32005, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      The map projection used is USA_Contiguous_Albers_Equal_Area_Conic_USGS_version.
      Projection parameters:
      Standard_Parallel: 29.5
      Standard_Parallel: 45.5
      Longitude_of_Central_Meridian: -96.0
      Latitude_of_Projection_Origin: 23.0
      False_Easting: 0.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 10.0
      Ordinates (y-coordinates) are specified to the nearest 10.0
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    af_model.tif
    GeoTIFF file that includes attenuation factor model results for the Upper Floridan aquifer vulnerability to Bromacil and 1,2-Dibromoethane or Ethylene Dibromide (EDB). (Source: USGS)
    OID
    Internal feature number. Sequential unique whole numbers that are automatically generated. (Source: Esri)
    Range of values
    Minimum:0
    Maximum:4
    Value
    AF reclassified vulnerability class values. 1 = Very Low Vulnerability, 2 = Low, 3 = Medium, 4 = High, 5 = Very High. (Source: USGS)
    ValueDefinition
    1Very Low Vulnerability
    2Low Vulnerability
    3Medium Vulnerability
    4High Vulnerability
    5Very High Vulnerability
    Count
    Number of cells (Source: Esri)
    Range of values
    Minimum:25309776
    Maximum:73913452

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Steven H. Douglas
  2. Who also contributed to the data set?
    U.S. Geological Survey and University of South Florida St. Petersburg
  3. To whom should users address questions about the data?
    Cherokee Nation Technologies contracted to the U.S. Geological Survey
    Attn: Steven H. Douglas
    600 4th St S
    St. Petersburg, FL

    727-502-8134 (voice)
    sdouglas@usgs.gov

Why was the data set created?

This dataset was generated from the Attenuation Factor model to test the model's ability to indicate groundwater vulnerability to pesticides in the Southwest Florida Water Management District (SWFWMD).

How was the data set created?

  1. From what previous works were the data drawn?
    DISTRICT (source 1 of 8)
    Southwest Florida Water Management District, 20090206, District Polygon Boundary: Southwest Florida Water Management District, Brooksville, FL.

    Online Links:

    Type_of_Source_Media: digital
    Source_Contribution:
    Water management district boundaries dataset was used as the study area extent that the other layers were clipped to.
    SIM3182 (source 2 of 8)
    U.S. Geological Survey, 20111117, Potentiometric Surface of the Upper Floridan Aquifer in Florida and in Parts of Georgia, South Carolina, and Alabama, May – June 2010: U.S. Geological Survey, Orlando, FL.

    Online Links:

    Type_of_Source_Media: digital
    Source_Contribution:
    This vector point file of potentiometric surface was interpolated to calculate the depth to groundwater variable in the Attenuation Factor model equation.
    FLIDAR_MOSAIC_M (source 3 of 8)
    Florida Geographic Data Library, 201301, Florida Digital Elevation Model (DEM) Mosaic - 5-Meter Cell Size - Elevation Units Meters (FGDC): University of Florida GeoPlan Center, Gainesville, FL.

    Online Links:

    Type_of_Source_Media: digital
    Source_Contribution:
    The 5-meter DEM was used as the input surface elevation that was used to create the depth to groundwater variable.
    SWFWMD (source 4 of 8)
    Mapping and GIS Section, Southwest Florida Water Management District, 2002, Aquifer Recharge/Discharge data from USGS 2002 Model: Southwest Florida Water Management District, 2379 Broad Street, Brooksville, FL 34604-6899.

    Online Links:

    Type_of_Source_Media: digital
    Source_Contribution:
    Aquifer recharge/discharge was used as the recharge variable in the Attenuation Factor model equation.
    Pesticide Half-Life (t1/2) (source 5 of 8)
    Mackay, D., Shiu, W.Y., Ma, K.C., and Lee, S.C., 20060314, Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals Volume II, Second Edition.

    Type_of_Source_Media: print
    Source_Contribution:
    The half-life of EDB in groundwater was used as the half-life variable in the Attenuation Factor model equation.
    Henry's Constant (Kh) (source 6 of 8)
    Staudinger, J., and Roberts, P.V., 20010626, A critical compilation of Henry's law constant temperature dependence relations for organic compounds in dilute aqueous solutions..

    Online Links:

    Type_of_Source_Media: digital
    Source_Contribution:
    The EDB Henry's law constant was used as the Henry's law constant variable in the Attenuation Factor model equation.
    Sorption Coefficient (Koc) (source 7 of 8)
    Delle Site, A., 2001, Factors affecting sorption of organic compounds in natural sorbent/water systems and sorption coefficients for selected pollutants. A review..

    Type_of_Source_Media: print
    Source_Contribution:
    The EDB sorption coefficient was used as the sorption coefficient of pesticides on organic matter variable in the Attenuation Factor model equation.
    SSURGO (source 8 of 8)
    U.S. Department of Agriculture, Natural Resources Conservation Service, 2015, USDA-NRCS Soil Survey Geographic (SSURGO 2.2): Bulk Density, Organic Carbon Content, Field Capacity, and Porosity: USDA/NRCS - National Geospatial Center of Excellence, Fort Worth, TX.

    Online Links:

    Type_of_Source_Media: digital
    Source_Contribution:
    Bulk density (BD), Organic Carbon Content (OC), Field Capacity (FC), and Porosity (AC) were used as variables in the Attenuation Factor model equation
  2. How were the data generated, processed, and modified?
    Date: 2015 (process 1 of 5)
    Tabular and map Soil Survey Geographic Database SSURGO data for Florida were downloaded through the U.S. Department of Agriculture (USDA) Geospatial Data Gateway. Descriptions for the SSURGO classes are available at the Soil Survey website http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054253. SSURGO metadata is available at: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053631. The polygon shapefiles were joined to the tabular files within the SSURGO file geodatabase. The first join to be made uses the “mukey” field as the common identifier to join the cokey field from the “component” table. The second join to be made uses the cokey field as the common identifier to join the om_r (organic carbon content), dbthirdbar_r (bulk density), awc_r (field capacity), and wsatiated_r (porosity) field from the “CHorizon” table. The Florida shapefiles were clipped to the SWFWMD boundaries, using the clip tool in ArcGIS and the polygon shapefile, DISTRICT, as the boundary. The variables are expressed as a percent or fraction of the total volume. If the original data from SSURGO is expressed as floating-point decimal values between 0 and 1 then they were converted to values between 1 and 100 by adding a new field to the raster in the attribute table and using the field calculator to multiply the original values by 100. Bulk density was converted from g/cm3 to kg/m3 using the field calculator and by multiplying the bulk density values by 1000. The final polygon shapefile was converted to 10 meter raster GeoTiffs using the Polygon to Raster tool and selecting the new field with values 1 to 100 as the new raster values. Person who carried out this activity:
    Steven H. Douglas
    Cherokee Nation Technologies contracted to the U.S. Geological Survey
    600 4th St S
    St Petersburg, FL

    727-502-8134 (voice)
    sdouglas@usgs.gov
    Date: 2015 (process 2 of 5)
    Depth to groundwater was created by clipping the USGS potentiometric well points shapefile (Kinnaman and Dixon, 2011) to the SWFWMD study area extent. The potentiometric surface was calculated by interpolating the points with the Inverse Distance Weighted tool in ArcGIS and using the default settings. Finally, depth to groundwater was created by subtracting the potentiometric surface from the FLIDAR_MOSAIC_M DEM value using the raster calculator tool.
    Date: 2015 (process 3 of 5)
    Henry's law constant, half-life, and sorption coefficient raster layers were created by making three copies of the bulk density raster from the SSURGO data-set. Using the ArcGIS field calculator the values for all cells in the study area were changed to the corresponding variable value to create the constant raster variable.
    Date: 2015 (process 4 of 5)
    The recharge polygon shapefile, SWFWMD, was converted to a 10-meter raster GeoTiff, using the Polygon to Raster tool in ArcGIS.
    Date: 2015 (process 5 of 5)
    The Attenuation Factor model equation described by Rao and others (1985), was constructed using the Raster Calculator tool in ArcMap. The resulting AF values range between 0 and 1 and were divided into 5 classes, using the reclassify tool in ArcGIS, based on the standard deviation: very low (less than 0.3), low (between 0.3 and 0.522), medium (between 0.522 and 0.742), high (between 0.742 and 0.962), and very high (greater than or equal to 0.962).
  3. What similar or related data should the user be aware of?
    Rao, P.S.C., Hornsby, A.G., and Jesup, R.E., 1985, Indices for ranking the potential for pesticide contamination of groundwater: Proceedings of the Soil and Crop Science Society of Florida, Florida.

    Douglas, S., Dixon, B., and Griffin, D., Unknown, Assessing intrinsic and specific vulnerability models ability to indicate groundwater vulnerability to groups of similar pesticides: a comparative study: Physical Geography, Philadelphia, PA.


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

  1. How well have the observations been checked?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    No formal horizontal positional accuracy tests were conducted.
  3. How accurate are the heights or depths?
    A formal accuracy assessment of the vertical positional information in the data-set has either not been conducted, or is not applicable.
  4. Where are the gaps in the data? What is missing?
    Data-set is considered complete for the information presented, as described in the abstract.
  5. How consistent are the relationships among the observations, including topology?
    Raster values were checked for consistency with expected values.

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. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    Cherokee Nation Technologies contracted to the U.S. Geological Survey
    Attn: Steven Douglas
    600 4th St S
    St Petersburg, FL

    727-502-8134 (voice)
    sdouglas@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The data have been approved for release and publication by the U.S. Geological Survey (USGS). Although the data have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released on the condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from authorized or unauthorized use. Although the data have been processed successfully on a computer system at the 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 and/or contained herein. Users of the data are advised to read all metadata and associated documentation thoroughly to understand appropriate use and data limitations.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 28-Aug-2017
Metadata author:
Cherokee Nation Technologies contracted to the U.S. Geological Survey
Attn: Steven H. Douglas
600 4th St S
St. Petersburg, FL

727-502-8134 (voice)
sdouglas@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/AF_metadata.faq.html>
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