Advanced GeoSpatial Inc. June, 2008 Alachua County Floridan Aquifer Protection Zones vector digital data withheld ACAVA_2008 The reduced resolution shapefile is a representation of the relative vulnerability map for the Floridan aquifer system within Alachua County or ACAVA. The original grid from, which this shapefile is derived, was calculated using the ArcSDM extension and applying the weights of evidence method. The reduced resolution grid was calculated using the Spatial Analyst extension and applying the Neighborhood tool Focal Statistics. A layer file with the correct symbology has been included with the grid. If for some reason that layer file is missing then the Less Vulnerable class is all values less than or equal to 90, Vulnerable is greater than 90 and less than or equal to 675, More Vulnerable is greater than 675. It should be noted that for the purposes of this project the lowest two classes, 'Less Vulnerable' and 'Vulnerable' were combined into the lowest class. Generalization of the ACAVA relative vulnerablity map for the Floridan aquifer system in Alachua County in order to support Aquifer Protection. en 2005 publication date Complete None planned -82.665589 -82.043645 29.945504 29.415255 2552502.740550 2746481.320550 159355.992679 348575.462679 ISO 19115 Topic Category Geoscientific Information Vulnerability Florida Floridan Aquifer System Alachua County none Maps generated as part of this project were developed by Advanced GeoSpatial Inc. (AGI) to provide Alachua County with support for an Aquifer Protection Zone Map Deliver an aquifer protection zone map based on ACAVA results that is directly applicable to land use and environmental regulatory decisions. Although efforts were made to ensure information in these maps is accurate and useful, neither Alachua County nor AGI assumes responsibility for errors in the information and does not guarantee that the data is free from errors or inaccuracies. Similarly, AGI and Alachua County assume no responsibility for consequences of inappropriate uses or interpretations of the data on these maps. Accordingly, these maps are distributed on an "as is" basis and the user assumes all risk as to their quality, results obtained from their use, and performance of the data. AGI and Alachua County further make no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its suitability for any particular purpose. The burden for determining suitability for use lies entirely with the end user. In no event shall AGI or Alachua County, or their respective employees have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the project results. AGI and Alachua County bear no responsibility to inform users of any changes made to this data. Anyone using this data is advised that resolution implied by the data may far exceed actual accuracy and precision. Because this data was developed and collected with Alachua County funding, no proprietary rights may be attached to it in whole or in part, nor may it be sold to Alachua County or other government agency as part of any procurement of products or services. Alachua County Environmental Protection Department mailing and physical address
201 SE 2nd Ave., Suite 201
Gainesville FL 32601 USA 352-264-6825 352-264-6852 Advanced GeoSpatial Inc. ESRI ArcCatalog 9.3.1.3500 Personal GeoDatabase Feature Class Process began by modifying the ACAVA results, first by converted the output results from a floating point grid into an integer grid by multiplying the original grid by 100,000 to remove the decimal places and maintain all of the significant digits. This has to be done since the focal statistics and nibble functions will only work with integer grids. Next removed the no data areas from the results (lakes and null soils) since these areas were affecting the generalization of the models. Using the NIBBLE command we assigned the nearest neighbor value to the no data areas. Because there were problems identified with the first ACAVA model and the input layer Head Difference, we derived a way to account for the "banked recharge" occurring in the southwest corner of the county. In recent aquifer vulnerability studies a new layer was developed to use "Recharge Potential". In Copeland et al. (1991), the area of the Brooksville Ridge in central Florida is defined as having higher recharge potential than adjacent areas. The Brooksville Ridge is chiefly composed of Undifferentiated Hawthorn Group sediments which are poorly to moderately consolidated clayey sands and silty clays (Scott et al., 2001). Recharge potential values were calculated for the study area by subtracting the USGS 2000 potentiometric surface of the FAS (USGS, 2001) from land surface elevation. Resulting recharge potential values from the study area range between 10 ft and 90 ft (relative to mean sea level) and can be discontinuous, deeply weathered and perforated by karst features. Where recharge potential is high, aquifer vulnerability is increased. To account for this higher recharge we clipped a part of the Brooksville Ridge by the county boundary and converted it into a grid. The Brooksville ridge boundary came from the "Physiographic Divisions of Florida" map. This map depicts the locations and names of physiographic units as defined by Dr. H.K. Brooks, the maps author. The grid was then given a vulnerability value that was considered to be high and then merged with the results. With the vulnerability map prepared an appropriate cell size for analysis was needed. Recent projects recommended that model results be applied on a local scale of greater than or equal to approximately 1.0 sq. mi. for statewide studies (Florida Aquifer Vulnerability Assessment) or approximately 0.75 sq. mi. for localized studies (Wekiva, Leon and Marion County Aquifer Vulnerability Assessments). Based on similarities to larger scale projects, AGI determined that the model results be used at the recommended scale 0.75 mi2, or an approximate 4,500-ft grid cell size. In other words, decisions using this tool made within a 0.75 mi2 area (approximate 4,500-ft x 4,500-ft area. This is the equivalent to an approximate cell size of 1,380 m. To smooth the results we used ΒΌ of that cell size or 345 m. Upon completion of the data layers and the selection of an analysis cell size we ran a focal statistics filter on the data set. The statistical filter was called a Focal Mean and it was run in a circular radius going out 12 cells. This means that it goes out from each cell that it is analyzing and calculates the average value for all of the cells in that 12 cell window. The result of this statistical analysis can be seen in the image below. The final output groups the two lower vulnerability classes, Vulnerable and Less Vulnerable, into one class. More information on focal statistics can be found below and parts of it were copied from the ArcGIS Desktop help. The generalized ACAVA Response Theme shapefile is a derivative of the relative vulnerability map for the Floridan Aquifer System in Alachua County. It was generalized using Foccal Statistics, a tool located in Neighborhood tools of the Spatial Analyst Toolbox and then converted into a shapefile for casual use by Alachua County. withheld Unknown Advanced GeoSpatial Inc Alan Baker Geologist and project manager mailing and physical address
1949 Raymond Diehl Rd.
Suite D
Tallahassee FL 32308 USA 850-580-4447 Metadata imported. withheld Metadata imported. withheld 20081006 Dataset copied. withheld 20081103 16230100 Vector Grid Cell 1939 1964 1 Simple FALSE 0 TRUE FALSE coordinate pair 0.010000 0.010000 survey feet North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 GCS_North_American_1983 NAD_1983_StatePlane_Florida_North_FIPS_0903_Feet Explicit elevation coordinate included with horizontal coordinates 0.010000 ACAVA_2008 relative vulnerablity multiplied by 100,000 Feature Class 0 OBJECTID OBJECTID OID 4 10 0 Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Feature geometry. Shape Shape Geometry 8 0 0 ESRI Coordinates defining the features. VulnZone VulnZone String 20 0 0 Shape.STArea() Shape.STArea() Double 0 0 0 Shape.STLength() Shape.STLength() Double 0 0 0 Florida Geological Survey mailing and physical address
Gunter Building MS #720
903 W. Tennessee St.
Tallahassee FL 32304-7700 USA 850-488-4191 850-488-8086 Downloadable Data 15.193 0.024 20100811 Florida Geological Survey James Cichon Hydrogeologist mailing and physical address
Gunter Building MS #720
903 W. Tennessee St.
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