Mark Hansen 2000 version 1 map St. Petersburg, FL U.S. Geological Survey, Center for Coastal Studies http://sofia.usgs.gov/projects/bathymetry/ The map shows the tracklines for bathymetric data collected between 1995 and 1999 for Florida Bay. The areas on the map are linked to the corresponding data sets which contain values for X (easting), Y (northing), Z (elevation), and the RMS computed from Ashtech PNAV software. The data set is labeled 1990 for easy comparison. The project duration was a decade. Detailed, high-resolution maps of Florida Bay mudbank elevations are needed to understand sediment dynamics and provide input into water quality and circulation models. The bathymetry of Florida Bay has not been systematically mapped in nearly 100 years, and some shallow areas of the bay have never been mapped. An accurate, modern bathymetric survey provides a baseline for assessing future sedimentation rates in the Bay, and a foundation for developing a sediment budget. Due to the complexity of the Bay and age of existing data, a current bathymetric grid (digitally derived from the survey) is critical for numerical models. Numerical circulation and sediment transport models being developed for the South Florida Ecosystem Restoration Program are being used to address water quality issues in Florida Bay. Application of these models is complicated due to the complex seafloor topography (basin/mudbank morphology) of the Bay. The only complete topography data set of the Bay is 100 years old. Consequently, an accurate, modern seafloor bathymetry map of the Bay is critical for numerical modeling research. A modern bathymetry data set will also permit a comparison to historical data in order to help access sedimentation rates within the Bay. The objective of this research was to collect new bathymetry for all of Florida Bay, digitize the historical shoreline and bathymetric data, compare previous data to modern data, and produce maps and digital grids of historical and modern bathymetry. 1995 1999 ground condition Complete None planned -81.11667 -80.36667 25.25 24.733333 none bathymetry hydrology mapping SANDS sediment dynamics System for Accurate Nearshore Depth Surveying ISO 19115 Topic Category environment imageryBaseMapsEarthCover inlandWaters oceans 007 010 012 014 Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, DC, National Institute of Standards and Technology United States US U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard 5-2): Washington, DC, NIST Florida FL Department of Commerce, 1990, Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas, FIPS 6-3, Washington, DC, National Institute of Standards and Technology Miami-Dade County Monroe County USGS Geographic Names Information System Blackwater Sound Buchanan Keys Calusa Keys Clive Key Flamingo Everglades National Park Grassy Key Joe Bay Long Key Lower Matecumbe Key Pelican Keys Plantation Key Rock Harbor Sandy Key Tavernier Upper Matecumbe Key West Lake none Central Everglades Madeira Key Schooner Key Lake Ingraham East Florida Keys none The U.S. Geological Survey must be referenced as the originator of the data set in any future products or research derived from these data. Mark Hansen U.S. Geological Survey mailing and physical address

600 Fourth Street South

St. Petersburg FL 33701 USA 727 803-8747 x 3036 727 803-2030 mhansen@usgs.gov http://sofia.usgs.gov/publications/ofr/00-347/1990tk.html location of 1990's tracklines GIF Nancy T. DeWitt assisted in the bathymetric surveys and data processing. L. Thornton processed the historical data and provided GIS support. The data are in ASCII text files Hansen, Mark DeWitt, Nancy T. 2000 report USGS Open-File Report OFR 00-347 St. Petersburg, FL U.S. Geological Survey http://sofia.usgs.gov/publications/ofr/00-347/ not applicable All data were processed and used to generate the bathymetric data points. For data format consistencies, RMS values for the 1890's data set are equal to 0.0. The horizontal positions of each data point were transformed from Latitude/Longitude to UTM (Zone 17) XY coordinates using NOAA/NGS software UTMSv1.0. 0.05 unavailable Vertical positions were converted from ellipsoid height to orthometric height using NOAA/NGS software GEOID96, where orthometric height is considered to be equal to NAVD88. According to NOAA tidal datum information, NAVD88 is approximately 0.41m (1.35 ft) above MLW in the Florida Bay area. The 1.35 feet average is calculated using the elevation information from several tidal benchmarks throughout the Florida Keys. These tidal benchmarks are published by the National Geodetic Survey and can be located on their website http://www.ngs.noaa.gov/cgi-bin/ngs_opsd.prl/. Five tidal benchmarks were chosen from four different U.S. Geological Quadrangle locations including Blackwater Sound, Plantation Key, Long Key and Grassy Key. The open-file report contains a table for quick reference of information for the five tidal benchmarks. To compare this data set with other depth information which is relative to MLW, e.g. NOAA nautical charts, 0.41 m (1.35 ft) is algebraically subtracted from each depth value or contour line. 0.01 not available Florida Bay was mapped by using a shallow-draft boat equipped with a high-precision Global Positioning System (GPS) coupled with a high-precision depth sounder. To accomplish this task, SANDS (System for Accurate Nearshore Depth Surveying) was developed by Mark Hansen and Jeff List of the US Geological Survey. SANDS utilizes differential GPS receivers, a digital fathometer, a heave-roll-pitch sensor, and a shallow-draft boat. The SANDS system is accurate to approximately 4 cm horizontally and 8 cm vertically and collects data in water depths as shallow as 30 cm. To achieve this accuracy, the boat's roving distance from any one GPS reference receiver location must be within a 10-kilometer radius. Data was collected on a USGS 7.5-minute quadrangle-by-quadrangle basis, proceeding westward from Blackwater Sound. The trackline spacing varied depending upon the relief of the sea floor; that is, closer spacing adjacent to mudbanks and wider spacing in the basins. Tracklines were surveyed in a north-south orientation, and crossings (intersecting tracklines) were surveyed in an east-west orientation. Crossing lines are critical because they served as a check on the accuracy of the system. In theory, data values at the crossing should be exactly the same. In reality, this is not always the case due to random errors of each sensor. Eighty-five percent of the crossings in this data set were within +/- 6 cm with the balance within +/- 20 cm. Ideally, crossings are made at the end of the survey day; however, some of the crossings were made months and even years after an area was initially surveyed. The results are very good considering the soft bottom characteristics of Florida Bay. Bathymetric positions for this study were derived using differential GPS techniques on 10-km baselines or less. One or more GPS reference stations (base stations) were continuously recording full-phase carrier data while the boat surveyed. A rover GPS receiver on the boat was simultaneously recording carrier information. Record epoch interval was 1 second for both base station and rover receivers. Precise positions for each epoch were computed using Ashtech Precise Differential GPS Navigation and Surveying (PNAV) v2.0 software. PNAV provides a root mean squared (RMS) value for each epoch. For this study, a RMS value of 0.08 cm or less was considered reasonable. An RMS value of 1.0 indicates that the GPS data ambiguities were unresolved, and that the depths were determined by a tie-line best-fit method. For data format consistencies, RMS values for the 1890's data set are equal to 0.0. The horizontal positions of each data point were transformed from Latitude/Longitude to UTM (Zone 17) XY coordinates using NOAA/NGS software UTMSv1.0. Vertical positions were converted from ellipsoid height to orthometric height using NOAA/NGS software GEOID96, where orthometric height is considered to be equal to NAVD88. According to NOAA tidal datum information, NAVD88 is approximately 0.41m (1.35 ft) above MLW in the Florida Bay area. The 1.35 feet average is calculated using the elevation information from several tidal benchmarks throughout the Florida Keys. These tidal benchmarks are published by the National Geodetic Survey and can be located on their website http://www.ngs.noaa.gov/cgi-bin/ngs_opsd.prl/. Five tidal benchmarks were chosen from four different U.S. Geological Quadrangle locations including Blackwater Sound, Plantation Key, Long Key and Grassy Key. To compare this data set with other depth information, which is relative to MLW, e.g. NOAA nautical charts, 0.41 m (1.35 ft) is algebraically subtracted from each depth value or contour line. Geodetic control in Florida Bay was lacking in number and geometric strength. In order to accomplish centimeter vertical accuracy, additional geodetic control needed to be established within the Bay. Thirteen new temporary ground-control points or benchmarks (surveyed to within 1 cm to 2 cm accuracy) were established throughout the Bay for use as reference receiver sites. The thirteen benchmarks were surveyed using Ashtech Z-12, 12 channel dual-frequency GPS receivers. Full-phase carrier data were recorded on each occupied benchmark in Ashtech proprietary BIN format with daily occupations ranging from 6 to 12 hours. BIN files were then converted to RINEX-2 format and position determined by the National Aeronautics and Space Administrations (NASA) Jet Propulsion Laboratory GIPSY system software. The GIPSY derived positions were provided in ITRF96 coordinate system for each (daily) occupation. Using National Oceanic and Atmospheric Administration/National Geodetic Survey (NOAA/NGS) software HTDPv2.3, ITRF96 positions were transformed to NAD83/GRS80 positions. The computed daily positions were then averaged to derive a final benchmark location and elevation. Daily outliers greater than 0.05cm (in the vertical component) from the average were not included in the final average. 199910 Nancy DeWitt U.S. Geological Survey Marine Geologist mailing address

600 Fourth Street South

St. Petersburg FL 33701 USA 727 803-8747 ext. 3058 727 803-2030 ndewitt@usgs.gov Florida Bay Universal Transverse Mercator 17 0.9996 -81 0 500000 0 Coordinate Pair 0.01 0.01 meters North American Datum of 1983 Geodetic Reference System 80 6378137 298.257 North American Vertical Datum of 1988 0.01 meters Explicit elevation coordinate included with horizontal coordinates The map shows the lines of data collection and each quad is linked to its corresponding data file. USGS personnel Heather S.Henkel U.S. Geological Survey mailing address

600 Fourth St. South

St. Petersburg FL 33701 USA 727 803-8747 ext 3028 727 803-2030 hhenkel@usgs.gov Florida Bay 1990's trackline map The data have no implied or explicit guarantees GIF http://sofia.usgs.gov/publications/ofr/00-347/1990tk.html Data may be downloaded from the SOFIA website None 20070611 Heather Henkel U.S. Geological Survey mailing and physical address

600 Fourth Street South

St. Petersburg FL 33701 USA 727 803-8747 ext 3028 727 803-2030 sofia-metadata@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998