Mark Hansen 2000 St. Petersburg, FL U.S. Geological Survey http://sofia.usgs.gov/projects/bathymetry/ 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. 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 had 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. This project was completed in 1999. 1889 1999 ground condition Complete Unknown -81.11667 -80.36667 25.25 24.733333 none bathymetry circulation model hydrology mapping SANDS sediment dynamics System for Accurate Nearshore Depth Surveying none Florida Bay Everglades National Park Florida Keys Florida Miami-Dade County Monroe County Central Everglades Blackwater Sound Buchanan Key Calusa Keys Clive Key Flamingo Grassy Key Joe Bay Lake Ingraham East Long Key Lower Matecumbe Key Madeira Key Rock Harbor Sandy Key Schooner Key Tavernier Westlake Upper Matecumbe Key Pelican Keys Plantation Key none The U.S. Geological Survey must be referenced as the originator of the data from this project in any future products or research derived from these data. Mark Hansen U.S. Geological Survey Oceanographer 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/intro.html location of data collection area GIF Nancy T. DeWitt assisted in the bathymetric surveys and data processing. L. Thornton processed the historical data and provided GIS support. Hansen, Mark >DeWitt, Nancy T. 2000 USGS Open-File Reports OFR 00-347 St. Petersburg, FL U.S. Geological Survey http://sofia.usgs.gov/publications/ofr/00-347/ not applicable not available 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. 0.05 GPS data was processed with Jet Propulsion Laboratory GIPS software. 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. 0.1 GPS data was processed with Jet Propulsion Laboratory GIPS software. 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 U.S. 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. 2000 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 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 1890 and 1990 trackline data The data have no explicit or implied guarantees. ASCII http://sofia.usgs.gov/publications/ofr/00-347/ Data is available from the SOFIA website in OFR 00-347 none 20040415 Jo Anne Stapleton U.S. Geological Survey mailing address

521 National Center

Reston VA 20192 USA 703 648-4592 703 648-4614 jastapleton@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998