Project Proposal for 1998
Program: FRAGILE ENVIRONMENTS
Project Title:
HIGH-RESOLUTION BATHYMETRY OF FLORIDA BAY
Location of Study Area: Florida Bay
Project Start Date: FY95
Project End Date: FY99
Project Number: 7242-37650
Project Chief:
Mark Hansen
Region/Division/Team/Section: Eastern/Geologic/St. Petersburg
E-mail:
mhansen@usgs.gov
Phone: 813-893-3100 ext 3036
Fax: 813-893-3333
Mailing Address:
600 4th St. S.
St. Petersburg, FL 33701
Program Element(s)/Task(s) 6.2
Panel:
Collaborators, Clients: US Army Corps of Engineers - Numerical modeling
; NOAA - Mapping
The primary users of the data will be researchers who are applying numerical models to the Bay to
understand water circulation patterns and gradients in sediment transport. These efforts are directly
related to water quality issues in the Bay. Circulation models are being developed and applied by WES
and sediment transport models are being applied by USGS researchers. The updated bathymetry will also
serve as a reference for future research in the Bay.
Project Summary: Detailed, high-resolution maps of Florida Bay mudbank
elevations are needed to
understand sediment dynamics and provide input into circulation models. The bathymetry of Florida Bay has
not been systematically mapped in nearly 100 years, and some shallow areas have never been mapped. An
accurate, modem bathymetric survey will provide a baseline for assessing future sedimentation rates in the
Bay, and a foundation for developing a sediment budget. Due to the shallow depths of the Bay, an updated
bathymetry grid (digitally derived from the survey) is critical for circulation models.
Project Justification: Numerical circulation and sediment transport
models being developed for the South
Florida Ecosystem Restoration Program will be used to address water quality issues in Florida Bay.
Application of these models is complicated due to the complex sea-floor topography (basin/mudbank
morphology) of the Bay. The only complete topography data set of the Bay is 100 years old. Consequently,
an accurate and modern sea-floor or 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. Previous research suggests that the mudbanks are dynamic features
which migrate, accrete and erode. Less is known about the sedimentation rates in the basins. Some experts
suggest the basins are filling, in association with sea-level rise, while others suggest the basins are
deepening relative to sea-level. This study will produce a detailed bathymetric data set of Florida Bay in
order to help assess sedimentation rates and provide numerical modelers with an accurate bathymetry map.
Project Objectives: The objective of this research is 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. This information will be provided to other researchers
involved in the South Florida Ecosystem Restoration Program so they can better address the water quality
issues of Florida Bay.
Overall Strategy, Study Design, and Planned Major Products: The strategy
is to systematically map the bathymetry in Florida Bay in order aid in the assessment of Bay
sedimentation rates and to provide an accurate sea-floor surface for numerical models. The Bay will be
mapped using a shallow draft boat equipped with a high-precision GPS coupled with a high-precision
depth sounder. Data will be collected on a USGS 7.5 min quad-by-quad basis proceeding westward from
Blackwater Sound. Sounding trackline spacing will vary depending upon the relief of the sea-floor, i.e.
closer spacing in near mud banks - wider spacing in the basins. Digital sea-floor grids will be produced
from the trackline data. Historical bathymetric data (1890) will be obtained from NOS archives,
digitized, and entered into a GIS. Digital comparisons will be made between the historical data and the
new data. The project will produce both hardcopy and digital map products and professional papers.
Historical and modern bathymetric maps will be produced as well as maps of bathymetric change.
Digital maps will be available on the Internet and distributed on CD-ROM's. CD-ROM format will
conform to ARC/View and SDTS standards.
Overall: The parts of the Bay which are accessible by a shallow
draft boat will be mapped using the
System for Accurate Nearshore Depth Surveying (SANDS). This system, developed by the USGS,
utilizes geodetic differential Global Positioning System (GPS) receivers, a digital fathometer, a digital
heave/roll/pitch sensor, and a shallow draft boat. The system is accurate to ~10 cm vertically, ~4 cm
horizontally, and can collect data in water depths as shallow as 50 cm. In order to achieve this accuracy,
the boat must not rove more than 10 km from any one GPS reference receiver. Therefore, approximately
10 new ground control points (with 1-2 cm accuracy) will be established throughout the Bay for use as
reference receiver sites. Soundings will be referenced to the GRS80/NAD83 horizontal datum and
NAVD88 vertical datum (via the NOS GEODID96 geoid model). For areas not accessible by boat, mud
bank tops and sensitive sea-grass areas, other non-intrusive (remote sensing based) methods must be
employed to fully map the bathymetry of the Bay. One non-intrusive technique to map the boat
inaccessible areas is the US Army Corps of Engineers SHOALS helicopter LIDAR system. Another
method utilizes vertical photography or imagery in combination with water stage data to detennine the
elevations of the mud banks. These two techniques and others are being investigated at this time.
Utilizing a non-intrusive method(s) in conjunction with the SANDS system will provide basin and mud
bank elevations for the entire Bay.
Data collected will be checked for errors then entered in a sophisticated contouring package (CPS3) for
contour and digital grid generation. This information will then be passed into ARC/Info for map
production and data archiving. All raw (field) data will be stored and archived on magnetic-optical disks.
Bathymetric survey data will continue to be collected through 1998. Preliminary hard copy and digital
maps will be produced on an annual basis. Data will be provided to clients after it has been internally
reviewed for accuracy.
Historical bathymetric data will be obtained from NOS historical archives. The only complete historical
bathymetric data of the Bay is from the 1890 time period. All sounding will be digitized using standard
digitizing practices. In order to compare this data set to the modern it must be projected into a modern
horizontal datum (NAD83). Projecting the historical data into a modern datum is not straightforward as
there was no national horizontal datum before 1920. However, the USGS has obtain a unique data set of
control points from NOS archives which have both the 1890 positions and NAD83 positions. This
information allow us to accurately compare the historical to the modern.
Historical, moderm and change maps will be produced at a scale of 1:24000 and will conform to USGS I-
Map standards. Map production will be performed using ARC/Info and data archiving will comply with
SDTS standards.
Timeline:
FY98 Hansen -PI, Dewitt - Field Data Collection/Processing,
Thomton - GIS expert
Collect field data including establishing new ground control points when necessary.
Process field data.
Produce draft maps and digital grids of moderm data.
Complete digitization of historical data.
Produce draft maps of historical data.
Produce draft maps of sea-floor change.
Professional Paper - Use of SANDS for Mapping Florida Bay.
FY99 Hansen -PI, Dewitt - Field Data Collection/Proccssing, Thomton - GIS expert
Complete collection of field data including establishing new ground control points when necessary.
Process field data.
Produce final maps and digital grids of moderm data.
Produce final maps of historical data.
Produce final maps of sea-floor change.
Produce USGS Open File report - Summary of historical sea-floor change in Florida Bay.
Planned Deliverables/Products:
FY98 - All map products will
be in draft form
Modern sea-floor maps of Florida Bay at 1:24000 (7.5 min USGS Quadrangle) overlaid on DOQ
Digital grids of modem sea-floor bathymetry
Historical (1890) sea-floor maps of Florida Bay at 1:24000 (7.5 min USGS Quadrangle)
Sea-floor change maps (1890-199x) of Florida Bay at 1:24000 (7.5 min USGS Quadrangle)
FY99 - All map products will be in final form
Modem sea-floor maps of Florida Bay at 1:24000 (7.5 min USGS Quadrangle) overlaid on DOQ
Digital grids of modem sea-floor bathymetry
Historical (1890) sea-floor maps of Florida Bay at 1:24000 (7.5 min USGS Quadrangle)
Sea-floor change maps (1890-199x) of Florida Bay at 1:24000 (7.5 min USGS Quadrangle)
Planned Outreach Activities: The US Army Corps of Engineers (WES)
will receive digital sea-floor grids after they have been
reviewed internally for accuracy. The grids will be used for numerically modeling Bay water circulation
and sediment transport. In the past year, we have assisted (5.field days) NOAA in collecting water level
data using the SANDS system. NOAA is using our data to establish ground control for a variety of
research projects related to the South Florida Restoration Program. We plan to assist NOAA in the
future when requested.
Prior Accomplishments in Proposed Area of Work:
New Directions, Expansion of Continuing Project (if applicable): None
Accomplishments and Outcomes, Including Outreach:
Florida Bay has been
systematically surveyed from Buttonwood Sound to Calusa Key basin.
Four new ground control points were established.
All historical shoreline and bathymetric data of Florida Bay has been digitized.
NOAA has been provided field assistance for 5 days and processed water level data.
Deliverables, Products Completed:
FY97 products will be for
the area from Blackwater Sound to Calusa. Key basin. All map products will
be in draft form.
Modern sea-floor maps of Florida Bay at 1:24000 (7.5 min USGS Quadrangle).
Digital grids of modern sea-floor bathymetry.
Historical (1890) sea-floor maps of Florida Bay at 1:24000 (7.5 min USGS Quadrangle).
Sea-floor change maps (1890-199x) of Florida Bay at 1:24000 (7.5 min USGS Quadrangle).
Required Expertise:
FY98
oceanographer for Bathymetric surveys
Field Assistant for Bathymetric surveys/data processing
GIS experts for Historical data processing
FY99
Oceanographer for Bathymetric surveys
Field Assistant for Bathymetric surveys/data processing
GIS experts for Historical data processing
Names of Key Project Staff:
FY98
Mark Hansen l6pp
Nancy Dewitt 22pp
Lance Thornton 13pp
FY99
Mark Hansen 26pp
Nancy Dewitt 22pp
Lance Thornton 13pp
Major Equipment/Facility Needs:
The SANDS system is comprised of high-precision instrumentation valued at ~$150K, operated on a boat
worth ~$50K. This equipment has been provided to this project without incurring major equipment
purchase costs. The requested repair and replacement (R&R) funds are to cover the cost of R&R which
frequently occurs when instrumentation is subjected to vibration and humid salt air in a small boat.
FY98
$10K Small boat expenses
$15K Field/travel expenses
$20K Equipment repair and replacement
FY99
$5K Small boat expenses
$10K Field/travel expenses
$20K Equipment repair and replacement
$25K Map publication expenses
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