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High Accuracy Elevation Data Collection

Project Proposal for 1999

Project title: High Accuracy Elevation Data Collection
Geographic area: South Florida Ecosystem Region
Project start date: November, 1994
Project end date: To be determined

Project chiefs: Greg Desmond
Region/Division/Team/Section: Eastern, NMD, Mapping Applications Center, Science and Applications Branch
Email: gdesmond@usgs.gov
Phone: 703/648-4728
Fax: 703/648-4165
Mail address: MS 521 National Center, Reston, VA 20192

Program: Integrated Natural Resource Science Program, South Florida Ecosystem

Program element(s)/task(s):
Element 2, Task 2.2- Land-surface marsh elevations
Element 5, Task 5.4- Ground-surface elevation and ground control for southwest Everglades National Park

Project summary:
Modeling of sheet flow and water surface levels in the wetlands of South Florida is very sensitive to changes in elevation due to the expansive and extremely low relief terrain. Hydrologists have determined the minimum vertical accuracy requirements of the elevation data for use as input to hydrologic models. As a result, elevation data with an accuracy of 15 centimeters or better are being collected in critical areas using new differential global positioning system (GPS) technology and data processing techniques.

Project objectives and strategy:
The main objective of this project is to collect accurate elevation data using state-of-the-art differential GPS technology covering regions specified by program hydrologists. These data will be made available for use as input to hydrological models being developed by the scientific community. Techniques are being used to collect and process elevation data that have a vertical accuracy of 15 cm or better referenced to the North American Vertical Datum of 1988 (NAVD88). The primary data collection strategy is to use the helicopter based Airborne Height Finder (AHF), developed during earlier phases of this project, to collect data and produce elevation points spaced approximately 400 meters apart throughout Everglades National Park and the surrounding region. It will also be necessary to expand the existing vertical geodetic control network for use as vertical reference points during AHF data collection operations.

Potential impacts and major products:
The elevation datasets being generated by this project are the most accurate ever produced for the Everglades and surrounding environs. These data will be used in the development of digital elevation models (DEMís), which in turn are used to parameterize hydrologic models to simulate and predict water flow direction, depth, velocity, and hydroperiod. Water resources and land management decisions will rely on these models, so it is imperative to use the most accurate elevation data available to achieve meaningful results.

Collaborators, clients:
The primary collaborators and clients of this project include Everglades National Park (ENP), South Florida Water Management District (SFWMD), and the Water Resources Division of USGS. The U.S. Army Corps of Engineers and the National Geodetic Survey (NGS) have also collaborated during various surveying and consulting phases of the project and will continue to do so. Plans are underway to work with NGS and others for the expansion of the vertical geodetic control network. It is anticipated that other ecosystem stakeholders, such as the agricultural industry, state and local government planning departments, environmental protection groups, and academia, will also utilize the data.

Time line (FY 1999 to project end):
The major tasks include completing the elevation dataset for the Southern Inland and Coastal System (SICS) model area, continuing work on other critical areas, and to extend the vertical geodetic control network. The deliverables are elevation point data and digital elevation models organized by 7.5 minute quadrangle. Key staff members include:
Vince Caruso- DEM processing
Ed Cyran- AHF engineer and field work project leader, data processing
Greg Desmond- project coordination
Bob Glover- data collection and processing
Chuck Henkle- data collection and processing (contractor)
Gordon Shupe- data collection and processing, quality control
Additional contractors will be determined for data collection and processing.

FY 1999 activities and products:
Work to be undertaken in FY99 is a continuation of the ongoing project. The procedure is to collect GPS data using geodetic quality GPS receivers with the AHF that are capable of receiving data beneath the helicopter rotor, at the same time that receivers are collecting GPS data at the reference control points. The AHF measures the offset distance between the GPS receiver and the ground surface. These data are processed using specialized software into 3-dimensional coordinates, which are then processed into DEMís.

FY 1999 outreach:
For the majority of the effort, client requirements and time lines are defined by Task Force hydrologists. The plan is to continue close coordination with the hydrologic modelers to stay abreast of, and remain responsive to elevation data requirements. A second South Florida Elevation Data Users Technical Exchange Meeting (please see FY98 Accomplishments) will be proposed. Presentations at professional conferences and the planned DOI South Florida Ecosystem Program Symposium are anticipated.

New directions or major changes for FY 1999 (if applicable):
Additional requirements for elevation data within the SICS model area will be added to the project. Elevation transects across Taylor Slough, and higher resolution data for small areas, are being planned for data collection via the AHF. Vertical geodetic control and data collection covering the southwest portions of ENP will also be a new direction

FY 1998 accomplishments and outcomes, including outreach:
The engineering modifications to the AHF and subsequent FAA approval has been a major accomplishment. Testing of the system has shown excellent accuracy and repeatability that well exceeds the 15 cm vertical accuracy specification. A second AHF system is being fabricated for several reasons, and should be completed in FY98. It is planned to use the second system concurrently with the first system when possible to increase data collection rates; to be used as government furnished equipment (GFE) under an Architectural and Engineering (AE) contract; and as a redundant backup in the event of a failure occurring in the primary system. It is anticipated that data collection for the SICS model area will be mostly completed in FY98, though data processing will extend into the beginning of FY99. Also, a quality assessment of contractor delivered data was executed, and showed that with the exception of one file that contained a systematic blunder, the data accuracy was within specification. Efforts to assign required work to our interagency partners and contractors (e.g. geodetic control, additional data collection, datum conversions, etc.) should also be accomplished in FY98.

Outreach activities include a successful South Florida Elevation Data Users Technical Exchange Meeting held at the SFWMD. The focus of the meeting was to brief the User Community on the importance of using NAVD88, and to answer questions regarding data accuracy and future data collection plans. Outreach also included project presentations at a special session of the American Congress on Surveying and Mapping (ACSM) Conference on Surveying and Mapping Activities in Support of the USGS South Florida Ecosystem Program. Additionally, the project was mentioned in an article in National Geographic Magazine, February 1998, entitled ěRevolutions in Mappingî by Pulitzer Prize winning author John Noble Wilford, who accompanied project scientists in the field and conducted interviews.

FY 1998 deliverables, products completed:
The primary deliverable will be high accuracy elevation data for the SICS model area, which encompasses portions of nine 7.5 minute quadrangles.

Key project staff planned to work each fiscal year for the duration of the project:
Vince Caruso- DEM processing
Ed Cyran- AHF engineer and field work project leader, data processing
Greg Desmond- project coordination
Bob Glover- data collection and processing
Chuck Henkle- data collection and processing (contractor)
Gordon Shupe- data collection and processing, quality control

Other required expertise for which no individual has been identified: N/A

Major equipment/facility needs (list by fiscal year for duration of project):
AHE system replacement parts as needed.
Two Ashtech Z-12 geodetic GPS receivers, FY99.
One personal computer system, FY99.
Upgrades and maintenance for data collection and processing equipment, and software.
Helicopter and general aviation facilities for AHF operations as needed.

FY 1999 project budget request: Attach Project Personnel and Operating Expenses Worksheets or BMS staffing sheets.

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