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Vegetative Resistance to Flow in the Everglades

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Frequently-anticipated questions:

What does this data set describe?

Title: Vegetative Resistance to Flow in the Everglades
Abstract:
Surface-water flow models are needed to evaluate restoration and management alternatives for the south Florida ecosystem. Model results are sensitive to expressions used to represent flow resistance due to vegetation. The project seeks to develop methods for representing flow resistance due to vegetation types typically found in the Everglades. The project also seeks an understanding of the effect of vegetation on surface-water flow and improved techniques for measuring flow velocities and water-surface slopes in wetlands.
  1. How should this data set be cited?

    Harry Jenter Raymond Schaffran, Virginia Cater (retired), Jonathan K. Le, 1999-2003, Vegetative Resistance to Flow in the Everglades.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -81.201351
    East_Bounding_Coordinate: -79.141576
    North_Bounding_Coordinate: 27.141576
    South_Bounding_Coordinate: 24.838753

  3. What does it look like?

    <http://sofia.usgs.gov/exchange/carter/sitesflume.html> (GIF)
    locations of data collection sites

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: Oct-1994
    Ending_Date: Sep-2002
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Project personnel include Michael Duff, Nancy Rybicki, Al Lombana, Lisa Roig, and Vincent Lai.

  3. To whom should users address questions about the data?

    Harry Jenter
    U.S. Geological Survey
    430 National Center
    Reston, VA 20192
    USA

    703 648-5916 (voice)
    703 648-5484 (FAX)
    hjenter@usgs.gov

Why was the data set created?

Data fundamental to quantifying the effects that the highly variable vegetation of the Everglades has on shallow surface-water flows is lacking. Models presently being used to manage the ecosystem need to quantify the flow-resistance effects of vegetation in order to properly simulate flow. These management models have been forced to rely primarily on qualitative estimates and engineering judgments for the treatment and representation of vegetative flow resistance. The objectives of this project are: 1) to collect data to produce accurate values of flow-resistance coefficients for use in numerical simulation models, 2) to analyze these flow data to quantify the resistance effects of the submerged vegetation, 3) to investigate the vegetation/flow-resistance correlation in controlled laboratory experiments and in the field, 4) to isolate the key vegetation properties to which the evaluation of resistance effects can best be correlated, and 5) to derive expressions that can be used to more creditably represent these effects in numerical models. These findings can be used to establish the validity of management models presently in use throughout the entire Everglades ecosystem as well as to provide improved expressions for representing the resistance effects of vegetation on flow for incorporation in newly developed models.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 1998 (process 1 of 2)
    Velocity-profile and vegetation data collected in the flume in FY 1996 and FY 1997 were analyzed. Water-surface-elevation and pipe-flow data collected in the flume in FY 1996 were analyzed and used to calibrate a unique pipe manometer used to obtain water-surface slopes in wetlands. A 2.4-meter-long, 7.6-centimeter-diameter plastic pipe with a short elbow at one end is positioned horizontally just below the water surface and parallel to the flow direction with the elbow at the upstream end and pointing down. The velocity of water in the pipe is a function of the characteristics of the pipe and the difference in water-surface elevation at the entrance and exit. The centerline flow velocity in the pipe is measured by inserting an ADV that is equipped with a side-looking probe into the downstream end of the pipe. The pipe was calibrated in the flume at the hydraulics laboratory at Stennis Space Center and has proven to be an efficient, accurate method for the local measurement of water-surface slopes for the low-velocity, small-gradient flows of the Everglades.

    Velocity-profile and vegetation data collected in the field in FY 1996 and FY 1997 at sites P33 and NESRS3 in the Everglades National Park were analyzed. Pipe-flow data collected at these sites in FY 1997 were analyzed, and water-surface slopes were obtained from the pipe-flow data. Field measurements were made in November 1997 in the Taylor Slough basin in the Everglades National Park to obtain information on the relation between flow and vegetation characteristics. Measurement of flow depth, flow velocity, and water-surface slope was necessary to evaluate flow resistance. Vegetation was sampled wherever hydraulic measurements were made. Approximately 20 hydraulic and 20 vegetation measurements were made during this field trip. An ADV was used to measure flow velocities, and the pipe manometer was used to obtain water-surface slopes.

    Date: 2000 (process 2 of 2)
    Data collected in the USGS tilting flume at the Stennis Space Center, MS, were used to determine the flow resistance of uniform stands of sawgrass. Experiments were conducted for five flow depths between 0.15 and 0.76 meters, for mean cross-sectional velocities between 0.15 and 5 cm/s, and for three plant densities. Hydraulic measurements of the water-surface slope and flow velocities were made during each experiment using modified hook gages and acoustic Doppler velocity (ADV) meters. The vegetation in the flume was sampled and characterized during each experimental series (Rybicki, et. al., 1999), each consisting of 20 to 40 experiments. The vegetation in the flume was sampled to determine, as a function of depth, the biomass per unit area, number of stems and leaves per unit area, leaf and stem widths, as well as other characteristics. Concurrent flow and vegetation data were also collected at numerous sites in Shark Valley Slough, Taylor Slough, WCA-2, and the ENR area for various types of plant communities including sawgrass, rush, cattail, and others, to supplement the laboratory experiments.

    In order to collect the data needed to evaluate and develop flow-resistance expressions, a unique pipe-manometer method was devised to determine the local water-surface slope in wetlands. The device is a 2.4-meter-long plastic pipe, 7.6 cm in diameter, with a 90-degree elbow at one end. The pipe was positioned in the water column parallel to the flow direction and an ADV meter equipped with a side-looking probe was used to measure the centerline flow velocity in the pipe. Knowing the flow characteristics of the pipe, the difference in the water-surface elevation at the ends of the pipe is calculated from appropriate expressions using the measured centerline flow velocity in the pipe. The pipe manometer is currently calibrated, and appears to hold great potential as an efficient, accurate method for the local measurement of the shallow water-surface slopes typical of the low-velocity, small-gradient flows in the Everglades.

    The death of Dr. Jonathan Lee, the project chief, in December of 1999 prompted the need for development of new approaches to accomplish the project objectives. All project laboratory and field datasets collected over the four-year duration of the project (1996-1999) were organized and catalogued by project personnel during December of 1999 and January of 2000 and have been analyzed throughout the remainder of the year to yield velocity profiles, depth-averaged velocities and Manning’s n values. Data from the laboratory, Shark Slough, Taylor Slough and Water Conservation Area 2A have been analyzed and tabulated. Summary reports describing these data sets were prepared.

    In the spring of 2000, contracts were initiated with Dr. Vincent Lai to complete the pipe manometer theoretical analysis and calibration and Dr. Lisa Roig to complete the vegetative resistance calculations for both laboratory and field data.

    All data pertaining to the calibration of the pipe manometer were processed during January and February of 2000. The data were turned over to Lai for evaluation in March 2000. In turn, Lai has provided the Project Chiefs with a draft report describing the theory of the pipe manometer, including definition of the limits of laminar, transitional and turbulent flow theory.

    At the end of March, Roig initiated a literature review on the subject of vegetative resistance to flow using Lee’s files and notes as one source of reference information. This review is completed and serves as a precursor to her analysis of Lee’s laboratory and field data. It also serves as a valuable reference resource for others contributing to this project.

    Major scientific outcomes for this project during FY 2000 included:

    1. The theoretical limits of applicability of Lee’s pipe manometer method for computing water-surface slopes have been determined and defined. This allows other researchers to identify situations in which the pipe manometer technique can be used to accurately measure the local water-surface slope.

    2. The pipe manometer calibration data show a distinct, nearly-linear variation between the pipe centerline velocity and the square root of the water surface slope. For the pipe manometer geometry used on this project in both the field and laboratory, this implies that the developed calibration is applicable throughout the range of velocities typically observed in the Everglades (Calibration data collected in the laboratory span the range 0.3 cm/s - 7.5 cm/s).

    Person who carried out this activity:

    Harry Jenter
    U.S. Geological Survey
    430 National Center
    Reston, VA 20192
    USA

    703 648-5916 (voice)
    703 648-5484 (FAX)
    hjenter@usgs.gov

  3. What similar or related data should the user be aware of?

    Carter, Virginia Rybicki, Nancy B.; Reel, Justin, 199907, Classification of Vegetation for Surface-Water Flow Models in Taylor Slough, Everglades National Park: Third International Symposium on Ecohydraulics Proceedings, International Association for Hydraulic Research Association for Hydraulic Research (IAHR), Salt Lake City, UT.

    Online Links:

    Carter, Virginia Ruhl, Henry A.; Rybicki, Nancy , 1999, Vegetative Resistance to Flow in South Florida: Summary of Vegetation Sampling at Sites NESRS3 and P33, Shark River Slough, April, 1996: USGS Open File Report 99-187, U.S. Geological Survey, Reston, VA.

    Online Links:

    Carter, Virginia Reel, Justin T.; Rybicki, Nancy, 1999, Vegetative Resistance to Flow in South Florida: Summary of Vegetation Sampling ar Sites NESRS3 and P33, Shark River Slough, November, 1996: USGS Open File Report 99-218, U.S. Geological Survey, Reston, VA.

    Online Links:

    Rybicki, N. B. Reel, J.; Ruhl, H. A.; Gamm, 1999, Biomass and Vegetative Characteristics of Sawgrass Grown in a Tilting Flume as Part of a Study of Vegetative Resistance to Flow: USGS Open File Report 99-230, U.S. Geological Survey, Reston, VA.

    Online Links:

    Rybicki, Nancy B. Reel, Justin T.; Ruhl, Henr, 2001, Vegetative Resistance to Flow: Summary of Vegetation Sampling in Taylor Slough, Everglades National Park, September 1997-July 1998: USGS Open-File Report 01-102, U.S. Geological Survey, Reston, VA.

    Online Links:

    Rybicki, Nancy B. Reel, Justin T.; Ruhl, Henr, 2000, Sawgrass density, biomass, and leaf area index: a flume study in support of research in wind sheltering effects in the Florida Everglades: USGS Open File Report 00-172, U.S. Geological Survey, Reston, VA.

    Online Links:

    Lee, J. K. Visser, H. M.; Jenter, H. L, 2000, Velocity and Stage Data Collected in a Laboratory Flume for Water Surface Slope Determination Using a Pipe Manometer: USGS Open-File Report 00-393, U. S. Geological Survey, Reston, VA.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    not available

  5. How consistent are the relationships among the observations, including topology?

    not applicable

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none
Use_Constraints: none

  1. Who distributes the data set? (Distributor 1 of 1)

    Heather S.Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  2. What's the catalog number I need to order this data set?

    Vegetative Resistamce to Flow in the Everglades

  3. What legal disclaimers am I supposed to read?

    No warrantees are implied or explicit for the data

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2007
Metadata author:
Heather Henkel
U.S. Geological Survey
600 Fourth Street South
St. Petersburg, FL 33701
USA

727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
sofia-metadata@usgs.gov

Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <http://sofia.usgs.gov/metadata/sflwww/veg_resist_flow_mod.faq.html>

U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology
Comments and suggestions? Contact: Heather Henkel - Webmaster
Generated by mp version 2.8.18 on Tue Mar 20 09:49:03 2007