Raymond Schaffranek (retired); Virginia Cater (retired); Jonathan K. Lee (deceased)
Reel, J.; Ruhl, H. A.; Gammon, P. T.; Carter, V.; Lee, J. K.
U.S. Department of Agriculture - Natural Resources Conservation Service (NRCS) Department of the Interior - U.S. Geological Survey Department of Commerce - National Oceanic and Atmospheric Administration (NOAA) Environmental Protection Agency (EPA) Smithsonian Institution - National Museum of Natural History (NMNH)
Rybicki, Nancy B.; Reel, Justin T.; Ruhl, Henry A.; Stewart, David W.; Jones, John W.
Reel, Justin T.; Rybicki, Nancy B.; Ruhl, Henry A.; Gammon, Patricia T.; Lee, Jonathan K.
Reel, Justin T.; Ruhl, Henry A.; Gammon, Patricia T.; Carter, Virginia
Reel, Justin T.; Ruhl, Henry A.; Gammon, Patricia T.; Carter, Virginia; Lee, Jonathan K.
Visser, H. M.; Jenter, H. L.; Duff, M. P.
Reel, Justin T.; Rybicki, Nancy B.; Ruhl, Henry A.; Gammon, Patricia T.; Lee, Jonathan K.
It was necessary to trim the tops of the sawgrass back to 1 meter total height frequently to permit the measuring cart to move across the top of the flume. For this reason, the >90 cm layer was not measured after September, 1995, until June 1997, when the tops of the plants were allowed to grow for wind simulation experiments. Visually, the plants were generally healthy and green with strongly stiff and upright leaves (the tips having been cut off). Some mortality occurred as time went on and new plants also sprouted. During some periods between sampling, plants were thinned out or transplanted to fill gaps. The amount of litter in the bottom increased naturally, but was far less than observed in the field. For this reason, the bottom litter was added to by throwing the cut-off tops of the plants into the flume in order to more closely simulate the natural field conditions.
Plant descriptions: For the descriptive information, all leaves and culms in each layer were counted and dried. Leaves were separated into small, medium, and large classes and 6 widths for each size class measured (when possible). Likewise, culms were divided into small and large classes and 6 diameters measured for each class. In October 1996, March 1997, and June 1997, additional descriptive information was collected including number of live culms, number of dead standing culms, number of live leaves, number of dead standing leaves, and, in June, 1997, composition of the vegetation above 90 cm.
Leaf area index (LAI) in m2 m-2 was calculated for each layer using the equation:
LAI = (LL x AW for the LL + ML x AW for the ML + SL x AW for the SL+ LC x AW for the LC + SC x AW for the SC) x DL,
where LL = number of large live plus dead leaves, AW = average width of live leaves or culms, ML = number of medium live plus dead leaves, SL = number of small live plus dead leaves, LC = number of large live plus dead culms, SC = number of small live plus dead culms, and DL = depth of the layer in meters. LAI includes only standing plant material; however, dead litter accumulates in the flume over time, and this also provides resistance to flow. To account for the resistance of the dead litter, the ratio of dead litter biomass to standing plant biomass was calculated, the LAI was multiplied by this ratio, and the result was added to the LAI to provide a corrected LAI.
For procedures used at each sampling date and treatment between and during sampling data, see OFR 99-230.
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.
During each experimental wind series, the vegetation in the flume was sampled to determine biomass per unit area, the number of live and dead standing culms and leaves per unit area, and leaf and culm width as a function of distance from the bed or the sediment/water interface. Other characteristics of the vegetation were also measured during these experiments. The general methods for measuring biomass and plant characteristics are outlined below. Measurements were made in June, 1997, October, 1997, April, 1998, and July, 1998. Measurement dates, type of measurements, condition of plants, and activity between measurements are summarized in the report.
Quadrat Biomass Measurements Sawgrass biomass was measured in 37x55 cm quadrats; eight to twelve quadrats were characterized on each date. In June, 1997, three quadrats were randomly selected from each quarter of the entire flume. Six of these (1A-C and 2A-C) were located in the area where the wind cowling would be placed. After June, 1997, the wind cowling was constructed, and the flume beneath the wind cowling was divided into an upstream (1) and a downstream (2) half. Four quadrats (A-D) were randomly selected in each half. For each quadrat and on all sample dates, leaves, culms, and dead material were cut and removed in 20-cm layers between 0 and 60 cm from the sediment/water interface and at 30-cm layers above 60 cm, starting at the top. The plant material from each layer was sorted (see plant descriptions below), dried at 105 °C for about 12 hours, and weighed, with weight expressed as grams dry weight per square meter (gdw/m2). All vegetative components, live leaves, live culms, dead standing leaves, dead standing culms, and dead litter were separated, and their biomass was measured separately. Biomass data for individual quadrats were averaged to give layer-by-layer biomass data for the flume for each date.
Plant Descriptions For each quadrat and on all sample dates, all leaves and culms in each layer were counted. Live leaves and dead leaves were separated into small, medium, and large classes; six widths were measured for each live size class (when possible). Likewise, live and dead standing culms were divided into small and large classes, and six live diameters were measured for each class, except in April, 1998, and July, 1998, when no widths were obtained for dead culms. Descriptive data were summarized for each date. Leaf area index (LAI) in m2 m-2 was calculated for each layer using the equation:
LAI = (LL x AW for the LL + ML x AW for the ML + SL x AW for the SL+ LC x AW for the LC + SC x AW for the SC) x DL,
where LL = number of large live plus dead leaves, AW = average width of live leaves or culms, ML = number of medium live plus dead leaves, SL = number of small live plus dead leaves, LC = number of large live plus dead culms, SC = number of small live plus dead culms, and DL = depth of the layer in meters. LAI includes only standing plant material; however, dead litter accumulates in the flume over time, and this also provides resistance to flow. To account for the resistance of the dead litter, the ratio of dead litter biomass to standing plant biomass was calculated, the LAI was multiplied by this ratio, and the result was added to the LAI to provide a corrected LAI.
For procedures used at each sampling date and treatment between and during sampling data, see OFR 00-172.
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).
Table 2 contains selected results of flume vegetation sampling for six months. Parameters are Average total biomass, Class (medium sawgrass), Total number of leaves at 40-60 cm, Total number of leaves at 20-40 cm, Total number of culms at 0-20 cm, Total number of culms at 20-40 cm, and Total dead biomass at 9 months, 13 months, 17 months, 21 months, 27 months, and 30 months.
Table 3 shows the summary of uncorrected Leaf Area Indices (LAI) for six plant ages (9 months, 13 months, 17 months, 21 months, 27 months, and 30 months) for 60-90 cm, 40-60 cm, 24-40 cm, 0-20 cm and total.
Table 4 shows data for the sawgrass biomass in the flume for September, 1995 (9 months)
Table 5 shows data for the sawgrass biomass in the flume for January, 1996 (13 months)
Table 6 shows data for the sawgrass biomass in the flume for May, 1996 (17 months)
Table 7 shows data for the sawgrass biomass in the flume for October, 1996 (21 months)
Table 8 shows data for the sawgrass biomass in the flume for March, 1997 (27 months)
Table 9 shows data for the sawgrass biomass in the flume for June, 1997 (30 months)
U.S. Department of the Interior, U.S. Geological Survey
Comments and suggestions? Contact: Heather
Henkel - Webmaster
Generated by mp version 2.8.18 on Wed Mar 04 14:34:40 2009