|
Project Objectives and Methods Home Project Goals Project Location Study Design Flume Installation Key Personnel Education Contacts |
|
|
Objectives The overall goal of this project is to assess riparian zone vegetation for its sediment, nutrient, and fecal coliform attenuation performance at the watershed scale in southern Illinois agricultural watersheds. Specific objectives include:
Research Strategy Objectives 1 and 2 Southern Illinois University Carbondale (SIUC) owns 2000+ acres of farmland near campus, which is primarily managed as row crop and pasture land. Thus, the property provides an excellent setting for the establishment of long-term riparian buffer research sites, and provides the possibility for future riparian buffer manipulations. The proximity to the University also provides an excellent opportunity to use the property for demonstration and outreach purposes. On SIUC farms, 3 small (<100 ha), row-crop dominated watersheds were selected for long-term water quality and quantity monitoring. At each watershed outlet, a Parshall Flume, a gauging station, and an automatic water sampler will be installed and maintained to monitor long-term stream discharge and water quality. Specific water quality parameters will include nitrate, ammonium, phosphate, total suspended solids, pH, specific conductance, and fecal coliform bacteria. Stream water quality will be measured every two weeks during baseflow periods and during storm events >1.25 cm. Data will be analyzed using a paired watershed approach, where one watershed will be identified as a control watershed and the remaining two watersheds will serve as treatment watersheds. Following equipment installation, all watersheds will be cleared of riparian vegetation, planted with row crops to the stream margin, and then calibrated for a 3 year period based on discharge and water quality relationships among the watersheds. During the calibration period, any volunteer woody species that become established in the riparian areas will be removed. Following the calibration period, one treatment watershed will be planted with a 10 m wide giant cane buffer along both sides of the stream and the other treatment watershed’s riparian zone will be planted with a 10 m wide mixed hardwood buffer on both sides of the stream, including, green ash (Fraxinus pennsylvanica Marsh.), white oak (Quercus abla L.), and pin oak (Quercus palustris Muenchh.). The control watershed will continue to have row crops planted up to the stream edge and any volunteer woody species will be removed throughout the duration of the study. Objective 3 Channel morphometry measurements will be recorded within each watershed using fixed cross-sectional depth transects that will be re-measured at regular intervals. Measurements will be confined to straight channel reaches in run habitats to avoid overestimates of channel scour. A detailed grid analysis will also performed in each watershed. Three fixed grids will be established in straight reaches and be confined to runs in each stream. Each grid will consist of 5 transects perpendicular to the channel and will be measured at 0.5 m intervals. Following storm events (>1.25 cm of precipitation) each grid will be resurveyed to determine scour and fill volumes. Benchmark elevations will be established and measured each sampling period to account for changes due to equipment movement. Streambed substrate classification will be performed for each stream using dry-sieving techniques where size classes will be characterized according to USDA guidelines (Soil Survey Division Staff 1993). Three sediment cores will be randomly located within the grid sections to allow comparison of distributions of coarse and fine materials within the stream channels to assess the relationship with fill and scour of the stream beds (Leopold et al. 1995). Objective 4 A plot-scale experiment will be designed to test the binding potential of fecal coliform bacteria by common riparian buffer vegetation species and their associated soils. Twelve 1x10m plots will be created in established riparian zones planted with grass, giant cane, and mixed-hardwood species (i.e., 3 replicates of each vegetation, and 1 corresponding control plot). A retaining material that impedes water will be installed to delineate plot boundaries and will allow the vegetative plots to be subjected to a controlled volume of FC-laden overland flow. A solution of a water and cattle waste will be mixed in a 400 gallon water tank, which will be applied to the upper end of the plots. Input and output concentrations of fecal coliform will be assessed for each plot, and concentrations will be assessed at 2 meter intervals throughout the plot length. Samples will be collected at 2 minute intervals until the entire 400 gallon solution is applied. Within each riparian vegetation cover type, 3 experimental plots and a control plot will be installed. The control plots will be cleared of all vegetation and litter, which will help account for soil variability and attenuation potential for each site. Within each plot, soil characteristics (e.g., bulk density, particle size, and infiltration rates) will also be assessed to determine the effect that soil physical characteristics have on fecal coliform attenuation. References: Leopold, L.B., M.G. Wolman, and J.P. Miller. 1995. Fluvial Processes in Geomorphology. Dover Publications, Inc. New York. 522pp. Soil Survey Division Staff. 1993. Soil Survey Manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18.
|