OVERVIEW

This quarterly report discusses tasks undertaken and progress made on the USU REMAP project during the period October 1 to December 31, 1999. The primary task on the project during this period was reduction and analysis of field data. Additionally, two project presentations were made during this quarter. These two items are discussed in detail below.

DATA REDUCTION AND ANALYSIS

The primary task during the quarter was the reduction and analysis of field data collected from the eight study watersheds located in Utah. Field data were generally collected onto paper forms, with this information input into computerized data files for analysis and presentation. Previous quarterly reports provide additional information on the sampling strategy, types of data collected, and data collection methods. This quarterly report provides a summarized view of some of these data. Data analysis is ongoing.

Vegetation Cover Data

Several types of vegetation cover information were collected at between 45 and 60 sample sites in each watershed. Vegetation cover type frequency was collected using the "point intercept on a transect method," with a total of 100 points sampled along the tape at l-foot intervals. (For more information on this data collection method, see the quarter 4 report.) At each of the 100 points along the tape, plant species was recorded, if species identification was possible. Otherwise, genus, family, or life form was recorded depending upon the amount of specimen available. Other non-vegetation or non-living vegetation categories included litter (fallen vegetation), rock (greater than 1.27 centimeter or 1/2; inch), pebble (less than 1.27 cm or 1/2; inch), and bare soil. Among the eight watersheds, there were a total of 385 cover sample sites, which yielded 38,500 sample points. A total of 172 cover types were identified amongst the eight watersheds.

Aggregation of all sample site data from a watershed provides an overall characterization of a watershed's vegetation cover. Figure 1 presents a comparison of cover data for the eight watersheds and illustrates the diversity in cover. For example, the amount of bare ground, pebble, and rock cover (gray slices in Figure 1) is greater for the more arid Beaver River and Otter Creek watersheds than for the watersheds in northern Utah. Cover and other vegetation data are being analyzed using spatial and non-spatial statistical methods, being used as a basis for interpreting aerial imagery, and will be used in the modeling components of the investigation.

Figure 1.  Comparison of cover type frequency for the eight Utah REMAP watersheds. Note that the individual pie slice colors do not necessarily represent the same cover type. Click on a pie to see a detailed graphic with cover type labels and cover percentages. [Watershed location map]

Infiltration Data

Small-cylinder infiltration tests were made at 18 to 24 of the vegetation sample sites in each of the watersheds. (Infiltration test methods were presented in the quarter 4 report.) Three tests were made at each site, one each at 10-, 20-, and 30-meter distances along the vegetation transect tape, yielding a total of 468 infiltration tests made in the eight watersheds. Raw data from the infiltration tests were fit to Green and Ampt and Philips infiltration equations to provide soil parameters of sorptivity, hydraulic conductivity, initial infiltration rate, and final infiltration rate. Figure 2 illustrates an example of input data and calculated parameter output for one site.

Figure 2.  Example of data output from soil hydraulic property calculations.

Soil Data

Various soil parameter information (described in the quarter 4 report) was collected at the same 468 site at which infiltration tests were conducted. One soil parameter being evaluated is soil bulk density, defined as soil mass per volume. Bulk density is primarily a function of mineral density (usually about 2.65 g/cm³), porosity, and organic content, with porosity and organic content related to cover, land use, depth, and other factors. Bulk density samples were collected at 0-5 cm and 5-10 cm depths at each of the three infiltration test locations at each sample site.

Figure 3 illustrates several relationships between bulk density variation and spatially distinct areas in the Otter Creek Watershed No. 1. As expected, the 0-5 cm depth samples have lower bulk densities than the 0-10 cm depth samples, indicating higher porosity and greater organic content for the shallower soil depths. Statistically significant differences in bulk densities are noted in this watershed for OFE clusters, soil types, and slope azimuth (Figure 3a, b, and c).

Figure 3. Bulk density relationships in Otter Creek Watershed No. 1. Average bulk density for a) each OFE in the watershed, b) each of the 4 OFE Clusters, c) four watershed soil types, and d) north-facing versus south-facing slopes.

PRESENTATIONS

Two project presentations were made during the quarter. On October 26^th, Craig Goodwin (Research Associate) made a presentation at the Annual meeting of the Geological Society of America (GSA) in Denver, Colorado. The presentation was made in the session Geomorphic and Ecological Responses to Natural and Anthropogenic Disturbances sponsored by the GSA's Quaternary Geology and Geomorphology Division. The abstract of the talk is available for viewing at the GSA web site. The slide show that was presented can be viewed at the USU REMAP web site.

On December 15^th, G. Allen Rasmussen (Project Manager), James Dobrowolski (Project Investigator), and Craig Goodwin (Research Associate) made a presentation for the EMAP/REMAP staff at EPA's Region 8 office in Denver, Colorado. The presentation provided an overview of the project, including goals, status, and possible future directions. The presentation is available on line at the USU REMAP web site.