Valdosta State University Students (1993-1999)
|While at Valdosta State University I was fortunate
to have worked with several talented undergraduate students on a variety
of research projects including rill erosion, lacustrine
sedimentology, sinkhole development,
and digital elevation modeling. I have thoroughly
enjoyed working with Jay, Nancy, Holly, Buck, Brent, and Jeff on these
projects. Although I am very proud of the research that each has done,
I should mention that both Jay Winkler and Holly Wilkes received
outstanding paper in geography awards for their presentations
at the Georgia Academy of Sciences meetings in 1996 and 1998 respectively.
Abstracts given below are taken either from the student's final report,
or from published abstracts in the Georgia Journal of Science.
Twelve of 17 pre-existing rills at Plot 1 were lengthened by headward erosion increasing the total length of rills by 16 m (9% of the total rill length for plot 1). This lengthening occurred nearly equally downslope from vegetated and non-vegetated areas, and was in part controlled by a hard silty-clay layer at 15 to 20 cm depth (mean bulk density = 1.75 g/cm3). This layer inhibited vertical erosion and promoted sapping and headward erosion. Results from plots 2 and 3 show that most new rills form during the first rainstorm. Based on estimates of elevation change, nearly 4 times more erosion occurred at plot 2 (no vegetation upslope) than at plot 3. However, much of this difference was due to the deposition of an coluvial fan at plot 3. These findings imply that erosion on embankments will be minimized if vegetation is established quickly following completion of embankment construction (i.e. before the first major rainfall). Even small amounts of protective vegetation will greatly reduce the development of rills.
Reference: Winlker, J. L., and Hyatt, J. A. 1996. Georgia Journal of Science, Vol 54, p. 49.
Near-surface sediments within Lake Louise, Georgia, form
a 15 to 20 cm thick layer of light gray sediment that is enriched relative
to underlying sediment in inorganics (by a factor of 2.5) and trace metals
(e.g. Ti by 28, Ba by 3, Pb by 36). This enrichment has previously been
attributed to the influx of clastic sediments to the lake during construction
of near-by interstate 75 in 1957. In this study we examine the spatial
variability of inorganic sediment within this surface layer (SL). Our purposes
are: (1) to infer controls on sedimentation, (2) to estimate how much sediment
and metal has entered the lake because of highway construction, and (3)
to discuss implications of observed spatial trends to trace metal loading
in the lake. Sixteen Eckman grab samples of the SL were recovered at 10
m intervals across the lake. Volumetric subsamples from the top, middle,
and bottom of the SL were analyzed to determine moisture content, dry bulk
density, and inorganic content (by LOI). The middle (M) and top (T) sample
groups are statistically indistinguishable from one another. However, the
bottom sample group (B) has significantly higher inorganic sediment content,
dry bulk density, and lower moisture content than the combined M-T sample
group. In addition, simple linear regression indicates a statistically
significant trend (r2=0.54, p<0.001) of increasing inorganic
content with increasing water depth. This trend is strongest for B samples
and likely reflects an initial focusing of construction-derived clastic
sediment into the deepest parts of the lake by turbidity flows. Subsequent
bioturbation and a diminished post-construction influx of sediment to the
lake may be responsible for the reduced focussing trend apparent in the
M-T sample group. Using these trends together with bathymetric data we
estimate between 7.1 and 10.1 x 105kg of dry sediment and
significant quantities of trace metals (e.g. 6540 kg Ti, 270 kb Ba, 60
kg Pb) were introduced to the lake by highway construction. In addition,
sequential extractions performed on SL sediments indicate that the majority
of trace metals reside within the inorganic sediment fraction. Consequently,
the observed focussing of inorganic sediment to the deep parts of the lake
basin implies a similar concentration in trace-metals within Lake Louise.
Reference: Bearden, A. B., and Hyatt, J. A. 1998. Georgia Journal of Science, Vol 56, p. 54.
Reference: Wilkes, H. P., and Hyatt, J. A. 1998. Georgia Journal of Science, Vol 56, p. 54.
Water color and change in water volume for Lake Louise are of particular interest because they give insight to past changes in regional hydrology. Previous studies of lake core suggest that water levels were higher, lake volume was greater, and water color was less dark prior to 4000 years before present than it is today. This study tests this hypothesis by (1) analyzing the color of water in lake-side swamps and in the open lake, and by (2) constructing digital elevation models (DEM) to determine changes in the volume of swamp and open lake for various water levels. Color data indicate that swamp water is more than twice as dark as lake water. Data also show an increase in water color with an increase in water depth. Little difference is noted between open water in the center of the lake and open water around the lake margin that has abundant algae. DEM data show that as water levels rise the ratio of swamp volume to open lake volume increases. These data also reveal a critical water level that joins together the Lake Louise and Browns Pond drainage basins. At this critical water level, swamp volume increased by a factor of 80.
Color and volumetric data suggest either that previously higher water levels were not substantially lighter in color than present, as presumed, or that factors other than just the size of the swamp should be considered when inferring paleohydrology for the site.
Reference: Collier, B. A., 1998. Final Report, GLY 499, 17 pp.