The distributions of nutrients in lakes and reservoirs effect water
quality. Movement of water within these water bodies is the main
mechanism by which nutrient transport occurs. The process of water
movement within a lake or reservoir is a consequence of natural forces.
These forces depend on the effects of rain, wind, solar radiation, surface
cooling, ground water intrusion, photosynthetic activity, gravity, tidal
effects, and the Coriolis force. This study concentrates on the effects of
the diurnal heating and cooling cycle as the primary factor which causes
water movement between the littoral and profundal waters in lakes and
reservoirs. It has been shown that heating and cooling of water on a
littoral slope induces a horizontal temperature gradient and that the density
of water associated with this temperature gradient induces horizontal and
vertical exchange of water along the littoral slope and adjacent profundal
waters (Stefan,Horsch, and Barko, 1989).
The dependence of water movement and consequent nutrient transport
on the water temperature, during the diurnal heating and cooling cycle, is
investigated through analysis of the time dependent temperature profiles
within a shallow heavily vegetated bay and adjacent profundal waters. The
effect of wind on these temperature profiles is also investigated. The data
was collected in a protected bay of a flood detention basin in western
Wisconsin. In this progress report some of the analyzed data is given a
qualitative interpretation. The quantitative analysis, which is currently
being performed, will be the subject of a future report.
This study is based on temperature measurements taken with 38
temperature probes, located at six stations, in the littoral and adjacent
profundal waters of Eau Galle Reservoir at 30 minute intervals during the
period of May 15 to October 13, 1989. Wind speed and direction, air
temperature, solar radiation, and reservoir pool elevation were also
measured. This data is presented in time series plots and the
interrelationship of some parameters is explored. Contour plots of the
spatial distribution of temperatures within the bay transect are also
presented during episodes of heating and cooling, and during a windy period
to illustrate the time and spatial dependence of the water temperatures
during these events.
The data presented in this report were collected by Dr. William F.
James and his auxiliary staff under direction by Dr. John W. Barko. The
data were made available in diskettes, reviewed and plotted by the first
author of this report with guidance provided by the second author. An
earlier report (No. 286) dealt in a very similar fashion with the data
collected in 1988 and has been back labeled Part 1 (1988). This report
deals with data collected in 1989 and is, therefore, labelled Part 2 (1989).
Waterways Experiment Station, Army Corps of Engineers
King, James F.; Stefan, Heinz G..
Heating and Cooling of a Shallow Bay in Eau Galle Reservoir: Field Measurements and Interpretations Part 2 (1989).
St. Anthony Falls Hydraulic Laboratory.
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