Robert W. Ritzi, Jr., Ph.D. (Committee Chair); David A. Schmidt, Ph.D. (Committee Member); David F. Dominic, Ph.D. (Committee Member)
Master of Science (MS)
The Theis Environmental Monitoring and Modeling Site is a field research facility, located on the Great Miami River in southwest Ohio, dedicated to the study of hyporheic zone processes. The site is underlain by an aquifer on the order of 21 meters thick, comprised of fluvial deposits. The permeability of the aquifer sediments was quantified both from one large scale hydraulic test (~100 m radial distance) and from grain-size analysis of 119 small-scale core samples (~20 cm length each). The permeability determined from the large-scale hydraulic test is 98.9 Darcies. The test also gave a value for specific yield of 0.25. The geometric mean of the small-scale measurements is 88.3 Darcies, close to the value of the large-scale measurement, and within the central tendency of the distribution of previously published measurements. The aquifer contains an inferred hierarchy of sedimentary architecture, with compound bar deposits comprising unit bar deposits, and unit bar deposits comprising stratasets with different grain-size facies, including sand, gravelly sand, sandy gravel, and gravel. The stratasets are less than a meter thick and less than 10 meters in length. Intervals of sand facies make up 18.5% of the aquifer, have a mean thickness of 0.75 m (standard deviation (σ) of 0.37 m), a mean permeability of 86.8 Darcies (σ of 47.8 Darcies), and a mean porosity of 36% (σ of 4%). Intervals of gravelly sand facies make up 25.2% of the aquifer, have a mean thickness of 0.96 m (σ of 0.46 m), and a mean permeability of 73 Darcies (σ of 49.9 Darcies), and a mean porosity of 28% (σ of 3%). Intervals of sandy gravel facies make up 36.1% of the aquifer, have a mean thickness of 1.00 m (σ of 0.79 m), and a mean permeability of 84.9 Darcies (σ of 49.7 Darcies), and a mean porosity of 25% (σ of 3%). Intervals of gravel facies make up 20.2% of the aquifer, have a mean thickness of 1.10 m (σ of 0.74 m), and a mean permeability of 670 Darcies (σ of 1170 Darcies), and a mean porosity of 25% (σ of 4%). Gravel intervals are inferred to be lag deposits at the base of compound bars. There are stacked vertical sequences of three to five inferred compound bar deposits within the aquifer. The mean thickness of inferred compound bar deposits is 6.15 m (σ of 5.06 m) and their inferred lateral extent is of the order of 500 m to kilometers. Fining-upward sequences within the compound bar deposits are inferred to be unit bar deposits, in stacked vertical sequences of one to six unit bar deposits per compound bar. The unit bar deposits have a mean thickness of 2.40 m (σ of 0.94 m) and an inferred lateral extent of the order of 10 to 100 m. The mean permeabilities of the sand, gravelly sand, and sandy gravel facies are not statistically significantly different, however the mean permeability of the gravel facies is statistically different from the other three facies. Therefore, the aquifer could be parsimoniously characterized by two permeability facies: a moderate permeability facies that includes the sand ,gravelly sand, and sandy gravel sedimentary facies (k = 81.6 Darcies, σ = 48.9) and a high permeability facies that includes the gravel sedimentary facies (k = 670 Darcies, σ = 1170).
Department or Program
Department of Earth and Environmental Sciences
Year Degree Awarded
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