Thesis (Ph. D.)--University of Michigan, 1933.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [189]-196).

A glacierized 24 km² watershed in the Coast Mountains of British Columbia was studied during the 1976 melt season in order to investigate the naturally occurring spatial and temporal variations of stream water chemistry. The chemical species measured were those that have been shown to be the major products of chemical weathering: calcium, magnesium, potassium, sodium, and silica. Detailed analysis of errors in field and laboratory procedures were an integral part of the research design and it was shown that errors on individual determinations were similar to those of university and government laboratories. The two major components of the research design were: 1) comparison of the chemistry of four major tributaries within the study area, and 2) an analysis of the temporal variability of stream chemistry at the basin outlet. The results of paired comparisons of tributary chemistry were consistent with geologic differences between sub-basins. For example, potassium concentration was greater in streams draining granodiorite than in a stream draining only quartz diorite, reflecting the lesser abundance of K-feldspar in quartz diorite. The highest solute concentrations were observed in spring water draining a metamorphic roof pendant while glacier meltwater had the lowest concentrations of all terrestrial water. Four models were investigated for describing the relationship between stream chemistry and stream discharge at the basin outlet. The best predictive model for calcium concentration (log Ca = a + b log Q, Ca = 10[sup a] Q[sup b]) explained 60% of the calcium variance. However, subsequent analysis showed that the unexplained variance contained information about temporal changes in runoff sources. In particular, the time-dependent behavior of the residual variance was interpreted as the result of an increase in the ratio of glacier meltwater to ground water discharge through the summer. Furthermore, the sub-basin approach in the research design made it possible to objectively identify the two glacierized sub-basins as the source of this phenomenon. All solutes behaved similarly except potassium which generally varied little through time or with changing discharge. This was attributed to the high availability of K⁺ in vegetation and soils and an apparent buffering of its concentration in the weathering zone. In a glacierized sub-basin almost lacking well-developed soils and forested slopes, potassium behaved more like the other solutes. All terrestrial water was shown to be in equilibrium with kaolinite in the Ca-plagioclase weathering system. Within the kaolinite stability field, water samples from different sources plotted in positions that were consistent with the availability of plagioclase, residence time, and the availability of C0₂ as a source of acidity during hydrolysis. / Arts, Faculty of / Geography, Department of / Graduate

Polarization plays a significant role in the physical and chemical properties of water, thus polarizable water models have been extensively evolved and studied in the past several decades. In this dissertation, two polarizable water models have been extended, and some physical properties in gas phase and condensed phase were studied and analyzed. It was verified that the out-of-plane polarization effect is of great importance in some physical properties. Besides, we proved that there are some connections between these two models, although they were derived from different methodologies. The first polarizable water model we developed was a combination of charge response kernel (CRK) method and polarizable point dipole (PPD) method. In the CRK method, a CRK matrix is defined as the second order derivative of energy with respect to the external potential at atomic sites. It is applied to represent the intensity of charge response to external environment. While in the PPD method, the polarizability tensor which is the second order derivative of energy with respect to external field at the same site, is introduced to characterize the variation of dipole moment in the presence of external perturbation. In our method, we proved that although the CRK matrix of three-site water model has 9 element, it only carries two independent variables, and these two variables only rely on the water geometry and the in-plane polarizability. Thus besides the CRK matrix located on each atomic site, an additional polarizability residing on oxygen atom specifically inducing dipole moment along the direction perpendicular to the water plane was added in our model. With the addition of the out-of-plane description, some physical properties were much enhanced. In the second polarizable water model we extended, electronegativity equalization (EE) method was employed. In this three-site water model, atomic electronegativity and hardness matrix were the first and second order derivative of energy with respect to the partial charge on atomic sites, respectively. In this method, electronegativity differs among different atom types, and the off-diagonal elements in hardness matrix are related on not only atom types but also distances among the corresponding atoms. Accordingly, the intramolecular water deformation can be included. Thus flexible polarizable water model is accessible. With flexibility, this water model is more realistic. Our model validated that more flexible parameterization and geometry could improve the physical performance. At last, we connected the second polarizable water model with the first one. Although the two polarizable models were derived from different methodologies, we proved that under one simple approximation, corresponding CRK matrix can be achieved from hardness matrix. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

This thesis presents studies of the heterogeneous nature of groundwater-surface water (GW-SW) interactions at the hillslope and catchment scale in the 3.2km2 Bruntland Burn, UK. GW fluctuations were measured within three contrasting hydropedological units. Synoptic hydrogeochemical surveys were carried out (major ions, stable isotopes) to capture the increased influence of GW to the stream during a 10year return period drought. The catchment was shown to have highly dynamic GW stores, with each landscape unit translating into different rainfall-runoff processes. Soil characteristics were shown to be the strongest predictors for variability in GW dynamics. Each soil type was characterised by a unique storage-discharge relationship and threshold response with a certain GW level above which lateral flow dominated. On the lower hillslope, predominating lateral flow and little recharge to depth is supported by hydrologically responsive soils. Connectivity between the steeper slopes and the valley bottom, however, needed persistent wet periods to overcome storage thresholds. Here, vertical flow paths recharging deeper GW dominated, with GW levels falling below the soil layer into the underlying drift. It was found that relatively well mixed, near-surface sources of stream flow predominated in wetter conditions, whilst baseflows are variable and reflect a diverse range of GW stores. Geophysics (ERT) and GW level measurements were integrated into MODFLOW-NWT to simulate GW-SW interactions along a representative 2D-hillslope transect. Although only a preliminary model, it was shown that shallow pathways have much shorter residence times, thus maintaining high water tables in the riparian peatlands, than deeper flow paths discharging through the drift and directly into the stream. Largest sources of GW are located within the drift, resulting in complex spatial patterns of runoff generation. This work illustrated the utility of a basic model to predict GW flow paths, highlighting how water and solutes are stored and released in montane headwater catchments.

The Palm Valley oasis in arid central Australia is characterised by stands of palm trees (Livistona mariae). How these unique plants, separated by nearly a 1000 kilometres of arid country from their nearest relatives persist, has long fascinated visitors. Defining the hydrogeology of the Hermannsburg Sandstone, a regionally extensive and thick Devonian sequence of the Amadeus Basin that underlies Palm Valley, is the major thrust of investigation. Appraisal of drilling data shows this aquifer to be a dual porosity fractured rock aquifer which, on a regional scale, behaves as a low permeability, hydraulically continuous resource. Groundwater is low salinity (TDS &lt1000 mg/L) and bicarbonate rich. Slight variations in cation chemistry indicate different flow paths with separate geochemical histories have been sampled. Stable isotope (????H, ???????O) results from Palm Valley show groundwater to have a uniform composition that plots on or near a local meteoric water line. Radiocarbon results are observed to vary from effectively dead (&lt 4%) to 87 % modern carbon. To resolve groundwater age beyond the radiocarbon window the long lived radioisotope 36Cl was also used. Ratios of 36Cl/Cl range from 130 to 290 x 10-15. In this region atmospheric 36Cl/Cl ratio is around 300 x 10-15. Thus an age range of around 300 ka is indicated if, as is apparent, radioactive decay is the only significant cause of 36Cl/Cl variation within the aquifer. A review of previous, often controversial, 36Cl decay studies shows results are usually ambiguous due to lack of certainty when factoring subsurface Cl- addition into decay calculations. Apparently, due to the thickness of the Hermannsburg Sandstone, no subsurface sources of Cl- such as aquitards or halites, are encountered along groundwater flow paths, hence the clear 36Cl decay trend seen. The classic homogenous aquifer with varying surface topography, the &quotToth&quot flow model, is the simplest conceptual model that need be invoked to explain these isotope data. Complexities, associated with local topography flow cells superimposed on the regional gradient, signify groundwater with markedly different flow path lengths has been sampled. The long travel times (&gt 100 ka) indicate groundwater discharge would endure through arid phases associated with Quaternary climate oscillations. Such a flow system can explain the persistence of this arid zone groundwater-dependent ecosystem and highlight the possibility that Palm Valley has acted as a flora refuge since at least the mid- Pleistocene.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 96 p. : ill., maps (some col.). Includes abstract. Includes bibliographical references (p. 41-51).

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Nov. 30, 2009). Includes bibliographical references (p. [42]-45).

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 374-384). Also available for download via the World Wide Web; free to University of Oregon users.