The water level in an open well tapping a confined formation is influenced by natural forces including the solid Earth tide (SET) and atmospheric pressure variation (APV). The spectral method is used to derive an analytical solution for well response to both the random and the periodic components of the combined SET and APV (CSA) forcings. Previously posed models for the individual SET and APV forcings are subsets of this more general model. An inverse theory and an algorithm are developed in order to provide improved results when using such models to estimate the hydraulic parameters associated with a given formation. A complex vector estimation criterion is used in developing a nonlinear, Gauss-Marquardt estimation algorithm. When compared to previous methods of fitting modulus and phase, the complex vector estimation methodology has less bias and variance, and is more robust. An examination of the response surface of the estimation criterion reveals that storativity (S) is relatively non-unique, and thus is not considered in the context of the parameter estimation problem. However, since there is little correlation between transmissivity (T) and S estimators, a good estimate for T is still possible independent of having knowledge of S. An estimate of T is possible only if the data contain sufficient information so that the analysis occurs within an identifiability window, which is defined with respect to the dimensionless transmissivity of the system. The CSA estimation methodology is compared to individual SET and APV schemes. The CSA scheme gives the greatest probability that sufficient information is contained in a data record so that T is identifiable. The results of applications to synthetic data indicate that the OEA scheme gives a T estimate with the most precision, and also that it requires collecting fewer observations.

Samples of ordinary copper, hot-isotactically-pressed (HIP) copper, and simulated borosilicate high-level waste glass were leached at 25°C, 51°C, and 80°C in solutions simulating brine and silicate groundwaters. It was found that the amount of glass leached increased at higher temperatures, and more leaching occurred in brine than in silicate groundwater. This behavior is predicted by Le Chatelier's Principle. Similarly, more copper was dissolved at higher temperatures, and more was dissolved in brine than in silicate groundwaters.

The focus of this study was on recharge mechanisms and recharge estimation within the Table Mountain Group area. The study evaluated recharge processes and recharge estimation methods in the Table Mountain Group aquifer systems.

A research report submitted to the Faculty of Science school of Geosciences in partial fulfillment of the requirements for the degree of Masters of Science in Hydrogeology. Johannesburg, June 2017. / The Masama Sandstone Aquifer is located in a semi-arid region of south-eastern Botswana where there are no perennial rivers. Groundwater is the main source of water supply for the communities. Historically many water drilling programs have been carried out in this area and the hydrogeological system has been conceptualized. An integrated approach coupling environmental isotopes, radioisotopes and multivariate statistical analysis of the hydrochemical variables was employed to study the origin, age, recharge conditions, rock-water interaction and the hydrological link between the aquifer and geological structures. The major ions in this area are Na+, Ca2+, Mg2+ and HCO-3. Groundwater in the Masama area fall in the transition from a Na-HCO-3 –type through Ca-Na-HCO-3 to Ca-Mg-HCO-3 -type waters from the western to the eastern part of the area. The water types are as a result of cation exchange, carbonate dissolution and rock-weathering processes. The δ18O and δ2H values vary spatially depending on the source of moisture, rainfall season, geology, topography and groundwater circulation depth. Deep circulating groundwaters are isotopically depleted whilst shallow circulating groundwaters are isotopically enriched with respect to winter rain. Low tritium values < 0.8TU and 14C values < 80pmc testifies for recharge. Recent rainfall amount in the area is not sufficient enough to make a profound replenishment in the aquifer. Tritium, 14C and Chloride Mass Balance helped in identifying recharge location and hydrologic connections between structures and the sandstone aquifer elucidating that recharge zones are in the NE and NW of the study area. High recharge rates occur in the north-eastern part and the Makhujwane fault act as a conduit for groundwater recharge. This study provides a better understanding of the aquifer and the information contained herein can be incorporated into future works for sustainable use of the groundwater resource. / XL2017

The mechanisms responsible for overland transport of faecal pathogens, particularly Cryptosporidium oocysts, from animal sources to water bodies are not fully understood. Surface properties of microbes, such as electrostatic charge and hydrophobicity, are thought to contribute to their aggregation and attachment to solid surfaces. There is conflicting evidence that methods used to purify Cryptosporidium oocysts from faecal material may affect the oocyst surface, leading to biased conclusions from transport studies. By studying oocyst surface properties, aggregation and soil attachment, this thesis addressed whether oocyst purification methods influence overland transport studies, and whether oocysts are likely to be associated with particles during transport. When using the microbial adhesion to hydrocarbon (MATH) assay with octane, oocyst hydrophobicity was shown to be method and isolate dependent, with oocysts displaying moderate to high hydrophobicity in 0.01 M KNO3. There was no observed attachment, however, to the hydrophobic octyl-SepharoseTM bead ligands when using the same suspension solution. Oocyst age did not appear to influence their hydrophobicity. A small but statistically significant proportion of oocysts displayed a net negative surface charge as observed by their attachment to an anion exchange ligand (DEAE). There was no difference in hydrophobicity or surface charge observed between purified oocysts and oocysts that had been extracted without the use of harsh chemicals and solutions with dehydrating properties. Purified oocysts did not aggregate at pH values between 3.3 and 9.0, nor in solutions lower than 0.59 M in ionic strength at a pH 2.7 which is approaching the reported isoelectric point of oocysts. This finding suggests that oocysts may not form aggregates under general environmental conditions. The association of purified oocysts with soil particles was observed in settling columns. Attachment to soil particles was not conclusive since the settling of the soil particles may have entrained single oocysts. Nonetheless, approximately 27% of oocysts were estimated to be unbound to soil or associated with small soil particles. Hence models for oocyst overland transport should consider a significant fraction as single entities or associated with soil particles less than about 3 μm in size.

The process of calibrating a numerical model is examined in this thesis with an application to the flow of groundwater in the Willunga Basin in South Australia. The calibration process involves estimating unknown parameters of the numerical model so that the output obtained from the model is comparable with data that is observed in the field. Three methods for calibrating numerical models are discussed, these being the steepest descent method, the nonlinear least squares method, and a new method called the response function method. The response function method uses the functional relationship between the model's output and the unknown parameters to determine improved estimates for the unknown parameters. The functional relationships are based on analytic solutions to simplifed model problems or from previous experience. The three calibration methods are compared using a simple function involving one parameter, an idealised steady state model of groundwater flow and an idealised transient model of groundwater flow. The comparison shows that the response function method produces accurate estimates in the least amount of iterations. A numerical model of groundwater flow in the Willunga Basin in South Australia has been developed and the response function method used to estimated the unknown parameters for this model. The model of the Willunga Basin has been used to examine the sustainable yield of groundwater from the basin. The effect on groundwater levels in the basin using current and estimated extraction rates from the literature for sustainable yield has been examined. The response function method has also been used to estimate the rate of extraction to return the groundwater levels at a specific location to a desirable level. / Thesis (M.Sc.)--Department of Applied Mathematics, 2001.

Thesis (M.S.)--University of Nevada, Reno, 2005. / "December, 2005." Includes bibliographical references. Online version available on the World Wide Web.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available online.

Thesis (M.S.)--University of Nevada, Reno, 2005. / "December 2005." Includes bibliographical references (leaves 69-72). Online version available on the World Wide Web.