This thesis presents the results of groundwater flow modeling completed to simulate the effects of construction dewatering during the advance of a bedrock tunnel through an aquifer that serves as the source of water for numerous adjacent domestic water wells. The modeling was retrospective and consequently a large amount of data collected during the course of the tunnel project was available for the purpose of model calibration. Actual drawdown levels due to tunnel dewatering resulted in a significant number of well interference problems. The model was constructed through the application of standard groundwater flow modeling techniques using the United States Geological Survey's modular groundwater flow modeling program (MODFLOW), and was designed to provide a reasonable representation of the groundwater flow system within which the tunnel was constructed. The model simulated the tunnel as a drain which advances with time through the use of successive stress periods. An evaluation of grouting efforts that were undertaken to reduce the rate of groundwater inflow to the tunnel was completed. (Abstract shortened by UMI.)

A field study was conducted in 1994 and 1995 to understand the interaction of groundwater and surface water in the Raisin River watershed, near Cornwall, Ontario. The Raisin River lies within an agricultural region which relies heavily on groundwater use. The regional groundwater supply is predominantly from a limestone aquifer which underlies various surficial deposits (primarily glacial till). Groundwater movement appears to be in a southeasterly direction, towards the St. Lawrence River. Seepage meters, mini-piezometers, and a falling head permeameter were used to (i) measure the flux of groundwater into (positive seepage) or out (negative seepage) of the Raisin River, and (ii) measure the hydraulic conductivity of the Raisin River sediments. Measurements were made at thirteen sites within the watershed. To identify the source of groundwater and study processes of streamflow generation during storm runoff, surface water, groundwater, and rainwater samples were collected for environmental isotopes (oxygen-18 and deuterium). Raisin River discharge data were also analysed. Seepage measurements and hydraulic conductivities exhibit significant variability. The coefficients of variation for seepage measurements ranged from 20.3 to 392%, and for hydraulic conductivity from 0 to 161%, depending on the site. Seepage flux ranges from $2.23\times10\sp{-6}$ to $\rm{-}9.82\times10\sp{-9}m\sp3m\sp{-2}s\sp{-1},$ and hydraulic conductivity ranges from 10$\sp{-6}$ to 10$\sp{-9}$ ms$\sp{-1}$ (a negative seepage flux indicates groundwater flow from the aquifer to the river). Environmental isotope analyses indicate that meteoric water is the source of local groundwater with a mean residence time of approximately 4 months. After a storm event, groundwater composed 63% of total stream discharge. The peak response in the river is approximately two days after a storm event. These variables indicate that groundwater/surface water relationships should be taken into account if decisions are made with respect to water quality or quantity. (Abstract shortened by UMI.)

Peak seasonal discharge takes place after snowmelt in 1994 as meltwater production was amplified by more exposed glacier ice which was indicated by exponentially increasing diurnal discharge amplitude. Air temperature strongly influenced discharge in both years and precipitation was infrequent with limited influence. Discharges in 1994 were under-competent. Diurnal clockwise hysteresis defines the short term relation between suspended sediment concentration and discharge but current explanations fail to explain its frequency. Respectively, the dominant cations are Ca$\sp{2+},$ Mg$\sp{2+},$ K$\sp{+}$ and Na$\sp{+},$ and each has a strong positive relation with conductivity. Conductivity, and thus individual cation concentrations, decrease over both seasons and are inversely related to discharge. Diurnal conductivity amplitude was greatest with glacier melt and clockwise hysteresis defines the short-term relation between discharge and conductivity.

Abstract not available.

A deposit-scale study of hydrochemical processes has been conducted at the Halfmile Lake and Restigouche massive (Zn-Pb-Cu-Ag) sulphide deposits, Bathurst Mining Camp (BMC), New Brunswick, Canada. Both the Halfmile Lake and Restigouche deposits are hosted in a deformed sequence of Ordovician (465 Ma) felsic volcanic rocks with similar topography and climate. Groundwater flow is dominated by fracture-flow. The two deposits differ in that the Halfmile Lake deposit is steeply dipping with steep structures whereas the Restigouche deposit is closer to surface with shallower structures. Groundwaters were collected using flow-through bailers and a straddle-packer system that permits recovery of groundwaters from a discrete depth interval. In fracture-controlled rocks, straddle-packer groundwater compositions are more depth representative than bailer groundwaters. Geochemical modelling and stable isotopic compositions indicate that shallow Ca-HCO3 groundwaters are produced by modern meteoric recharge and the major solutes are controlled by dissolution of fracture and vein carbonate and silicate hydrolysis. The Ca-SO4 groundwaters reflect oxidation of the sulphide minerals by modern recharge waters. Deeper brackish to saline groundwaters from the Restigouche, Heath Steele, Brunswick #12, Stratmat Main Zone, and Willett deposits have heavier oxygen and deuterium isotopic compositions than shallow groundwaters indicating older recharge under warmer climates. Interaction between oxygenated recharge waters at the Restigouche and Stratmat Main Zone deposits has resulted in elevated levels of metals (e.g., up to 4000 m g/L Pb and 5300 m g/L Zn) which, based on geochemical modelling and borehole geophysics (self-potential anomalies), are produced by sulphide oxidation. Surface waters collected from the Halfmile Lake and Restigouche deposit primarily represent groundwater discharge based on the compositional and stable isotopic similarity with shallow groundwaters. Geochemical and isotopic modelling indicates that the major solute compositions are controlled primarily by the underlying lithologies and dissolution of carbonate. Although sulphide-associated metals (Zn, Cd, Pb, Cu, Fe) in surface waters at the Halfmile Lake and Restigouche deposits are low compared to streams draining other deposits and mine tailings, anomalously high values (with respect to local background) occur proximal to the Restigouche massive sulphides. The generally neutral pH values in the BMC results in more subtle base metal anomalies in surface waters which indicates that detailed sampling is required for hydrogeochemistry to be an effective exploration tool in the BMC. Groundwaters have higher base metal abundances and display greater contrast between anomalous and background compositions such that groundwaters have potential in better outlining mineralized targets during a drilling program.* (Abstract shortened by UMI.) *The appendices are presented on CD-ROM in Microsoft Excel and Adobe Acrobat format with "xl" and "pdf" suffixes, respectively. The files are readable on Macintosh computers as well as Windows 95 and Windows NT.

The present research investigates the numerical and experimental modelling aspects of flow in compound channels, with special interest in the transport of inert pollutant aspects. This is examined through developing a 2-D finite difference mathematical model, (CHAT: Compound-channel Hydraulics And Transport), to solve the flow and transport equations for open channels having compound cross-sections. The numerical computation of open-channel flows requires preparing and processing larger volumes of boundary and bathymetry data for computer inputs and the development of numerical algorithms for treating complex boundary condition, channel properties, and free surface effects. Derivation of the basic differential equations is based on the Navier-Stokes equations of continuity and fluid motion, in addition to the convection-dispersion equation. These equations are derived in three dimensions (3-D), however, in order to simplify the problem and ease the computational effort, the equations are integrated over the depth (depth-averaged). Most finite difference methods for calculating the convection portion of the transport equation are plagued by artificial (numerical) diffusion. This is sometimes stronger than the physical diffusion and can render the calculations useless. Therefore, as far as reliability of the results is concerned, selection of the numerical scheme is critical. Data for the verification and validation of the developed mathematical model was obtained through dye-tracer experiments performed in a large concrete channel of the Hydraulics Laboratory, University of Ottawa. Consideration was limited to conservative, non-buoyant material. The study investigates the impact on the mixing processes of strong lateral momentum transfer effects associated with severely compound flow fields. The experiments include measurements of dye concentrations downstream from slug-injection or steady-injection point source(s). Longitudinal and transverse mixing coefficients were calculated using the method of moments and by estimation using empirical relationships. In general, it is not possible to obtain analytical solutions to the dispersion equation in natural waterways with arbitrary boundary conditions. However, a variety of exact solutions exists for idealized situations, which can be useful in obtaining order-of-magnitude estimates. These exact simplified solutions were applied to our experimental data. The comparison between measured and predicted concentration curves by the developed model shows a level of agreement in the general shape, peak concentrations and time to peak. Different statistical methods were considered in evaluating the simulated results.

The purpose of this research is twofold. First, a tool is developed to assist in the reproduction of field correlation scenarios for input into a flow and transport simulator. Second, this tool is used to generate random fields with several different velocity/retardation relationships typical of the Canada Forces Base Borden aquifer in order to determine the effect of this relationship on the retardation and dispersive processes, specifically on the macrodispersivity. The second section of the research investigates the effect of different types of spatial statistics on the behaviour of a contaminant travelling through saturated, heterogeneous porous media. The non-reactive plume travels significantly farther than the reactive plume, even when considering the effects of retardation. Transverse macrodispersivities are sensitive to changes to neither the correlation within fields, nor the correlation between velocity and retardation fields for both the reactive and non-reactive solute plumes. Longitudinal macrodispersivity for a reactive solute is significantly different than that for a non-reactive solute: the effect of the chemical heterogeneities is to enhance reactive solute macrodispersivities relative to non-reactive macrodispersivities for a negative cross-correlation between velocity and retardation, and to decease reactive solute macrodispersivities relative to non-reactive macrodispersivities when the cross-correlation is positive. (Abstract shortened by UMI.)

Precipitation and runoff records from several burned watersheds have been used to evaluate the performance of the Automated Geospatial Watershed Assessment (AGWA) tool as it is used to assign parameters to the KINmatic runoff and EROSion Model 2 (KINEROS2). This modeling scheme is used by the Department of Interior Burned Area Emergency Response (DOI BAER) teams to assess flooding and erosion risk immediately following a wildfire. Although DOI BAER teams use this parameterization/modeling framework to assess the relative change in watershed behavior following a wildfire by driving the model with National Oceanic and Atmospheric Administration (NOAA) design storms, calibrations performed on actual events using rainfall estimations provided by rain gages and radar to drive the model provides insight into the model's performance, and potentially informs changes and developments to the AGWA parameter estimation scheme. Results indicate that current parameter modifications made by AGWA to represent fire impacts provide reasonable results for DOI BAER relative change risk assessments, though additional modifications to saturated hydraulic conductivity may be necessary to represent a broader range of storm intensity.

To determine if the distinct deuterium (D) and oxygen-18 (18O) signature of precipitation from a tropical storm or hurricane could be used as a natural tracer in a springshed, isotope analyses of water samples from Wakulla Spring in north Florida were done over the course of two Atlantic hurricane seasons. Water samples were collected between Feb. 10, 2012 and Aug. 27, 2012 and between March 19 and Oct. 21, 2013. Additionally, water samples and water quality data from a total of 20 springs in north and central Florida were collected between Jan. 14 and Feb. 18, 2012 during a period of prolonged drought; the springs were sampled again between Sept. 20 and Nov. 9, 2012 after rains in the summer and fall increased groundwater levels. The δD and δ18O values of the samples from the 21 springs, including Wakulla Spring, showed that the springs during non-baseflow conditions have much more variability in isotope composition than they had have during baseflow conditions. Comparison between the two sets of samples provided a range in isotope values for springs fed by the Upper Floridan aquifer. The 2012 hurricane season had one major storm, Tropical Storm Debby from June 23 to 27, which brought over 500 mm (20 in) of rain to the Wakulla Springs study area. A clear signal of the tropical storm was observed in the Wakulla Spring water samples as isotopically light rain recharged the aquifer and emerged at the spring. A minimum in δD (of -30‰)and δ18O (of -5.1‰)on July 4 to 5 indicated a mean transit time of nine days from the heavy rainfall that occurred on June 25 and 26. The average isotope values during baseflow prior to the storm were -17‰ δD and -3.3‰ for δ18O. The transit time was similar to travel times found by dye trace studies of the sinking streams in the springshed. The exact isotope composition for Tropical Storm Debby was not known, so there was not enough data to apply isotope-based hydrograph separation to the streamflow record for Wakulla River. The maximum measured streamflow was documented at 2,600 cfs by an acoustic Doppler current profiler measurement on June 26, 2012. During the 2013 hurricane season, rainfall was recorded and collected for isotope analysis. No major storms reached the study area during the 2013 Atlantic hurricane season except for a weakened Tropical Storm Andrea which brought a small amount of rain on June 6 (2.27 in, 58 mm). The precipitation had very negative isotope values (δD = -109‰ and δ18O = -14.7‰). A minimum δ18O value of -4.1‰ was seen in Wakulla Spring samples 29 and 33 days later but it was not clear if these values could be attributed to the very small amount of isotopically light precipitation since precipitation samples from a few other intense summer storms during the month had values slightly more negative than -4.1‰. The use of tropical storm precipitation was shown to be an effective and simple method for studying the hydrology of a springshed with the potential for very light isotope composition of rainfall distributed over a large land area and a very distinct signal in springflow. The drawbacks are that the opportunities to apply the method are limited by the unpredictable occurrence of tropical storms and hurricanes and that a two-component mixing model for hydrograph separation may not provide enough information for watersheds with complex hydrology. The use of tropical storm or hurricane precipitation as a natural tracer in a springshed would work well in ongoing studies of springs, where the information it provides could be added to geochemical tracer data and isotope data for other components of aquifer storage. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the Master of Science. / Spring Semester 2016. / March 21, 2016. / isotopes, Wakulla Springs / Includes bibliographical references. / Yang Wang, Professor Co-Directing Thesis; Jeffrey P. Chanton, Professor Co-Directing Thesis; William M. Landing, Committee Member.

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