Water with entrained disease-causing virus entering soil normally passes through water saturated and unsaturated regions before reaching the groundwater. Twelve experiments were conducted to evaluate the effect of saturated versus unsaturated flow, and the effect of organic matter in unsaturated flow on the survival and transport of a virus, MS-2 bacteriophage, in soil columns. Additional experiments were conducted to characterize the soil, to assure that the experimental equipment did not remove virus, and to determine the extent of reversible adsorption of virus to soil. The virus were added to well water and applied to soil columns 0.052 m in diameter and 1.05 m long. KBr was used as a chemical tracer. In two experiments organic matter in the soil water was increased by using soil humic material or extract from sewage sludge. The soil material was Vint loamy fine sand (a sandy, mixed, hyperthermic Typic Torrifluvent) mixed with recent alluvium. Water samples were extracted from 0.10, 0.20, 0.40, and 0.80 m depths through porous stainless steel samplers, and from the 1.05 m depth through the percolate tube. Four different eluants were tested to remove virus from soil, and one, tryptic soy broth, was used to elute virus after three transport experiments. For saturated flow the virus concentrations reached the influent concentration in less than 2 pore volumes (T), with a retardation coefficient R at 1.05 m = 0.80. For unsaturated flow with low organic matter the relative concentrations reached steady-state values (C/C₀)(s) ranging from a mean of 27% of inflow at 0.20 m (5 to 18 T) to a mean of 5% at 1.05 m (1 to 3.3 T). Under unsaturated conditions with increased organic matter, virus (C/C₀)(s) at 1.05 m was from 41% to 49% of influent, 8 to 10 times greater than with low organic matter. Elution permitted calculation of a partition coefficient k(p) essentially equal to 0 (saturated average k(p) = -0.07 mL/g, SD = 0.15 mL/g; unsaturated average k(p) = 0.28 mL/g, SD = 0.40 mL/g), indicating little or no adsorption of virus to soil solids. Under unsaturated flow conditions enhanced removal of this virus occurs, and the removed virus are apparently inactivated. Organic matter reduced the removal of virus during transport by unsaturated flow. Virus concentrations reached and maintained a steady-state, exponentially-declining profile with depth.

A finite-element model was developed to simulate the water flow underneath a surface point source using the Galerkin method of weighted residuals and the mixed formulation of the Richards' equation. The saturated radius usually formed during a point source test was estimated by the numerical model. Comparisons with published experimental and analytical results indicated that the model is accurate and reliable. The numerical model aids in understanding the water regime under different point source scenarios. The finite element model was coded in C++ by using an object oriented approach. This allows flexibility for future updating. Finite and infinite elements were combined to obtain a numerical solution for unbounded 1-D flow domains. The results showed that the use of infinite elements may reduce the computational time when solving the flow equations for deep profiles. Although the transient point-source problem can be solved numerically, generalized solutions were developed and their coefficients calculated by best fitting numerical results of dimensionless saturated radius and time. The solutions allow calculation of the transient saturated radius given values of the van Genuchten hydraulic function parameter "m" and dimensionless point-source application rate. The resulting generalized solutions have the advantage of reducing large volumes of data. The estimation of soil hydraulic parameters from field data by using existing flow theory is analyzed. The results obtained from these studies verified that soil type and conditions can limit field estimation of steady state data for some soils. As a consequence, estimation of steady data is highly recommended by fitting field data to empirical equations. An empirical equation for transient saturated radius as a function of time was proposed. This equation is robust to predict steady-state saturated radius. To test the applicability of point source tests, hydraulic properties were estimated from field disc and point source tests. The parameters obtained from the disc and point-source methods matched closely. An overall methodology is also given for conducting point-source tests.

The processes controlling snowpack mass balance are highly variable in time and space, requiring remote sensing to observe regional processes and intensive field observations to observe hilislope-scale phenomena. This research aims to further understanding of the processes controlling snowpack mass balance through innovative applications of remotely sensed data and statistical interpolations of ground observations. Four advancements were obtained: 1) the sensitivity of regression tree snow distribution models to digital elevation data and independent variables was quanitified; 2) improved ability to upscale point snow water equivalent (SWE) measurements at snow telemetry (SNOTEL) stations was obtained by quantifying the small-scale SWE variability surrounding these stations; 3) spatially distributed snowmelt algorithms were improved by incorporating remotely sensed snow-surface albedo data into snowmelt modeling; and (4) the temporal and spatial continuity of regional-scale estimates of snow covered area (SCA) and SWE were improved by combining remotely sensed data and air temperature data to extend estimates beneath the cloud cover.

Thesis (Ph. D. - Renewable Natural Resources)--University of Arizona, 2001. / Page 189 missing in original volume. There are two pages numbered 190. Includes bibliographical references (leaves 329-334).

Thesis (Ph. D.)--Oregon State University, 1998. / Typescript (photocopy). Includes bibliographical references (leaves 162-169). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 103-105.

Over the past 50 years, complex scientific and social problems, defined as those for which the facts are uncertain, the risks great and the time frame for resolution short, have imposed demands on the scientific community to conduct scientific research that incorporates knowledge from stakeholders and expands beyond the boundaries of a single discipline. Responding to these demands, new scientific research concepts and methods have been developed and are still evolving. Beginning with the seminal work by Silvio Funtowicz and Jerome Ravetz on post normal science, this thesis traces the development of post normal science through the literature and examines the development and analysis of the three main components of transdisciplinarity: (a) problem identification; (b) knowledge production arising out of integrated research efforts by stakeholders and scientists from multiple disciplines; and, (c) the implementation of those research results. Transdisciplinarity will remain merely a concept and not a viable methodology until researchers are willing to engage in better ways to communicate, view, and process information, establish priorities and accept the methodologies of other disciplines. Further, transdisciplinarity will not realize its potential so long as researchers do not use the research process to both educate stakeholders and to be educated by stakeholders and also participate in the political arena in order to translate research into action.

In this thesis, we study traveling wave solutions to Richards equation in diffusive form which describes wetting fronts in vertical infiltration of water into one-dimensional periodically layered soils. We prove the existence and uniqueness of traveling waves solutions under prescribed flux boundary conditions and certain constitutive conditions on the diffusivity and conductivity functions in the equation. Furthermore, we show the long time stability of these traveling wave solutions under these conditions. The traveling waves are connections between two steady states that form near the ground surface and deep in the soil. We derive an analytical formula for the speed of these traveling waves which depends on the prescribed boundary fluxes and the steady states. Both analytical and numerical examples are found which show that the wave speed in a periodically layered soil may be slower, the same, or faster than the speed in a homogeneous soil. In these examples, if the phases of the diffusivity and conductivity functions are the same, the periodic soils slow down the waves. If the phases differ by half a period, the periodic soils speed up the waves. We also present numerical solutions to Richards equation using a finite difference method to address cases where our constitutive conditions do not hold. Similar stable wetting fronts are observed even in these cases.

Osmosis occurs when two solutions of differing osmolar concentrations are separated by a membrane permeable to the solvent but not to the solutes. In osmosis, water flows spontaneously from the low concentration source solution to the high concentration driving solution. This dissertation examines forward osmosis as a low-technology, lowenergy use process for hydration and dehydration of aqueous solutions. The fundamental mechanical device is a continuous counterflow extractor which incorporates a semipermeable membrane separating the source and driving solutions. The counterflow design permits maximum water recovery from the source solution and maximum dilution of the driving solution. The nonlinear differential equations describing the water and solute flows in the extractor are solved using analytical and numerical techniques. The resulting mathematical models contain design equations which can be used to determine the optimum membrane transport characteristics, optimum membrane size, and the asymmetric membrane orientation which minimizes concentration polarization. Theoretical and experimental results compare well. Two applications discussed in detail are the production of potable water from seawater using human nutrients, and fertilizer-driven forward osmosis (FDFO) for converting saline water to irrigation water. In these applications, the final desalted product is not pure but contains the human or plant nutrient used to drive the process. For extracting drinking water from seawater, 1 kilogram of nutrient powder can extract 6 kilograms of fresh water from one osmolal seawater, thus reducing the storage weight for food and water aboard a lifeboat by a factor of seven. The product water contains approximately 14 weight percent nutrients. Other driving solutions can be used as well. One kilogram of ethanol can extract approximately 20 kilograms of drinking water from seawater with the alcohol concentration of the resulting drinking water product being four to five weight percent. For converting saline water to irrigation water, FDFO can economically extract 80 kilograms of water per kilogram of fertilizer from 3200 mg/1 (0.1 osmolal) brackish water and 14 kilograms of water per kilogram of fertilizer from seawater. For open greenhouses, these quantities of water represent 24 and 4 percent of the total irrigation requirements, respectively. A final evaluation of the economic feasibility of FDFO requires more information on low-pressure membrane transport properties, costs, and lifetimes. For pure water production from seawater, the forward osmosis extractor can employ an easily removable and recyclable driving solute such as sulfur dioxide. The ten kilocalories per kilogram of water low temperature (100 °C) energy for removing and recycling the sulfur dioxide can be supplied by waste heat, by solar heating, or by burning crop wastes.

From the standpoint of real-time reservoir operation, the multipurpose control problem may be reduced to a dual purpose problem of (1) short-range control, which aims at reducing high flows and (2) longrange control, which aims at augmenting low flows and distributing stored water after the flood has receded. A decision framework for short-range reservoir control is formulated under three postulates: (1) The input to the control model is a stochastic forecast of the reservoir inflow process. (2) The control process is guided by a preference criterion which reflects the reservoir manager's value judgments concerning preferences over operating attributes, trade-offs between reservoir purposes, and attitude toward risk. (3) The long-range control is imbedded into the short-range control through the attribute space of the preference criterion, which allows for explicit consideration of the trade-offs between reservoir purposes, and through the state space and time domain of the control process, which allows for maintaining the continuity of the control. This investigation focuses on development of a preference criterion and on formulation of a control model. The preference crite- Huais developed within the framework of utility theory. The value judgments of the reservoir manager are quantified in terms of a two-attribute disutility function. It is argued that minimization of expected disutility is a plausible and well motivated criterion for reservoir control under uncertainty. A suitable disutility model is developed. The case of a group decision maker is analyzed in depth, and a methodology for obtaining a group disutility function is proposed. Some principles and techniques for assessing disutility functions are advocated; they are motivated by results of psychological research in human decision behavior, and are further supported by experimental evidence. Results of assessment of the reservoir control disutility function for several single and group decision makers are presented. The reservoir control process is conceptualized in the form of two sub-processes: (1) Forecast-Strategy Process, which is modeled as an open-loop feedback controller and (2) Control Process, which is modeled as a truncated Markovian adaptive controller. The optimal control strategy is selected on the basis of the preference criterion. A set of measures of effectiveness is proposed for evaluating the past performance of the controller. Computational aspects of the control model are analyzed. Certain monotonicity properties of the optimal control strategy are proven, and two suboptimal control strategies are derived: (1) partial open-loop strategy and (2) naive/partial open-loop strategy.