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DisciplineGraduate College (195)

Hydrology and Water Resources (195)

AuthorsNeuman, Shlomo P. (28)Ince, Simon (26)Evans, Daniel D. (25)Sorooshian, Soroosh (25)Simpson, Eugene S. (23)Davis, Donald R. (20)Harshbarger, John W. (19)Warrick, Arthur W. (17)Davis, Stanley N. (14)Maddock, Thomas (14)View MoreTypes
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SubjectsAcid deposition -- Sierra Nevada (Calif. and Nev.) -- Mathematical models. (1)Acid mine drainage -- Environmental aspects -- Arizona -- Pinal Creek Watershed. (1)Agriculture, Plant Culture. (1)Agriculture, Soil Science. (4)Alluvial fans -- Mathematical models. (1)View More
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Innovative tracers for subsurface characterization

Nelson, Nicole Terese (The University of Arizona., 1999)

Proper site characterization is a critical component in making risk-based decisions and in selecting an appropriate action for a site, whether it is active remediation, containment or natural attenuation. The overall purpose of this work is to investigate innovative techniques for characterizing the factors controlling the transport and fate of organic chemicals at contaminated sites. It is expected that results from this work will lead to improved and more cost-effective methods for characterizing contamination at hazardous waste sites. The information gained from using these methods may lead to a better understanding of factors controlling contaminant transport at sites and therefore more informed risk-based decision making and selection of remediation strategies. The results indicate that (1) the presence of porous media heterogeneity and distinct zones of dense nonaqueous liquid (DNAPL) saturation lead to reduced performance (reduced accuracy) of the partitioning tracer test for measuring DNAPL saturation in saturated subsurface systems, (2) gas-phase tracer tests have the potential to accurately measure water contents for a system with uniform water content and homogeneous porous media, (3) the diffusivity-tracer test method can be used to determine whether diffusion-mediated processes are significant at a particular site, and (4) for a 2-dimensional flow cell flushing experiment the magnitude of trichloroethene concentration and the shape of the trichloroethene elution curves varied as a function of location and sampling type and that the less than solubility concentrations observed at almost all ports were caused by the nonuniform NAPL distribution and porous media heterogeneity, rather than by rate-limited interphase mass transfer at the pore-scale.

Operations policy for the Upper Pampanga River Project reservoir system in the Philippines

Franco, Danielito Tan,1946- (The University of Arizona., 1977)

This study is an application of the simulation-dynamic programming approach for the evolution of a water regulation policy for the Pantabangan reservoir of the Upper Pampanga River Project, in conjunction with two tributary reservoir systems: the Aurora Transbasin Diversion Project and the proposed Casecnan River Project. The study may be decomposed into three sequential phases: 1) a reservoir operations simulation study of the existing two-reservoir system and the three-reservoir configurations for three alternative Casecnan dam locations. The operations simulation was centered at the Pantabangan reservoir and was performed under parametric conditions of invariant service area cropping pattern, power generation, flood control release schedules, and average system microclimate. The principal variables were the reservoir system and service area runoffs which were inputted as synthetic streamflow traces. The results of the simulation study, in the form of Pantabangan irrigation and power releases, were inputted for optimization in 2) a dynamic programming model which is of the explicit stochastic type. The probabilistic property of the model is ascribed to the use of lag-one monthly transition probability matrices and relative frequency matrices to respectively characterize the behavior of the unregulated Pantabangan reservoir inflows and the transbasin diversions. Due to the rough discretization procedure conducted on the optimization variables, the determined operations policy was tested in 3) a feasibility simulation model which features essentially the same parameters and variables of the operations model. Two sets of policies were tested under the two- and three-reservoir arrangements. The first is a constrained policy based on a minimum Pantabangan reservoir storage greater than the physical minimum. The unconstrained policy was based on dead storage as the minimum.

Methodology for long-term water supply planning : Mexico City case

Aguilar-Maldonado, Alexis (The University of Arizona., 1979)

A complete methodology for long-term water supply planning is presented. Based upon the characteristics of the water resources development planning problem (nonlinearity of cost functions, and hydrologic variables), the author rejects the seeking of "optimal" solutions and supports the seeking of "good enough" solutions. To answer the questions that are involved in long-term water supply planning, it is proposed to break down the problem into two simpler ones to be solved in a sequential fashion. Although mathematical guarantee of optimality cannot be assured, the introduction of physical and engineering constraints greatly increases the confidence in the final results. The proposed methodology allows deep analysis of the hydrologic aspects involved in water resources planning. The depth of hydrologic analysis is only restricted by available data and technology. In this respect, a method for synthetic generation of monthly runoff records in ungaged streams is proposed. An application of the methodology to the development of a Mexico City water supply plan is presented in full detail to appreciate its usefulness. Mexico City population forecast for the year 2000 is 28 million people. The estimated water demand in that year is 105 m³/sec, more than twice the present water supply of 50 m³/sec. To satisfy this demand, water has to be brought from four basins more than 150 km distant, and located at elevations more than 1,000 m below Mexico City's elevation (2,300 m above mean sea level). The water supply plan which resulted from this study indicates the most recommendable sequence for the development of the four basins, and the amount of water to be obtained from each one.

Parameter estimation for hydrometeorological models using multi-criteria methods

Bastidas, Luis Alberto, 1950- (The University of Arizona., 1998)

There are three components of error in the ability of land-atmosphere models (e.g., BATS, SiB, etc.) to simulate/predict observed land-surface state variables and output fluxes (e.g. lambdaE, H, Tg, Q, etc.). The first is caused by model structural error associated with simplifications and/or inadequacies in the functional representations of underlying physical processes. The second component is measurement error associated with the input and output data. The third is caused by error in specification of the values of the model parameters. Automatic parameter tuning (model calibration) methods allow minimizing of the parameter error, thereby obtaining an estimate of the remaining error components. This work describes an automatic multi-criteria approach and its use to tune all 27 parameters of the BATS model using data measured in the field. The parameters were adjusted to simultaneously optimize the ability of the model to reproduce observed values of several output fluxes and/or state variables (e.g., latent heat flux, sensible heat flux, ground temperature, etc.). The results indicate that not only does the procedure result in conceptually reasonable and consistent parameter estimates, but the calibrated model is able to provide significant improvement in performance (33% or more reduction in error) over the "un-calibrated" model (i.e., using the BATS default parameter values for the associated region). Substantial improvements of this kind can have important implications for studies that seek to evaluate alternative model structures or to regionalize parameters. To reduce the dimensionality of the optimization problem a multi-criteria extension of the Regionalized Sensitivity Analysis (RSA) has been developed.

Integrated hydrogeochemical modeling of an alpine watershed: Sierra Nevada, California.

Wolford, Ross Alan. (The University of Arizona., 1992)

Seasonally snow covered alpine areas play a larger role in the hydrologic cycle than their area would indicate. Their ecosystems may be sensitive indicators of climatic and atmospheric change. Assessing the hydrologic and bio-geochemical responses of these areas to changes in inputs of water, chemicals and energy should be based on a detailed understanding of watershed processes. This dissertation discusses the development and testing of a model capable of predicting watershed hydrologic and hydrochemical responses to these changes. The model computes integrated water and chemical balances for watersheds with unlimited numbers of terrestrial, stream, and lake subunits, each of which may have a unique, variable snow-covered area. Model capabilities include (1) tracking of chemical inputs from precipitation, dry deposition, snowmelt, mineral weathering, baseflow or flows from areas external to the modeled watershed, and user-defined sources and sinks, (2) tracking water and chemical movements in the canopy, snowpack, soil litter, multiple soil layers, streamflow, between terrestrial subunits (surface and subsurface movement), and within lakes (2 layers), (3) chemical speciation, including free and total soluble species, precipitates, exchange complexes, and acid-neutralizing capacity, (4) nitrogen reactions, (5) a snowmelt optimization procedure capable of exactly matching observed watershed outflows, and (6) modeling riparian areas. Two years of data were available for fitting and comparing observed and modeled output. To the extent possible, model parameters are set based on physical or chemical measurements, leaving only a few fitted parameters. Thc effects of snowmelt rate, rate of chemical elution from the snowpack, nitrogen reactions, mineral weathering, and flow routing on modeled outputs are examined.

A METHODOLOGY FOR PLANNING LAND USE AND ENGINEERING ALTERNATIVES FOR FLOODPLAIN MANAGEMENT

Weisz, Reuben N. (The University of Arizona., 1973)

Parallel finite element algorithm for transient flow in bounded randomly heterogeneous domains

Ye, Ming (The University of Arizona., 2002)

We consider the effect of randomness of hydraulic conductivities K(x) on numerical predictions, without resorting to either Monte Carlo simulation, of transient flow in bounded domains driven by random source, initial and boundary terms. Our aim is to allow optimum unbiased prediction of hydraulic heads h(x, t) and fluxes q(x,t) by means of their respective ensemble moments, c and < q(x,t)>c, conditioned on measurements of K(x). These predictors have been shown by Tartakovsky and Neuman (1998) to satisfy exactly a space-time nonlocal (integro-differential) conditional mean flow equation in which < q(x,t)>c is generally non-Darcian. Exact nonlocal equations have been obtained for second conditional moments of head and flux that serve as measures of predictive uncertainty. The authors developed recursive closure approximations for the first and second conditional moment equations through expansion in powers of a small parameter σᵧ , which represents the standard estimation error of ln K(x). The authors explored the possibility of localizing the exact moment equations in real, Laplace- and/or infinite Fourier-transformed domains. In this paper we show how to solve recursive closure approximations of nonlocal first and second conditional moment equations numerically, to first order in σ²ᵧ, in a bounded two-dimensional domain. Our solution is based on Laplace transformation of the moment equations, parallel finite element solution in the complex Laplace domain, and numerical inversion of the solution from the Laplace to the real time domain. We present a detailed comparison between numerical solutions of nonlocal and localized moment equations, and Monte Carlo simulations, under superimposed mean-uniform and convergent flow regimes in two dimensions. The results are shown to compare very well for variances σ²ᵧ as large as 4. The degree to which parallelization enhances computational efficiency is explored.

Modeled sensitivities of the North American Monsoon

Gochis, David (The University of Arizona., 2002)

The North American Monsoon System (NAMS) is an important climatological feature of much of southwestern North America because it is responsible for large portions of the annual rainfall in many otherwise arid and semi-arid environments. This dissertation explores issues related to numerical simulation of the North American Monsoon climate. Simulation studies using both an atmospheric general circulation model (AGCM) and a regional climate model (RCM), forced by model analyzed boundary conditions, are presented. The RCM was run for a single season with three different convective parameterization schemes for a single season to assess the sensitivity to convective representation. The main conclusion from these simulations was that substantial differences in both the time-integrated thermodynamic and circulation structures of the simulated July 1999 NAM atmosphere evolve in the simulations when different convective parameterization schemes (CPSs) are used. All simulations reproduced the maximum of precipitation along the western slope of the Sierra Madre Occidental. However, root mean squared errors and model biases in precipitation and surface climate variables were substantial, and showed strong regional dependencies between each of the simulations. There are large differences in the modeled monthly-total surface runoff between simulations. These differences appear to be more closely related to differences in local, precipitation intensity than to time-average or basin-average intensity. It was found that many features of the North American Monsoon were poorly simulated by the AGCM used in its current configuration when using a yearly repeating cycle of sea-surface temperatures. In particular, the model is unable to simulate the regional patterns of monsoon circulation and rainfall. Modeled rainfall over the southwest U.S. and Mexico is much too low, while tropical precipitation is overestimated. Anomalous sea-surface temperature forcing in the Pacific Ocean also induced model responses that resemble observed responses suggesting that sea-surface temperatures may play a modest role in establishing the monsoon circulation and hence in the generation of monsoon rainfall.

Higher-order effects on flow and transport in randomly heterogeneous, statistically anisotropic porous media

Hsu, Kuo-Chin, 1963- (The University of Arizona., 1996)

A higher-order theory is presented for steady state, mean uniform saturated flow and nonreactive solute transport in randomly homogeneous, statistically anisotropy natural log hydraulic conductivity fields Y. General integral expressions are derived for the spatial covariance of fluid velocity to second order in the variance σ² of Y in two and three dimensions. Analytical expressions are evaluated for integrals involving first-order (in σ) fluctuations in hydraulic head in two- and three-dimensional Y fields with exponential and Gaussian correlation functions. Integrals involving higher-order fluctuations of hydraulic head are evaluated numerically. Our results show that corrections involving higher-order head fluctuations are as important as those without them; neither should be disregarded. The ratio between second- and first-order variance approximations is larger in three- than in two-dimensions, larger for transverse than for longitudinal velocity, and increases with σ². The variance of longitudinal and transverse two- and three-dimensional velocity is larger in anisotropic than in isotropic fields due to higher-order effects. Second-order mean velocity is larger than first order in three dimensions and for most anisotropy ratios (except 1-6) in two dimensions. Transport requires approximations at flow and advection levels. Our results show that, in two dimensions, the combined effects of second-order correction to flow and to advection impact transport to a greater extent than does the sum of their individual effects. The choice of Y correlation function has greater effects on macrodispersivity than does second-order correction in flow. Published two-dimensional results of Monte Carlo simulations yield macrodispersivities that lie significantly below those predicted by first- and second-order theories. Considering that Monte Carlo simulations often suffer from sampling and computational errors, that standard perturbation approximations are theoretically valid only for σ² < 1, and that Corrsin's conjecture represents the leading term in a renormalization group perturbation which contains contributions from an infinite number of high-order terms, we find it difficult to tell which of these approximations is closest to representing transport in strongly heterogeneous media with σ² ≥ 1.

Empirical studies of laminar flow in porous consolidated media

Lehr, Jay H.,1936- (The University of Arizona., 1962)

The influence of geologic factors in controlling flow patterns in hydraulic systems is evaluated by hydraulic models which are constructed as a porous consolidated media that simulates the interstitial geometry of consolidated rocks. Colored inks are injected into the flow system and are observed through the transparent sides of the model case. Visual analysis of the flow system, leads to salient conclusions concerning fundamental aspects of complex flow systems. Empirical experiments were conducted on the following aspects: Refraction of flow lines across lithologic interfaces: The law of streamline refraction, as described by King Hubbert, was found to be correct where boundary conditions do not interfere. Continuity of flow around and through highly permeable and impermeable lenses of different lithologies: The flow system around impermeable lenses indicates the nonexistence of stagnant areas where a hydraulic gradient is imposed on a saturated ground water system. Flow net system caused by a single pumping well: Transient changes of individual flow vectors, within the immediate area of influence, were analyzed at the moment pumping began. The absence of a transition phase indicates a rapid adjustment of the flow system to the pumping condition. Flow net system of mutual interference of depression cones caused by pumping multiple wells: This permitted an analysis of the ground water divide. Flow bands divided into flow paths which moved in opposite directions. Effects of emplacing pumping wells in highly permeable media: The increased area of influence of water movement to wells was clearly illustrated. This analysis demonstrates the capture of partially confined flow from great dths. The relation of the shape of artificial recharge pits to infiltration rate: Variations of flow net systems of rectangular and wedge-shaped pits were analyzed. When all other factors were held constant, the shape of the recharge pit was found to have no important effect upon recharge rate. Flow toward an effluent stream: The potential head of ground water beneath the stream was found to increase with depth. The relationship between hydraulic gradient and flow net configuration: The hydraulic gradient was found to have no effect on the flow net of a confined system, but a definite effect upon unconfined flow systems, in as much as it alters the water table which is the upper flow boundary. Flow pattern through tilted and faulted sedimentary structures: The geometric convergence of the aquifer boundaries caused the convergence of flow lines through a brecciated fault zone. A possible genesis of a hydrothermal vein ore was suggested by this flow pattern. Formation of perched water tables: The mechanisms by which saturated ground water mounds can be formed on a low permeability lens was demonstrated. Evidence was found which indicates that perched ground water probably escapes through the perching body as well as around its extremities. Confluence of gravity water and saturated flow: Unsaturated flow arriving at the water table of the saturated ground water body becomes an integral part of that body which acts as a single hydrodynamic system. Artesian ground water systems: A model illustrating the classic artesian aquifer situation was constructed, andflowing and non-flowing artesian wells were studied. A ground water mound was formed in the water table aquifer by water discharging naturally from the artesian aquifer through a fault in the confining layer. Subsidence around a pumping well: Water was pumped from a simulated artesian well, the piezometric surface in the vicinity of the well was lowered and the overburden was observed to subside while compressing the artesian aquifer. Cone of depression formed around single and multiple well systems: The drawdown at any point within the area of influence of a multiple well system was shown to be equal to the sum of the individual drawdowns of each well in the multiple well system, provided recharge and evaporation are neglected. Information resulting from these studies will provide guides for scientific development and exploitation of ground water supplies. Contributions were made that will advance the use of hydraulic models as exploratory tools in scientific hydrology. Further, this work brought into focus the importance of hydraulic models as couinunication media for interpreting cause-effect relationships in highly complex flow systems, of the type that so often are involved in regional problems of water resource development and management.

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