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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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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.

The effects of molecular diffusion on groundwater solute transport through fractured tuff

Walter, Gary R. (The University of Arizona., 1985)

Theoretical and experimental studies of the chemical and physical factors which affect molecular diffusion of dissolved substances from fractures into a tuffaceous rock matrix have been made on rocks from G Tunnel and Yucca Mountain at the Nevada Test Site (NT8). Although a number of physical/chemical processes may cause nonadvective transport of dissolved species from fractures into the tuff matrix, diffusion in these rocks is controlled by the composition of the groundwater through multicomponent effects and several rock properties. The effective molecular diffusion coefficient of a particular species in the tuff can be related to its free aqueous diffusion coefficient by Dₑ = θ(m)(α/τ²)D₀ where bm is matrix porosity, α is the constrictivity, and τ is the tortuosity. The porosities of the samples studied ranged from 0.1 to 0.4. The parameter (α/τ²) ranged from 0.1 to 0.3, and effective matrix dif— fusion coefficients were measured to be between 2 to 17. x 10⁻⁷ cm²/s for sodium halides and sodium pentafluorobenzoate. Total porosity was found to be the principle factor accounting for the variation in effective diffusion coefficients. The constrictivity— tortuosity factor was found to have a fair correlation with the median pore diameters measured by mercury intrusion. Measurements of bulk rock electrical impedance changes with frequency indicate that the constrictivity factor, a, has a maximum value of 0.8 to 1, but may be smaller. If the larger values are correct, then the diffusion paths in tuff are more tortuous than in granular media. The diffusion coefficient matrix computed for various tracers in J-13 well water from the NTS indicates coupling of the diffusion fluxes of all ionic species. Multicomponent diffusion is a second order effect, however, which does not significantly affect experimental results. The results of a bench—scale fracture flow experiment revealed that the transport of ionic tracers (SCN ⁻ and pentafluorobenzoate) was affected by diffusion into the tuff matrix. The transport of a particulate tracer did not appear to be affected by diffusion.

Flow recession in the ephemeral stream

Peebles, Roger W. (The University of Arizona., 1975)

The recession portion of the ephemeral stream hydrograph is modeled as a conceptual analog of the discharge from a single leaky reservoir. Physically, the reservoir may be considered to approximate that portion of the ephemeral stream channel that is flowing at the beginning of recession. The discharging reservoir is described by a continuity equation and by discharge-stage and storage-stage relations. No input is routed through the reservoir. It is assumed that initially (at the beginning of recession) the reservoir has water in storage. The discharge-stage relation for the reservoir is defined by the rating curve for the stream and storage-stage depends on reservoir configuration. A good agreement between observed and model curves is obtained by optimizing two parameters, reservoir leakage rate and initial storage, The agreement is most sensitive to changes in initial storage. Best parameter values are physically realistic and best reservoir configuration has leakage that varies directly with stage (depth) and storage that varies as the square of stage.

A distributed surface temperature and energy balance model of a semi-arid watershed.

Washburne, James Clarke. (The University of Arizona., 1994)

A simple model of surface and sub-surface soil temperature was developed at the watershed scale (-100 km²) in a semi-arid rangeland environment. The model consisted of a linear combination of air temperature and net radiation and assumed: (1) topography controls the spatial distribution of net radiation, (2) near-surface air temperature and incoming solar radiation are relatively homogeneous at the watershed scale and are available from ground stations and (3) soil moisture dominates transient soil thermal property variability. Multiplicative constants were defined to account for clear sky diffuse radiation, soil thermal inertia, an initially fixed ratio between soil heat flux and net radiation and exponential attenuation of solar radiation through a partial canopy. The surface temperature can optionally be adjusted for temperature and emissivity differences between mixed bare soil and vegetation canopies. Model development stressed physical simplicity and commonly available spatial and temporal data sets. Slowly varying surface characteristics, such as albedo, vegetation density and topography were derived from a series of Landsat TM images and a 7.5" USGS digital elevation model at a spatial resolution of 30 m. Diurnally variable atmospheric parameters were derived from a pair of ground meteorological stations using 30-60 min averages. One site was used to drive the model, the other served as a control to estimate model error. Data collected as part of the Monsoon '90 and WG '92 field experiments over the ARS Walnut Gulch Experimental Watershed in SE Arizona were used to validate and test the model. Point, transect and spatially distributed values of modeled surface temperature were compared with synchronous ground, aircraft and satellite thermal measurements. There was little difference between ground and aircraft measurements of surface reflectance and temperature which makes aircraft transects the preferred method to "ground truth" satellite observations. Mid-morning modeled surface temperatures were within 2° C of observed values at all but satellite scales, where atmospheric water vapor corrections complicate the determination of accurate temperatures. The utility of satellite thermal measurements and models to study various ground phenomena (e.g. soil thermal inertia and surface energy balance) were investigated. Soil moisture anomalies were detectable, but were more likely associated with average near-surface soil moisture levels than individual storm footprints.

Remote and in situ measurements of soil and vegetation water content

Harlow, Robert C. (The University of Arizona., 2003)

Accurate estimates of soil moisture are necessary to predict evapotranspiration, runoff, infiltration, and groundwater recharge and, through these variables, weather, climate, and fire and flood frequencies. This dissertation is motivated by the need to estimate soil water content from remotely sensed passive microwave emission. Two different approaches are taken: (1) improved modeling of the microwave emission from the land surface; and (2) measurements of the average dielectric properties of the soil media and vegetation canopies. Consequently, the first part of the dissertation describes how a stratified dielectric model of the microwave emission from the soil was extended to take into account the effects of vegetation. The model parameters were calibrated using observed data and a robust optimization routine. However, the availability of measurements of some of these parameters, particularly the profile of dielectric permittivity of the canopy, would facilitate a more complete evaluation of the accuracy of the extended microwave emission model. The second part of this dissertation describes progress towards the development of a technique to measure the dielectric of vegetation canopies. This technique is based on gated time domain transmission measurements through the substance of interest. Preliminary studies carried out using soils with varying salinity and water content and vegetation show (1) an unexpected response of the signal to saline soils, and (2) a possible dielectric signature of the onset of stress in plant stems.

Remote-Sensing Soil Moisture Using Four-Dimensional Data Assimilation.

Houser, Paul Raymond,1970- (The University of Arizona., 1996)

The feasibility of synthesizing distributed fields of remotely-sensed soil moisture by the novel application of four-dimensional data assimilation applied in a hydrological model was explored in this study. Six Push Broom Microwave Radiometer images gathered over Walnut Gulch, Arizona were assimilated into the TOPLATS hydrological model. Several alternative assimilation procedures were implemented, including a method that adjusted the statistics of the modeled field to match those in the remotely sensed image, and the more sophisticated, traditional methods of statistical interpolation and Newtonian nudging. The high observation density characteristic of remotely-sensed imagery poses a massive computational burden when used with statistical interpolation, necessitating observation reduction through subsampling or averaging. For Newtonian nudging, the high observation density compromises the conventional weighting assumptions, requiring modified weighting procedures. Remotely-sensed soil moisture images were found to contain horizontal correlations that change with time and have length scales of several tens of kilometers, presumably because they are dependent on antecedent precipitation patterns. Such correlation therefore has a horizontal length scale beyond the remotely sensed region that approaches or exceeds the catchment scale. This suggests that remotely-sensed information can be advected beyond the image area and across the whole catchment. The remotely-sensed data was available for a short period providing limited opportunity to investigate the effectiveness of surface-subsurface coupling provided by alternative assimilation procedures. Surface observations were advected into the subsurface using incomplete knowledge of the surface-subsurface correlation measured at only 2 sites. It is perceived that improved vertical correlation specification will be a need for optimal soil moisture assimilation. Based on direct measurement comparisons and the plausibility of synthetic soil moisture patterns, Newtonian nudging assimilation procedures were preferred because they preserved the observed patterns within the sampled region, while also calculating plausible patterns in unmeasured regions. Statistical interpolation reduced to the trivial limit of direct data insertion in the sampled region and gave less plausible patterns outside this region. Matching the statistics of the modeled fields to those observed provided plausible patterns, but the observed patterns within sampled area were largely lost.

Thermodynamic and isotopic systematics of chromium chemistry

Ball, James William,1945- (The University of Arizona., 1996)

This investigation has produced four major results: (1) Thermodynamic properties of chromium metal, aqueous ions, hydrolysis species, oxides and hydroxides were compiled. Data were critically evaluated, some data were recalculated, and thermodynamic properties were selected. (2) A method was developed for separating chromium from its natural water matrix using sequential anion and cation exchange chromatography. (3) A method for determining the ⁵³Cr/⁵²Cr ratio using solid-source thermal ionization mass spectrometry with the silica gel-boric acid ionization- - enhancement technique was developed. (4) Ground water samples from six locations were analyzed for their ⁵³Cr/⁵²Cr ratio using the above methods. Results from carefully measured electromotive force (emf) values for the reduction of Cr³⁺ to Cr²⁺ were recalculated for compatibility with the infinite dilution standard state, and a revised ∆G°(f) for Cr²⁺(aq) was calculated. Equilibrium constants for chromium(III) hydrolysis were taken from Rai, et al. (1987) and for chromium(VI) hydrolysis from Palmer, et al. (1987). The ion exchange method is based on retention of chromium(VI) on strongly basic anion exchange resin at pf1 4 and its reductive elution with 2N HNO₃ . Chromium(III) is retained on strongly acidic cation exchange resin at pH 1.3 and eluted with 5N HNO₃. Possible interferents include metals that form both oxyanions and cations. High-purity reagents and containers made of rigorously cleanable noncontaminating materials are required. Samples for mass spectrometry are pretreated with aqua regia and concentrated nitric acid, then mixed with silica and boric acid and transferred to the tantalum filament of a stainless steel and glass sample holder. The ⁵³Cr/⁵²Cr ratio was measured to avoid isobaric interferences with iron. To be significantly different from each other, isotopic signatures must differ by at least 0.5 per mil. Samples from six locations were examined for their ⁵³Cr/⁵²Cr ratio. For the samples with natural origin, the spread in δ⁵³Cr values of-2.0 to +3.0 per mil suggests that samples of chromium derived from differing source materials or from different geographic locations have distinct isotopic signatures. Conclusions regarding source-related variations in the isotopic signature of contaminant chromium are problematic, because specific information about the respective source materials is lacking.

Steps towards the implementation of ERT for monitoring of transient hydrological processes

Furman, Alexander (The University of Arizona., 2003)

The adaptation of the electrical resistivity tomography (ERT) for monitoring of subsurface hydrological processes is the focus of this research. Specifically, the increase in the method's accuracy, expressed by its spatial and temporal resolution, is sought. A spatial sensitivity analysis of the ERT method is presented. This sensitivity analysis is conducted by a perturbation approach, and is making extensive use of the analytic element method (AEM) to compute potentials in the subsurface. Presented are sensitivity maps for individual typical and atypical arrays. Also presented are sensitivity maps for surveys comprised of a single array type and for mixed surveys, and guidelines for array selection for the detection of a localized target. Results indicate superiority of wide arrays over small arrays, and the relatively poor performance of the double dipole array type. Several optimality criteria are discussed for the selection of an optimal survey, including optimality of individual arrays to individual subsurface targets (locally optimal), and global optimality, achieved through the use of genetic algorithms. In both cases results show superiority of mixed surveys. The method presented here, for optimal ERT configuration, opens the way for implementation of the method for a wide variety of hydrological applications. In addition to the main focus of this dissertation, a complementary work was completed to extend the AEM to compute transient processes. This unique solution uses the Laplace transform to bring the flow equation to a linear, time independent form. The resultant modified Helmholtz equation is then solved using the AEM, and the result is numerically transformed to the time domain.

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