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Harshbarger, John W. (13)Davis, Donald R. (10)Evans, Daniel D. (10)Bradley, Michael D. (9)Roefs, Theodore G. (8)Simpson, Eugene S. (7)Gum, Russell L. (6)Buras, Nathan (3)Qashu, Hasan K. (3)View MoreTypes
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Desalination by salt replacement and ultrafiltration.

Muller, Anthony B. (The University of Arizona., 1974)

The replacement of solutes in a saline solution by a replacer chemical across an osmotic membrane, and the subsequent removal of the chemical by virtue of its special removal characteristics, comprises salt replacement desalination. Any of a number of removal processes may be coupled to the replacement step, the process being determined by characteristics of the replacer. Ultrafiltration is examined as a removal process with sucrose as the replacer chemical. A theoretical treatment of osmotic flow across semipermeable membranes is presented in terms of phenomenological and first-order transport equations. The pore flow and solution-diffusion models of the transport kinetics of such osmotic flows are derived. An experimental examination of the ultrafiltration of sucrose shows that higher flux membranes operated at lower pressures than reverse osmosis offer comparable product fluxes. Such a system would, thus, not require the high-pressure apparatus required for reverse osmosis. Experimental results also show that a constant separation relationship exists between concentrate and permiate at operating pressures above the osmotic pressure of the retinate, and that the separation characteristics of membranes of different cutoff levels with solutes of molecular weight well below the cutoff level being filtered are similar. These findings indicate that salt replacement with ultrafiltration has strong possibilities for development as a large-scale desalination method.

Analysis of flow to pumping wells in a saline coastal aquifer, Puerto Peñasco, Sonora, Mexico

Dunn, Alison Leeds. (The University of Arizona., 1981)

A line of pumping wells, 100-175 m from the shore in a shallow coastal aquifer east of Puerto Petasco, Sonora, Mexico, supplied salt water at a rate of 7,500 to 11,500 m³/day to a shrimp aquaculture facility. This water exhibited salinities as high as 41.5 parts per thousand (ppt) and the well farthest inland yielded the most saline water. Effluent was discharged from the facility at an average rate of 6,000 m³/day to two lakes 400 m inland from the wells. In 1979, the salinity in the first lake ranged between 39 and 42 ppt and in the second lake between 41 and 78 ppt. Measurements of ground-water levels were made in nine smalldiameter well-points. A steady-state numerical model was used to simulate flow conditions in the study area and calibrated against these measurements on three separate dates. The best fit was obtained by modeling the effluent lakes as zones of semi-pervious leakage to the main aquifer and assuming a uniform transmissivity of 575 m²/day. Flow-net analyses indicated that 30 to 50 percent of the pumped water was contributed from the direction of the effluent lakes. The regional gradient could not be determined, and further research would be needed to identify its influence on the local flow regime.

Parameter identifiability of an erosion simulation model

Blau, Jeff Bryant,1957- (The University of Arizona., 1986)

An erosion simulation model based on the kinematic equations of flow and advective transport of sediment with rill and interrill source terms is written in a finite difference form. The accuracy of the numerical solution is examined using the analytical solutions to the model for some special cases. The parameter identifiability of the model is examined using contour plots of the objective function response surface. The erosion equation is non-dimensionalized to allow for the examination of all parameter combinations. Two optimization routines are used to identify parameters for theoretical, theoretical with added error, and observed sediment concentration data. The finite difference formulation used is a suitable numerical scheme for this type of erosion model. Parameter identifiability of this erosion model is difficult because of parameter insensitivity and parameter interactions for some cases. Both the numerical scheme and the random error have little effect on parameter identifiability.

Prefeasibility study of some drought alleviation measures in the Niger River Basin

Maiga, Housseini Amadou. (The University of Arizona., 1981)

The Niger River Basin is situated in a geographic area with a climate which imposes a long dry season each year and is particularly harsh on the vegetation cover due to greatly reduced moisture availability. Furthermore, the study area is struck by recurrent droughts having devastating effects. In addition to causing human suffering and animal death, the droughts have drastic impact on the hydrology of the river and the fragile environment, playing havoc with the underdeveloped economy of the basin countries. To alleviate these adverse effects, the present study attempts to examine, from a water resource manager's point of view, the experiences as well as the potential feasibility of some proposed drought-control measures. Control measures of emergency relief, water conservation and water supply are studied, including their legal, institutional, socio-economic and financial aspects in the Niger Basin. These measures integrated in a contingency plan should also be part of a long-term development strategy to enable the basin countries to better withstand the effects of future droughts by providing self-sufficiency in food production, rehabilitation of the environment, and economic development.

Computerized water distribution management for the Upper Pampanga River Project, Philippines

Aldovino, Lino Pineda,1945- (The University of Arizona., 1977)

This study is concerned with the development of a model for realtime water distribution management for rice crop production in the Upper Pampanga River Project (Philippines). The model utilizes a management technique which considers water distribution at the farm level on a system-wide basis under the constraints of the present users and the physical system situations. The intent of the project is to rely as much as possible on the available uncontrolled streamflows and rainfall during the wet season in order to minimize releases from the Pantabangan reservoir, and thus conserve most of the impounded water for irrigation during the dry season. A computerized model which incorporates a parameter prediction-correction technique is developed for calculating the daily water scheduling for the entire canal network of the UPRP. To determine how much water is needed, a daily water budget at each of the 2,216 rotation areas is performed in conjunction with the daily predicted uncontrolled streamflows, rainfall, varying water requirement, and water status at the farm level. Subsequent delivery correction schedules are determined based on the degree of the prediction error. Studies were conducted for the determination of the appropriate rainfall prediction scheme used in the scheduling model. Selection of the scheme was done through simulation of field operations at the farm level and by the application of the rainfall-use efficiency criterion. Time lags along the Pampanga River and the canal network were analyzed to determine the possibility of supplying the entire network from the Pantabangan Dam within 24 hours. The idealized solution of the problem of inequitable distribution of water within a rotation unit is also presented. The ability of the model to provide situation-and-user-oriented guidelines for water distribution activities is demonstrated.

Applications of Box-Jenkins methods of time series analysis to the reconstruction of drought from tree rings

Meko, David Michael. (The University of Arizona., 1981)

The lagged responses of tree-ring indices to annual climatic or hydrologic series are examined in this study. The objectives are to develop methods to analyze the lagged responses of individual tree-ring indices, and to improve upon conventional methods of adjusting for the lag in response in regression models to reconstruct annual climatic or hydrologic series. The proposed methods are described and applied to test data from Oregon and Southern California. Transfer-function modeling is used to estimate the dependence of the current ring on past years' climate and to select negative lags for reconstruction models. A linear system is assumed; the input is an annual climatic variable, and the output is a tree-ring index. The estimated impulse response function weights the importance of past and current years' climate on the current year's ring. The identified transfer function model indicates how many past years' rings are necessary to account for the effects of past years' climate. Autoregressive-moving-average (ARMA) modeling is used to screen out climatically insensitive tree-ring indices, and to estimate the lag in response to climate unmasked from the effects of autocorrelation in the tree-ring and climatic series. The climatic and tree-ring series are each prewhitened by ARMA models, and crosscorrelation between the ARMA residuals are estimated. The absence of significant crosscorrelations Implies low sensitivity. Significant crosscorrelations at lags other than zero indicate lag in response. This analysis can also aid in selecting positive lags for reconstruction models. An alternative reconstruction method that makes use of the ARMA residuals is also proposed. The basic concept is that random (uncorrelated in time) shocks of climate induce annual random shocks of tree growth, with autocorrelation in the tree-ring index resulting from inertia in the system. The steps in the method are (1) fit ARMA models to the tree-ring index and the climatic variable, (2) regress the ARMA residuals of the climatic variable on the ARMA residuals of the treering index, (3) substitute the long-term prewhitened tree-ring index into the regression equation to reconstruct the prewhitened climatic variable, and (4) build autocorrelation back into the reconstruction with the ARMA model originally fit to the climatic variable. The trial applications on test data from Oregon and Southern California showed that the lagged response of tree rings to climate varies greatly from site to site. Sensitive tree-ring series commonly depend significantly only on one past year's climate (regional rainfall index). Other series depend on three or more past years' climate. Comparison of reconstructions by conventional lagging of predictors with reconstructions by the random-shock method indicate that while the lagged models may reconstruct the amplitude of severe, long-lasting droughts better than the random-shock model, the random-shock model generally has a flatter frequency response. The random-shock model may therefore be more appropriate where the persistence structure is of prime interest. For the most sensitive series with small lag in response, the choice of reconstruction method makes little difference in properties of the reconstruction. The greatest divergence is for series whose impulse response weights from the transfer function analysis do not die off rapidly with time.

Strategies to improve water management in Mexican irrigation districts : a case study in Sonora

Palacios Vélez, Enrique,1933- (The University of Arizona., 1976)

Few studies have been made regarding the efficiency of water use in irrigation systems in operation. Therefore, in this work the search for methodologies to evaluate the actual efficiency of water use in a Mexican irrigation district as well as methods which may improve this efficiency is emphasized. The work has been divided into four parts. In the first part, the analysis of the economic activities in the irrigation district by means of linear programming has permitted finding the marginal productivity of water which is used as a shadow price for economic evaluation of the operating rules. In this part a relationship between the marginal productivity of water and the conveyance efficiency has also been found. In the second part, using hydrological historical data and a pattern of monthly water demand for crops obtained in the first part, control curves of the reservoir levels which permit knowledge of the probability of risk of spill and shortage were computed. Utilizing these curves and a simple linear programming model for finding the optimal economic annual average release, operating rules for the reservoir have been deduced. These rules were tested by means of a simulation model and their economic effectiveness was estimated using a benefit-cost analysis, showing a significant improvement in benefits for the farmers as a consequence of using these rules. In the third part, the conveyance losses in the canal network are analyzed using a linear regression between releases and deliveries. The proposed model permits an estimation of the conveyance efficiency and its division into two component factors, the intrinsic efficiency directly related to the physical characteristics of the canals, and the operational efficiency related to water management in the canal network. Knowing these components, it is possible to classify the conveyance losses as well as deduce operating rules for improving the operational efficiency. In making decisions about the methods to be used for improving the conveyance efficiency, benefits and costs must be taken into account. Therefore, a practical relationship for evaluating the economic feasibility of lining canals, considering those benefits and costs, is found as well as a method for economic evaluation of the operating rules. Finally, in the last part of this work, a practical methodology for estimating the application efficiency at the farm level in an irrigation district and small divisions as well is shown. This method is useful in finding where the problems in water use are more important within the district and which could be their principal causes. Utilizing data from experiments, which are available in most of the Mexican irrigation districts, production functions relating yields of crops to the amount of water applied and the percentage of moisture depletion in the soil before and during the flowering season of the crop, have been found. These functions can be used not only for obtaining the optimal economic depth of water to be applied and irrigation timing but also for deriving the optimal water use efficiency, whi6h, when related to actual values of this water efficiency in each subdivision of the district, permits the deduction of a practical water use efficiency index which is useful for detecting where the problems in water use are and what are the potential returns for the farmers in each of the considered subdivisions.

Coupling stochastic and deterministic hydrologic models for decision-making

Mills, W. C.(William Carlisle) (The University of Arizona., 1979)

Many planning decisions related to the land phase of the hydrologic cycle involve uncertainty due to stochasticity of rainfall inputs and uncertainty in state and knowledge of hydrologic processes. Consideration of this uncertainty in planning requires quantification in the form of probability distributions. Needed probability distributions, for many cases, must be obtained by transforming distributions of rainfall input and hydrologic state through deterministic models of hydrologic processes. Probability generating functions are used to derive a recursive technique that provides the necessary probability transformation for situations where the hydrologic output of interest is the cumulative effect of a random number of stochastic inputs. The derived recursive technique is observed to be quite accurate from a comparison of probability distributions obtained independently by the recursive technique and an exact analytic method for a simple problem that can be solved with the analytic method. The assumption of Poisson occurrence of rainfall events, which is inherent in derivation of the recursive technique, is examined and found reasonable for practical application. Application of the derived technique is demonstrated on two important hydrology-related problems. It is first demonstrated for computing probability distributions of annual direct runoff from a watershed using the USDA Soil Conservation Service (SCS) direct runoff model and stochastic models for rainfall event depth and watershed state. The technique is also demonstrated for obtaining probability distributions of annual sediment yield. For this demonstration, the deterministic transform model consists of a parametric event-based sediment yield model and the SCS models for direct runoff volume and peak flow rate. The stochastic rainfall model consists of a marginal Weibull distribution for rainfall event duration and a conditional log-normal distribution for rainfall event depth given duration. The stochastic state model is the same as employed for the direct runoff application. Probability distributions obtained with the recursive technique for both the direct runoff and sediment yield demonstration examples appear to be reasonable when compared to available data. It is therefore concluded that the recursive technique, derived from probability generating functions, is a feasible transform method that can be useful for coupling stochastic models of rainfall input and state to deterministic models of hydrologic processes to obtain probability distributions of outputs where these outputs are cumulative effects of random numbers of stochastic inputs.

Assessing impacts of dropping water table in Casa Grande Ruins National Monument

VanPelt, Derek. (The University of Arizona., 1998)

A water resources assessment of the Casa Grande Ruins National Monument (CAGR) was conducted using historical and recent data. The data were sorted and analyzed to determine whether the monument grounds have the potential for subsidence, and in particular, differential subsidence. Further research was conducted to ascertain the cause of the loss of the mesquite woodland on the monument grounds in the 1940's. To determine the potential for subsidence at the monument, a subsidence model was constructed based on geology developed from well logs of local wells. The model allowed the water table to fall from the predevelopment level to the present, and to possible future levels. The region of the Casa Grande Ruins National Monument has the potential for subsidence and differential subsidence on a geological basis, should the water table drop sufficiently. The majority of the mesquites on the monument grounds died in the 1940's. This has been attributed to groundwater pumping that lowered the groundwater table, but may also have been caused by drought, loss of a perched aquifer, disruption of overland flow by construction around monument grounds, and construction of the contour dykes at CAGR.

Operation plan of the Wonogiri Reservoir, Central Java, Indonesia

Sutadi, Graita. (The University of Arizona., 1982)

The feasibility study estimated that the Wonogiri Reservoir will be able to supply water with a 90 percent reliability. This estimation was supplied by frequency analysis. Twenty years of monthly streamflow data of the Solo River were used in these calculations. The current study estimates a 5.82 percent probability of failures, which is provided by water balance calculations. The streamflow data are extended by the first-order autoregressive (Markov) model. The generated streamflows are multiplied by a runoff factor. The feasibility study specified that a flood having 4,000 cms peak with the March-1966 flood standard hydrograph can be effectively reduced to 400 cms by the reservoir, where the water level will reach an elevation of 137.7 meters. The current study researches the reservoir's flood control ability by reservoir routing. Assuming the water level reaching 138.2 meters the reservoir can reduce a flood of 4,400 cms peak.

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