RSS 1.0Hydrology and Water Resources in Arizona and the Southwest, Volume 06 (1976)
ABOUT THE COLLECTION
Proceedings of the Hydrology section of the Annual Meeting of the Arizona-Nevada Academy of Science. Full text manuscripts of work presented. Research related to water resources, water management, and hydrologic studies primarily focused regionally on southwestern US.
Volume 6. Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science.
April 29-May 1, 1976, Tucson, Arizona
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Recent Submissions
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Hydrology and Water Resources in Arizona and the Southwest, Volume 6 (1976)Arizona-Nevada Academy of Science, 1976-05-01
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Windbreaks May Increase Water Yield from the Grassland Islands in Arizona's Mixed Conifer ForestsThe general hydrologic characteristics, selected climatic factors, and soil properties of the high-elevation grasslands are compared to the surrounding forest. Evidence shows that water yield could be increased by 1-1/2 to 2 inches if snow could be held where it falls. It may be possible to establish tree windbreaks in the grassland by altering the microclimate during establishment, and introducing mycorrhiza with the planted seedlings. This conclusion is supported by good survival in a 2-year planting trial.
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Feasibility of Using Solar Energy for Irrigation PumpingSolar powered pumping is technically feasible. However, solar energy intensity is variable and its collection requires high capital investment. Present production methods might require modification for most economic use of solar energy. Various irrigation and pumping practices are examined to determine those most compatible with use of solar power. The tentative conclusion of the study is that solar energy usage is most economical for driving pumps only during sunlight hours and where pumping requirements are uniform throughout the year. Solar energy is a more costly source of pumping power than electricity or natural gas.
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Mathematical Modelling of a Forward Osmosis ExtractorOsmosis occurs when two solutions of differing osmolar concentrations are separated by a membrane permeable to the solvent but not (or nearly not) to the solutes. This paper derives the relationship between the kinetics and design parameters of systems designed for the purpose of applying this process to problems such as agricultural water reclamation, dehydration of solutions and the production of potable nutrient solutions from sea water. Three mathematical models that include increasingly complex fundamental process assumptions are presented. In all cases the fundamental mechanical device is assumed to be a continuous flow extractor that incorporates a semipermeable membrane.
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Optimal Livestock Production of Rehabilitated Mine LandsStrip mining leaves behind spoils to be recontoured to maximize the benefit of livestock production on the rehabilitated land. This paper designs watersheds to achieve a balance between two main range livestock requirements, forage and stock water by way of grading and furrowing man-made slopes. The three design attributes, surface configuration, surface treatment, and range management policy are optimized with respect to maximal profit accounting for natural uncertainties in 3 variables, viz., time interval between storm arrivals, precipitation per storm event, and duration of the storm event. Runoff and sedimentation are modeled on an event basis as functions of said random variables. The stock water reservoir at the bottom of the watershed is dredged periodically. The stochastic model is applied to the Black Mesa in Northern Arizona which is in the process of being strip-mined for coal.
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On the Modeling and Computational Aspects of Dynamic Programming with Applications in Reservoir ControlA discrete stochastic multistage decision model is developed, in the framework of which the dynamic programming algorithm is defined. It is demonstrated that the algorithm may be used as a solution procedure for non-routine reservoir control problems. The study demonstrates that analytical considerations may be used to significantly reduce the amount of computation needed for the implementation of the algorithm. Two reservoir control problems are studied: The "reliability problem" in which one seeks a minimum-cost operation rule under a constraint which specifies the maximum probability of shortage allowed during the life-time of the project, and the "range problem" in which the objective is the minimization of the expected value of the range of fluctuation around a critical storage level.
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A Method for Maximizing the Present Value of a Groundwater ResourceIn the past, researchers have applied a variety of analytical techniques for maximizing the present value of net benefits derived from a stock resource-simulation, calculus of variations, stochastic dynamic programming, and optimal control theory. This paper presents a more operational approach - linear programming. Applying linear programming to this type of problem requires a set of internal accounting constraints that prevent the additivity assumption of linear programming from being violated. A simplified, broadly drawn example from Southwest agriculture is used for demonstrating the model's structure and output.
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A Multiobjective Approach to Managing a Southern Arizona WatershedThe case study of an Upper San Pedro River watershed is developed to show how a multiple objective approach to decision-making may be used in watershed management. The effects of various land treatments and management practices on water runoff, sediment, recreation,, wildlife levels, and commercial potential of a study area are investigated while observing constraints' on available land and capital. The example involves the optimization of five objective functions subject to eighteen constraints. In an iterative manner, the decision-maker proceeds from one noninferior solution to another, comparing sets of land management activities for reaching specified goals, and evaluating trade-offs between individual objective functions. This technique, which involves the formulation of a surrogate objective function and the use of the cutting plane method to solve the general nonlinear problem, hopefully provides a compromise between oversimplified and computationally intractable approaches to multiobjective watershed management.
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Construction, Calibration and Operation of a Monolith Weighing LysimeterConstruction of a hydraulic monolith weighing lysimeter was undertaken, however, due to inherent design and/or construction errors this proved to be an inadequate device for the accurate determination of evapotranspiration from Larrea divaricatta (creosote bush). Prior inability to stabilize the lysimeter with respect to barometric and temperature fluctuations, and eventual failure within the hydraulic transducer package led to the eventual abandonment of the hydraulic load cell design, and adoption of an electronic strain gage transducer package. This paper deals with the detailed design and construction phases of the original lysimeter, the inherent difficulties encountered, and with the modification and conversion of the lysimeter to the electronic transducer assembly. Accompanying test data with respect to sensitivity, response time and differential loading characteristics support the premise that the electronic load cell design has inherent maintenance and operational advantages over the hydraulic transducer lysimeter.
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Resolutions of Analog Rainfall Records Relative to Chart ScalesFive rainfall distributions, four l-in rainfall depths and one 3-in rainfall depth were plotted on charts with five different combinations of time and depth scales. The plotted events were read on an analog-to-digital converter by four different researchers. Each reading of a plotted record was compared with the known simulated rainfall-rate distribution. The correspondence of the rainfall rates read from the charts with the actual rainfall rate distribution is measured by an integral squared error and correlation coefficient. The results showed a general correspondence between error and the chart scale and a strong influence of maximum recorded rate and rate distribution on the error. For the chart scales evaluated, error did not become more directly associated with scale, except when recorded rates were less than about 10 in/hr. Error was directly related to the number of points read in any given trace by the relation E = 16.3N^(-0•426).
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Evaluation of Recharge Through Soils in a Mountain Region: A Case Study on the Empire and the Sonoita BasinsA conventional water balance method, employing long-term average values of rainfall, runoff and evapotranspiration yields near-zero recharge values for the Empire and the Sonoita basins. These results, however, are not in agreement with those obtained from an analysis of the local ground water regimes. A different approach for calculating recharge, based on the typical characteristics of these arid basins, is proposed. In particular, both basins are characterized by intense thunderstorms of short duration in the summer which occur usually towards the evening, and shallow, sandy-gravelly soils with a relatively high permeability overlying fractured rocks in the elevated mountain regions. These factors may cause a considerable amount of water to infiltrate through the soil profile, thereby escaping evapotranspiration during the following day. The proposed model deals with separate thunderstorm events using mean values of rainfall intensity and frequency corresponding to elevation. This model was coupled with a numerical solution of the flow equation which was used to solve the one dimensional water flow through a soil profile. The solution includes sink terms and was solved for the simultaneous processes of infiltration, moisture redistribution and evapotranspiration. The results obtained show almost no recharge in the low valleys, but significant recharge in the mountains. The amount of recharge increases with elevation and decreases with the depth of the soil profile.
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Application of Carbon-14 Ground-Water Ages in Calibrating a Flow Model of the Tucson Basin Aquifer, ArizonaIn the absence of pure piston flow, the carbon-14 ages of ground-water can be related to groundwater residence times only in the context of a flow model. To do this, a three-dimensional digital computer model of a portion of the Tucson Basin Aquifer was constructed using the theory of finite-state mixing cell models. The model was calibrated against the spatial distribution of adjusted carbon-14 ground-water ages, and once a reasonable fit was obtained, the ground-water residence times were calculated. The model also provides a first approximation to three-dimensional flow in the aquifer as well as an estimate of the long-term average annual recharge to the aquifer.
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Chlorofluorocarbons as Hydrologic Tracers, A New TechnologyThe nationwide research undertaken to study environmentally dispersed chlorofluorocarbons introduced into the atmosphere from aerosol cans and refrigeration systems has indicated that these compounds are potentially ideal hydrologic tracers, especially Freon-11 (Cl₃CF). The major advantages of Cl₃CF as a tracer are its non-polluting conservative nature, extremely low toxicity and sorptivity on clays, quantifiable build-up in the atmosphere, and a detection limit of about 10⁻¹⁴ grams. Quick and inexpensive detection of Cl₃CF can be done using a field-operable gas chromatograph with a pulsed electron-capture detector system. The presence of Cl₃CF in ground water, indicating an age of less than 30 years, will permit delineation of recent recharge areas. The absolute age of the recharging water is proportional to the atmospheric concentration of Cl₃CF at the time of recharge. The simple quantifiable increase of Cl₃CF in the atmosphere should therefore yield more accurate ages than those determined by tritium analysis.
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An Energy Budget Analysis of Evapotranspiration from SaltcedarEnergy budget evaluations of evapotranspiration from saltcedar were carried out on the flood plain of the Rio Grande River, near Bernardo, New Mexico. The site was adjacent to the Bureau of Reclamation's lysimeter study of water use by saltcedar. The energy budget for the cloudless day of June 14, 1975, revealed that energy gains from net radiation totaled 432 cal/cm² , while energy losses (in cal/cm2 ), were 14 to stored energy, 31 to convection, and 387 to evapotranspiration (ET). The energy loss to ET is equivalent to the latent energy contained in about 6.5 mm of water. The energy budget values are reasonable for a phreatophyte community in a semi-arid environment. The latent energy loss compares favorably with 401 cal/cm² measured by three lysimeters, although there were discrepancies in timing and amounts of loss among the individual lysimeters. The mean canopy diffusion resistance was 1.90 sec/cm over a 10-hour daytime period on June 14. The mean resistance was combined with vapor pressure deficit to predict lysimeter ET on three subsequent days. The agreement was within 12 percent, which suggests that diffusion resistance may be useful for simple ET predictions.
