• Politics and the Colorado River

      Steiner, Wesley E.; Arizona Water Commission, Phoenix, Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      The Colorado River is the only major stream in the U.S. whose water supply is fully utilized. This distinction has brought the Colorado more than its share of controversy, within states, between states and between nations. The Colorado River compact, whose purpose was to equitably apportion the waters between the upper and lower basins and to provide protection for the upper basin through water reservation, was ratified by all states except Arizona, in 1923. Arizona finally ratified it in 1944. The history of controversies and negotiation concerning the compact are outlined through the supreme court decision on march 9, 1964, which entitled California to 4.4 maf, Nevada to 0.3 maf and Arizona to 2.8 maf, of the first 7.5 maf available in the lower Colorado. Unfortunately, the court did not attempt to establish priorities in the event of shortage. The problem is complicated by an international treaty of 1944, guaranteeing Mexico 1.5 maf annually, except in years of unusual circumstances. Because Senator Connally of Texas was then chairman of the senate foreign relations committee and because the treaty allocated twice as much Colorado River water to Mexico as it was then using, it was argued that this treaty represented a tradeoff to Mexico, giving it less water from the Rio Grande in exchange for more water from the overburdened Colorado. Problems of inter-basin water transfer studies, uniform Colorado basin water quality standards and central Arizona project planning are discussed.
    • Augmenting Annual Runoff Records Using Tree-Ring Data

      Stockton, Charles W.; Fritts, Harold C.; Laboratory of Tree-Ring Research, The University of Arizona, Tucson, Arizona, 85721 (Arizona-Nevada Academy of Science, 1971-04-23)
      Statistical analyses of existing hydrologic records suffer from the problem that such records are of relatively short duration, and therefore may not necessarily be random samples of the infinite population of events. On the hypothesis that tree-ring series and runoff series respond to a common climatic signal or signals that permit prediction of annual runoff from annual ring-width index, tree-ring data are used to extend available runoff records backwards in time to permit more accurate estimates of the 3 most common statistics used in hydrology: the mean, the variance and the 1st order correlation. It is assumed that both series are generated by the climatic parameters of precipitation, temperature, evapotranspiration, seasonal regime and spatial distribution. Of major concern in the reconstruction of annual runoff series from tree-ring records was the difference in persistence within each of the 2 series. A matrix of the tree-ring data was constructed, lagged up to 3 times and principal components were extracted. The covariation in this matrix was then decomposed by extracting the Eigen-vectors, and multiple regression was then used to weight the respective series and the differences in persistence were determined. This method was applied to watersheds of diverse characteristics and improved estimates of the mean and variance were obtained.
    • Seasonal Effects on Soil Drying After Irrigation

      Kimball, B. A.; Jackson, R. D.; U.S. Water Conservation Laboratory, Soil and Water Conservation Research Division, Agricultural Research Service, U.S. Department of Agriculture, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1971-04-23)
      A study was made to determine how the evaporation rate from a bare Adelanto loam soil in Phoenix changes with season and with time since the last irrigation. The evaporation rates were determined by precision lysimeters in a bare field, with measurements being taken in every month of the year for at least a week after irrigation. The data exhibited a cosine-shaped curve, with a maximum evaporation rate of about 5 mm/day in summer and a minimum rate of about 2 mm/day in winter. By the seventh day, seasonal effects virtually disappear, and the evaporation rate is the same in both summer and winter, being about 2 mm/day after the 7th day and about 0.75 mm/day after the 21st day. It is generally accepted that soil dries in 3 stages, and the transition between the 1st and 2nd stages occurs when atmospheric conditions are no longer critical. In previous laboratory studies of soil drying, with constant atmospheric conditions, stage 1 was easily distinguished from stage II, and these results correlated closely with the equations of Gardner and Hillel. The individual drying curves of this field study were qualitatively different from the laboratory studies and did not confirm the predictions of the equations, suggesting that diurnal variations in temperature and other meteorological parameters have caused the difference.
    • Sulfuric Acid: Its Potential for Improving Irrigation Water Quality

      Bohn, H. L.; Westerman, R. L.; Department of Agricultural Chemistry and Soils, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1971-04-23)
      The 2 major environmental problems of Arizona and the southwest are the alkalinization of soil and water by irrigation and air pollution from copper smelting. It is proposed that the amelioration of both problems may be solved through a common process. This is the production of sulfuric acid from sulfur dioxide, which is the main pollutant of smelter effluent gases. The conversion process is cheap and easy, and the sulfuric acid could then be added to irrigation waters to increase the solubility of CA carbonate in the soil, thereby decreasing alkalinity. Lower alkalinity results in increased soil permeability and increased water use efficiency by plants. The potential market for sulfuric acid in irrigation was calculated, on the basis of neutralizing 90% of the bicarbonate ion concentration in Colorado River water and Arizona well water, to be about 1.6 million tons annually, representing about 1/3 of the sulfur now dissipated by smelters as air pollution. This market includes both the Imperial Valley of California and the Mexicali Valley of Mexico, both of which are currently experiencing mounting salinity problems. Salinity itself is not amenable to this treatment, but the cumulative increase in NA and bicarbonate may be slowed and reversed, leading to gradual soil stabilization.
    • Collective Utility: A Systems Approach for the Utilization of Water Resources

      Dupnick, Edwin; Duckstein, Lucien; Systems Engineering Department, University of Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      In the semiarid southwestern U.S. where competition for water is fierce between competing users, no regional agency controls water allocation, and as a result, much court litigation ensues. This paper attempts to develop a model for optimal allocation of water resources and to apply the model to a specific case study. In November 1969, the largest farming interest in the Sahuarita-continental area near Tucson filed a court suit seeking first to reduce the amount of groundwater used by 4 nearby copper mines, and then to allocate the water more evenly among various interests in the area. The farming interest maintained that the mines' drawdown on the groundwater table would soon deplete the supply to the point where agriculture would become impossible. The model utilizes the concept of collective utility which postulates the existence of an economic decision maker (edp). To get around the problem of determination of net revenue functions, the theory compares the relative desirability of neighboring economic states. The edp has the power to impose groundwater-use taxes in such a way as to maximize overall growth of collective utility in the Sahuarita-continental area, taking into account the externalities of the resource consumption. The mathematical analysis is presented in detail.
    • A Stochastic Analysis of Flows on Rillitto Creek

      Baran, N. E.; Kisiel, C. C.; Duckstein, L.; Hydrology & Water Resources, University of Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      In order to construct a simulation model for ephemeral streamflow and to examine in depth the problem of the worth of data for that model, measurements of the ephemeral streamflow of Rillitto creek, Tucson, were analyzed for the period 1933-1965. The simulation model was based on several hypotheses: (1) flow durations and their succeeding dry periods (time when no flow is present) are independent; (2) the distribution of the lengths of the dry periods and flows is stationary over a certain period of the year (summer); (3) stationary probability distributions for flow durations and for dry period lengths can be derived. A related problem was how to derive a simulation model for the total amount of flow (in acre-ft) within 1 flow period. Three variables were considered: flow duration (minutes), peak intensity of flow (cu ft/sec) and antecedent dry period-minutes (ADP). Because the assumption of variance constancy does not hold, a multiplicative regression model was used. Using an analysis of variance, which is described in detail, the worth of the 3 kinds of data were examined in relation to total flow. It was concluded that there are at least 5 times during the year when the flow intervals differ significantly, and the ADP is not important in determining flow volume because of the poison flow arrival rate in summer. Events occur at random and are not clustered as in summer, indicating that channel moisture does not differ much between flow events.
    • Optimal Utilization of Playa Lake Water in Irrigation

      Dvoracek, M. J.; Roefs, T. G.; Hydrology & Water Resources, University of Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      Playa lakes usually occur in arid or semiarid regions where lands are flat and there is an absence of well-developed surface drainage nets. They are usually filled by surface runoff from highly erratic precipitation patterns. There are about 20,000 of them in the high plains of Texas and their volume of storage is an estimated 2.5-3 maf. As such, they represent a major underutilized water source. The major drawbacks to their utilization are high evaporation losses, questionable depth-area relations and the stochastic nature of the rainfall source. This paper assumes that the water is available and presents a dynamic programming model useful in determining the optimal utilization of the water for irrigation. If irrigation is the major use, its timing of application is of paramount importance. A deterministic dynamic programming model, utilizing the state variables of antecedent soil moisture and amount of available water, is presented, and provides the time and amount of irrigation required to maximize crop response. A better stochastic model is also presented which considers rainfall probability and resulting lake filling. The models are only first attempts and do not incorporate all possible variables.
    • Regional Differences in Runoff-Producing Thunderstorms Rainfall in the Southwest

      Osborn, H. B.; Southwest Watershed Research Center, Tucson, Arizona, 85705 (Arizona-Nevada Academy of Science, 1971-04-23)
      Quantitative descriptions of regional differences of rainfall amounts and intensities in the southwest, such as depth-duration frequencies, generally have ignored differences in the storm system that generated the rainfall and have lumped essentially different storm systems together. Thunderstorm rainfall in southern Arizona and New Mexico were analyzed using data from both recording and standard rain gages. The results were somewhat conflicting. Possibly because of more frontal activity and less distance from the Gulf of Mexico., the thunderstorms in eastern New Mexico can be more intense than those in southeastern Arizona. Recording rain gage records suggest that air-mass thunderstorms produce a larger number of more intense short-duration (about 1 hour or less) rains in southeastern Arizona than in other parts of southern Arizona. However, standard rain gage records from southern Arizona indicate that rainfall from individual air-mass thunderstorms may be greater in south-central Arizona than in se or sw Arizona. But frequency analysis of standard gage data from air-mass storms shows that the 100-year point rainfall is about 3 inches in all 3 regions. With more data becoming available, especially from remote areas, more exact separation of thunderstorm types and a better definition of rainfall will soon be possible.
    • Use and Abuse of Southwestern Rivers: Historic Man - The Spaniard

      Polzer, Charles W.; Southwestern Mission Research Center, Tucson, Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      The early Spanish explorers did not lean toward rivers and boats. Bred in the culture of an arid land, they naturally explored with horses or by foot, leaving boats and rafts to the English and French. No historical records reveal any Spanish desires or attempts to control river flow or harness desert water resources on any appreciable scale. Yet they transformed the Sonoran desert into a productive garden land never before achieved by indigenous peoples. Pueblos were built on river banks where alluvial fans could be easily irrigated. Small arroyo check dams diverted water into wells and town tanks, while larger diversion dams were built to draw water into canals for crop irrigation. The dams were designedly weak and efficient only to the point of diverting sufficient water for the pueblo. There is no concept of storing water in reservoirs or lakes for periods of scarcity, but only of tapping enough water during periods of excess flow. All surplus water was allowed to flow downstream for the use of others in their struggle for survival. In this way the Spanish achieved a balance between human needs and the limited resources of the desert. The records of the Mexicans and the Anglos have been much more exploitive and destructive.
    • Use and Abuse of Southwestern Rivers: The Pueblo Dweller

      DiPeso, Charles C.; The Amerind Foundation, Inc., Dragoon, Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      In response to the 20th century crisis of environmental destruction by unrestricted technological exploitation, some archaeologists are studying alternative modes of resource development as practiced by earlier men. The pueblo Indians of the arid southwestern deserts were basically upland corn farmers, who, after A.D. 1000, found it necessary to exploit their environment because of varying combinations of climatic change and increased population pressures. In the northeastern part of the state of Chihuahua, urban engineers, ca 1050, harnessed the entire Casas Grandes dendritic pattern by installing a set of linked hydraulic appointments which included various upslope protective devices such as linear border, check dams and riverside and hillside terraces. Not only were they able to visualize an entire dendritic pattern as the target area, but also they were able to conceive of rainfall and topsoil as a single factor in their control designs. Although large amounts of human labor were needed to construct and maintain these systems, few raw materials were needed. When the mountain-born waters reached the lower valleys, they were clear and sluggish, did not flood the bottomlands, and because of the reduced speed, could easily be diverted into canals and reservoirs, supplying the cities with domestic water and the farmers with irrigation water. Many further studies are needed of these pre-Columbian systems.
    • Mulching Techniques for Arid Lands Vegetable Production

      Peebles, R. W.; Oebker, Norman F.; University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1971-04-23)
      Mulches have been used for evaporation suppression in facilitating vegetable production under arid lands conditions. A study was undertaken in order to evaluate the effectiveness of plastic aprons, supplied by the FAO, as compared to gravel mulches. The vinyl aprons were 6 mils thick and about 1 meter square. Squash plants (Cucurbita pepo) were planted with gravel or plastic aprons or in bare areas and under different watering schedules. The yields under plastic aprons were considerably greater than under gravel and required slightly less water. Bare soil yields lagged far behind. Soil temperatures under the plastic aprons were consistently higher over 24 hours than bare soil, which within limits, would facilitate faster crop growth. Additionally, the apron collects and diverts rainfall to the plant. The vinyl used lasts only 2 seasons, and gravel would probably be a more suitable mulch for developing countries where capital is scarce.
    • The Occurrence of Thermal Groundwater in the Basin and Range Province of Arizona

      Wright, Jerome J.; Geosciences, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1971-04-23)
      The distribution of groundwater having temperature considered to be higher than normal is examined on a regional basis. Much of the work was done by searching the literature and examining USGS records. The geographic distribution of the thermal waters is reviewed; relation to structure, geothermal gradients and water quality are discussed. Current and past utilization of thermal water from both springs and wells of the state has never been very extensive. Conclusions were: (1) the occurrence of thermal water in the state is closely allied to major structural elements, especially major fault zones; (2) geothermal gradients vary widely from place to place; (3) the extent of 'bedrock' influence on thermal water occurrence is difficult to ascertain; (4) most thermal water in southern Arizona is derived from meteoric water.
    • Progress in Developing Forest Management Guidelines for Increasing Snowpack Water Yields

      Thorud, David B.; Ffolliott, Peter F.; Department of Watershed Management, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1971-04-23)
      Snowmelt is a major source of runoff in Arizona for both reservoir systems and groundwater recharge. Because much of the Arizona snowmelt runoff occurs in ponderosa pine forests, it follows that appropriate forest management methods may enhance snowmelt water yield by manipulating tree spacing or overstory density. This paper attempts to establish guidelines for evaluating such forest management practices. Physiographic and climatic factors also affect runoff quantity, and it is conceivable that 2 sites of identical vegetation composition, but different in some combination of these factors might yield quite different amounts of runoff in response to some management practice. A pert network is presented illustrating the investigative framework for such a research effort. The major study activities of the framework are the identifying developing preliminary evaluations and preparing a comprehensive report. Three inventory evaluations to attempt identification of pertinent populations are currently being conducted and are described.
    • Uncertainties in Digital-Computer Modeling of Ground-Water Basins

      Gates, Joseph S.; | Kisiel, Chester C.; U.S. Geological Survey, Tucson, Arizona; Hydrology and Water Resources, University of Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      Much future computer modeling of the responses of groundwater to water development stresses may be poorly done if the errors and limitations of digital models are not fully appreciated by groundwater hydrologists. Two digital models were constructed of the Tucson basin, one with 1,890 nodes of 1/4 square mile area each and one with 509 nodes of 1 square mile each. The starting point for the digital model was the 2-dimensional, linear, parabolic, time-and space-invariant differential equation of incompressible flow through porous media. An explicit finite-difference equivalent was determined, and a set of 1,890 equations were put in implicit form and solved on a computer in less than 20 seconds at a cost of 2.00 dollars. The errors associated with the model are discussed. In deciding what new data collected in the Tucson basin would give the most improvement in the digital model, a statistical decision theory approach was utilized in which expected opportunity loss and expected worth of sample were calculated for 5 variables. The data was computed using about 110 seconds of computer time, costing about 13.00 dollars. This technique has the advantage of including basin dynamics in estimating worth of additional data by means of using the digital model to compute all values of predicted and 'true' water levels included in the loss function.
    • Conditional Streamflow Probabilities

      Roefs, T. G.; Clainos, D. M.; Hydrology & Water Resources, University of Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      Streamflows of monthly or shorter time periods, are, in most parts of the world, conditionally dependent. In studies of planning, commitment and operation decisions concerning reservoirs, it is probably most computationally efficient to use simulation routines for decisions of low dimensions, as planning and commitment, and optimization routines for the highly dimensional operation rule decisions. This presents the major problem of combining the 2 routines, since streamflow dependencies in simulation routines are continuous while the direct stochastic optimization routines are discrete. A stochastic streamflow synthesis routine is described consisting of 2 parts: streamflow probability distribution and dependency analysis and a streamflow generation using the relationships developed. A discrete dependency matrix between streamflow amounts was then sought. Setting as the limits of interest the class 400-500 thousand acre ft in January and 500-600 thousand acre ft in February, and using the transforms specified, the appropriate normal deviates were determined. The next serious problem was calculating the conditional dependency based on the bivariate normal distribution. In order to calculate the joint probability exactly, double integrations would be required and these use too much computer time. For the problem addressed, therefore, the use of 1-dimensional conditional probabilities based on the flow interval midpoint is an adequate and effective procedure.
    • The Use of a Realistic Rainfall Simulator to Determine Relative Infiltration Rates of Contributing Watersheds to the Lower Gila Below Painted Rock Dam

      Cluff, C. B.; Boyer, D. G.; Water Resources Research Center, University of Arizona; Hydrology and Water Resources, University of Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      The rotadisk rainulator is a recently developed rainfall simulator utilizing a full-cone-spray type nozzle. Its unique feature is the rotation of disks of various size openings that makes it possible to produce intensities from close to zero up to full nozzle capacity. Disks may be quickly changed, making it possible to study the effects of various intensities on infiltration rates, such as occur in natural storms. For all intensities above 1.0 in/hr, the instrument comes closer to duplicating kinetic energies and momenta of natural rainfall than any other type of rainfall simulator. Little rainfall-runoff data are available on most of the Lower Gila watersheds. Infiltration rates were therefore determined using the rotadisk rainulator on recompacted soil samples from the watershed. The results permitted a ranking of the watersheds on the basis of infiltration rates, which supports an independent flood frequency analysis indicating that the flood threat from subwatersheds along the Gila is much lower than had previously been projected. When the instrument is taken into the field, it should be possible to directly determine the infiltration rates of different soil and vegetation types, which will be of more use to hydrologists than data from recompacted samples
    • Comparison of Water Pricing Structures from a Collective Utility Viewpoint

      Metler, Bill; Duckstein, Lucien; Systems Engineering Department, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1971-04-23)
      As a result of continually lowering water tables in the arid regions of the west, many people are beginning to realize that water should be treated like any other rare resource, letting supply and demand factors regulate its distribution. Three types of price structures are used by water agencies: (1) the flat rate system (2) the step rate system and (3) the block rate system. Each of these structures may be progressive or regressive. At present, Tucson's only source of water lies underground and will presumably decrease as the population increases. To optimize the benefits to the community, it may be necessary to decrease not only average consumption but also summertime peak consumption for swimming pools, evaporative coolers and lawn sprinkling. Currently, Tucson uses a regressive block rate pricing structure. Using the theory of collective utility, a model is developed for use in comparing 2 price structures in an effort to define a monetary value for water conservation. It is concluded that the change in collective utility, du, which is a measure of the worth of change from economic state 1 to 2, is the best measure of price changes in arid areas. The model shows that Tucson water consumption would be lowered and money would be lost with either price structure, but with the permanent change, monetary flow of goods would be greater than under the seasonal structure.
    • Physiographic Limitations Upon the Use of Southwestern Rivers

      Breed, Carol S.; Museum of Northern Arizona, Flagstaff (Arizona-Nevada Academy of Science, 1971-04-23)
      Southwestern rivers are few in numbers and low in discharge. The physiographic and climatic reasons for this are discussed. To the east of the 100th meridian, rainfall is reliable and agriculture is stable; while to the west, there is a chronic deficit of water, droughts are frequent and lifestyles must be accordingly adjusted. Dam building results in greatly increased silting behind the dam in both the river and its tributaries and accelerated channel erosion below the dam. Total flow must also decrease due to withdrawals and increased evaporation from reservoirs. The correction of apparent errors in measuring the virgin flow of the Colorado River now indicates that this flow is about 15 maf/yr. Current legal allocations total 17.5 maf/yr of river water, including the central Arizona project (cap), which will withdraw 1.2 maf/yr. While the river is being dammed and overallocated beyond all reason, the water table is being mined at the alarming rate of 20 ft/yr. In central Arizona, it has dropped to about 250 ft below the surface, and even if all withdrawals ceased immediately, it would take many centuries of of desert rains before it would return to its former level of 50 ft. The cap water will cancel only about 1/2 of this overdraft annually. A glance at the phoenix area today shows that rain follows neither the farmers plow nor the subdividers bulldozer.
    • The Use of Chemical Hydrographs in Groundwater Quality Studies

      Schmidt, Kenneth D.; Harshbarger and Associates, Tucson, Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      High nitrates in drinking water are significant in relation to an infant disease, methemoglobinemia, and the U.S. public health service has set a limit of 45 ppm for human consumption. This paper illustrates how chemical hydrographs were used in a study of nitrates in the groundwater of the Fresno-Clovis metropolitan area (F.C.M.A.) of semiarid central California. The area comprises about 145 square miles, with a population of 310,000. Urban water use is entirely derived from wells, whereas the surrounding agriculture relies on surface and ground water. In 1965, the California department of water resources noted nitrate concentrations in the F.C.M.A. were exceeding the safe limit. A number of sources of error in chemical analyses of water quality are noted. A measure of the accuracies of analyses and a method of double-checking anomalous results is furnished by plotting chemical hydrographs of individual wells. Seasonal changes in nitrate were consistent for many parts of the area, and were related to hydrogeologic factors and parameters directly affecting nitrification. Nitrate hydrographs were monitored by chloride hydrographs. The highest nitrate concentrations were in the shallower parts of the aquifer, and well deepening and changes in water level, pumping patterns and recharge rates complicated interpretations. However, the hydrographs helped to pinpoint the source of nitrate in areas where several possible sources were present.
    • Hydrologic Effects of Soil Surface Micro-Flora

      Faust, William F.; Water Resources Research Center, The University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1971-04-23)
      Previous studies have indicated that blue-green algae may affect runoff, infiltration and erosion at soil surfaces. Using soil plots upon which blue-green algae were grown under an artificial wetting regime, studies were made using simulated rainfall. A 30% clay content Pima soil and a contrasting 8% clay content river-bottom anthony soil were used. Scytonema hoffmanii and Microcoleus vaginatus grew on the pima soil while Schizothrix calcicola developed on the Anthony soil. The results showed that blue-green algal growths significantly reduced the amount of suspended soil material in runoff water as compared with bare soils. Differences in runoff suspended sediments were also related to differences in soil type and simulated rainfall intensity. An analysis of variance of the effects of these 3 factors and their interactions showed that the smaller differences in suspended sediment production on the Anthony soil due to the microvegetation treatment was verified by a highly significant soils-microvegetation interaction, probably because the finer pima soils wash away more easily without stabilizing microvegetation. Also, less vegetation seems to grow on the Anthony soil. Differences in runoff and infiltration volumes and in settleable sediment amounts were not detected.