• 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.
    • 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.
    • 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.
    • 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.
    • Tree-Ring Dating of Colorado River Driftwood in the Grand Canyon

      Ferguson, C. W.; Laboratory of Tree-Ring Research, The University of Arizona, Tucson, Arizona, 85721 (Arizona-Nevada Academy of Science, 1971-04-23)
      The development of tree-ring chronology for bristlecone pine (Pinus aristata), stretching over 8,200 years, has been used to calibrate the radiocarbon time scale. An extensive deposit of driftwood in Stanton's cave in the grand canyon was estimated to have been deposited on the cave floor about 12,000 years ago on the basis of the 4,095-year radiocarbon age of a split-twig figurine on the surface of the cave floor. However, the initial driftwood specimen gave the surprising C-14 age of 35,000 years. A tree-ring dating study was therefore undertaken on driftwood in the grand canyon in order to: (1) evaluate the driftwood deposit in Stanton's cave; (2) provide a basis for interpreting c-14 dates from canyon archaeological sites; and (3) document a technique for deriving some concept of pre-dam hydrology, especially maximum high water levels. The percentage of dated specimens found indicated that the approach was feasible. A likely interpretation of the seemingly early c-14 dates at archaeological sites is that prehistoric man used old driftwood, as does modern man in the canyon. Tree-ring dates from wood above the pre-dam high water mark indicate that maximum 100-year flood evidence can be obtained.
    • Nitrogen Balance for a 23-Square Mile Minnesota Watershed

      Johnson, Jack D.; Office of Arid Land Studies, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1971-04-23)
      The nitrogen balance of a watershed near the city of New Prague, Minnesota was evaluated as part of an overall study on lake and stream eutrophication. Although the n-balance of a humid Midwest watershed cannot be expected to be identical to that of an arid watershed, the processes are the same and differences should be mainly quantitive. Sources of input and causes of depletion are reviewed for 4 points in the nitrogen cycle: the atmospheric zone, the soil-atmosphere interface, the plant-root and soil-water zone and the surface water zone. In the New Prague watershed, commercial fertilizer and bulk precipitation were the major sources of input, contributing, respectively, 53% and 34.4% of the total input of 2.34 million lb/yr. Crop yield and soil or groundwater storage contributed 52.1% and 20.4% of non-enrichment depletions. The closeness of the values of crop yield and commercial fertilizer application was an unfortunate coincidence and is certainly not an indication that the entire fertilizer supply was taken up cry crops. In an arid environment, free from fertilized agriculture, bulk precipitation probably provides the major source of nitrogen compounds.
    • Field Measurements of Soil-Water Content and Soil-Water Pressure

      Reginato, R. J.; 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)
      Knowledge of the dynamic water content-pressure potential relationship within the soil profile is useful in determining the importance of hysteresis under natural conditions. Continuous monitoring of water content in the field is now possible using recently developed gamma-ray transmission equipment which allows water content measurements in 1 cm-thick soil layers with an error of 0.0009 gm/gm. The nuclear equipment and the tensiometer assembly for pressure measurements are described. Soil water content and pressure in the top 10 cm of a field soil profile were measured continuously for a 2-week period following an irrigation. The highest water content was measured each day just before sunrise. This declined rapidly from early morning to early afternoon, and was followed by a gain during the mid-afternoon and evening. The amplitude of this diurnal change diminished with time after irrigation. The pressure potential at a depth of 1.5 cm decreased most rapidly as the water content declined, but not exactly in phase. This may have been due to temperature effects on the pressure metering system. A moisture characteristic curve was constructed from the data.
    • 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.
    • 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.
    • 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.
    • Effects of Fire on Water Infiltration Rates in a Ponderosa Pine Stand

      Zwolinski, Malcolm J.; University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1971-04-23)
      The importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed.
    • 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.
    • 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.
    • 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.
    • Use and Abuse of Southwestern Rivers: Historic Man - The Anglo

      Fireman, Bert; Arizona State University, Tempe, Arizona (Arizona-Nevada Academy of Science, 1971-04-23)
      The exploitation of southwestern rivers is discussed in the context of American intrusion, acquisition and development of Arizona. The first Americans in the region were beaver trappers who quickly decimated the Sonoran beaver but otherwise wrought little environmental impact. Immediately following the acquisition of the region by the U.S. after the Mexican war, gold miners descended upon it from California. They quickly scarred hills and streams, diverting water for placers, building piles of ugly rubble and logging off entire forests. The large numbers of people and towns that followed created a need for more home grown food products and large storage dams were soon built. When these washed out the stored floodwaters did more sharp, tragic damage downstream than even the seasonal floods of the past. The common municipal practice of dumping raw sewage into waterways soon brought water pollution. Following the national reclamation act of 1902, large dams were soon built on major waterways and the multiple use projects came into existence. Today, even the Indians, in their quest for economic betterment are destroying natural waters. They have learned a major lesson from the whites---the rivers they used only for basic needs a century ago, may be more profitable if overused without regard for tomorrow.
    • 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.
    • 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.
    • 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.