• Applicability of the Universal Soil Loss Equation to Semiarid Rangeland Conditions in the Southwest

      Renard, K. G.; Simanton, J. R.; Osborn, H. B.; United States Department of Agriculture, Agricultural Research Service, Western Region, Southwest Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1974-04-20)
      An erosion prediction method that has recently received wide attention in the United States is the universal soil loss equation which is given as: a=rklscp. Where a = estimated soil loss (tons/acre/year), r = a rainfall factor, k = a soil erodibility factor, l = a slope length factor, s = a slope gradient factor, c = a cropping-management factor, and p = an erosion control practice factor. Data collected on the walnut gulch experimental watershed in southeastern Arizona were used to estimate these factors for semiarid rangeland conditions. The equation was then tested with data from watersheds of 108 and 372 acres. The predicted value of annual sediment yield was 1.29 tons/acre/year as compared with an average 1.64 tons/acre/year for 4 years of data for the 108-acre watershed, and a sediment yield of 0.39 tons/acre/year was predicted for the 372-acre watershed as compared with the measured value of 0.52 tons/acre/year. Although good agreement was noted between predicted and actual sediment yield, additional work is needed before the equation can be applied to other areas of the southwest.
    • Fresh Water for Arizona by Salt Replacement Desalination

      Muller, Anthony B.; Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1974-04-20)
      The process of salt replacement desalination proposed is believed to be able to produce vast quantities of fresh water be desalination. This method, which is a novel approach to minimizing the costs of saline water conversion, consists of the substitution of solutes in a solution to be desalted by a replacer chemical, and the low energy removal of that replacer chemical. The ultrafiltration of larger molecular sized replacer chemicals with high flux membranes increases the produce yield rate and reduces the corresponding energy requirement, with respect to reverse osmosis. In addition, the initial captial investment is less since no pressure constraining devices are required. The alteration of the osmotic pressure of the replacer solution within the process can also take advantage of energy savings through the utilization of an easily reversible reaction which synthesizes and breaks down a constituent that has a significant osmotic pressure difference between phases. Finally, the unusual process of fixed gel syneresis shows potential as a low energy salt replacement type process, but still requires extensive investigation.
    • United States-Mexico Water Agreements and Related Water Use in Mexicali Valley: A Summary

      DeCook, K. J.; Water Resources Research Center, The University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)
      A summary is given of interrelated, technical and institutional events concerning the Colorado River which took place between the United States and Mexico from 1849 to 1974 with emphasis on the 1961-1974 period. Until the treaty of 1944, Mexico had had no guarantee of a specific annual quantity of water, but in the years after 1945, when a guarantee of 1.5 million acre-feet per year was established, more than that amount was available for use. Salinity problems arose, and in 1965 an agreement for a 5-year plan for alleviating the technical and political difficulties surrounding the salinity question was made. In 1973 it was agreed that the United States would build, within approximately 5 years, a facility for desalting the saline drainage water entering Mexico. Fulfillment of the technical provisions for this agreement requires, in any event, the timely provision of federal funds to construct and operate the physical works. The several states should receive assurance that their rights and those of their respective water users will not be impaired within the legal operation of the agreement.
    • Laboratory Evaluation of Water-Repellent Soils for Water Harvesting

      Fink, Dwayne H.; U. S. Water Conservation Laboratory (Arizona-Nevada Academy of Science, 1974-04-20)
      Reported are laboratory evaluations to screen water-repellent materials and treatments before testing them in the field. Water repellency tests were conducted on paraffin wax, a wax emulsion and silicon, lard, and a liquid dust suppressant. Six water repellency tests showed that the high rates of paraffin wax and all rates of the dust suppressant produced highly water-repellent soil surfaces. The six water repellency tests were: (1) the aqueous-alcohol drop test for determination of the 90 degree surface tension for a porous solid, (2) the water drop penetration time test, (3) the relative height of a large sessile water drop resting on the smoothed, treated soil surface, (4) and (5) the presence and persistence of air bubbles trapped between the soil-water interface, and test (6) was made to note whether the large sessile water drop from test (3) would infiltrate the soil or evaporate. Tests (3), (4), and (5) proved the most useful of the six methods for measuring water repellency. Soil type had no significant influence on degree of water repellency as measured in the laboratory by these six tests.
    • Water Resource Alternatives for Power Generation in Arizona

      Smith, Stephen E.; DeCook, K. James; Fazzolare, Rocco A.; Nuclear Engineering, University of Arizona, Tucson; Water Resources Research Center, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)
      An examination of potential water sources for power plant cooling in Arizona is presented along with information pertinent to Arizona's future water needs relative to electrical usage growth. It has been projected that Arizona's peak electrical power demands in 1980 and 1990 will exceed that of 1970 by some 5000 megawatts and 16000 megawatts of electricity respectively. At present, the bulk of the electrical energy generated in the western states originates at hydroelectric installations. Utilization of nuclear reactors for power generation requires a larger amount of cooling water than is required for a comparable fossil-fueled plant. It is suggested that the utilization of reclaimed wastewater for cooling purposes is a viable and attractive alternative to groundwater pumpage from both economic and ecological standpoints. Savings arise from conservation of fuel normally required for well pumps, costs of well construction are not required, quantities of fresh water should be released for consumption by alternate users, and a previously unused resource would be effectively recycled.
    • Establishing a Process Framework for Land Use Planning (invited)

      Lundeen, Lloyd J.; Watershed Systems Development and Application Unit, U. S. Forest Service, Berkeley, California (Arizona-Nevada Academy of Science, 1974-04-20)
      The operational aspects of land use planning, to be effective, must be tied to a well defined planning process. The framework for this process includes a set of main components which are important in solving land use planning problems. These components are linked together in a design related to the basic concepts of decision analysis which has been oriented to natural resource problems. Detailed description can be added to the .process framework to tailor it to a specific problem, study area, or study level. Some of the major components in the framework are an objectives and goals spectrum, problem formulation, physical characterization of the land, social and economic demands analysis, identification of management alternatives and specific activities, simulation of resource response, allocation of resources, visual quality analysis, transportation system analysis, and a data management system. This process framework is d »sinned to he dynamic, user oriented, and compatible with the type of problems encountered in land use planning.
    • Water Resources Research on Forest and Rangelands in Arizona (invited)

      Hibbert, Alden R. (Arizona-Nevada Academy of Science, 1974-04-20)
      A progressive and coordinated effort is underway to provide a sound technical basis for managing water resources on forest and rangelands in the Southwest. An in-house Forest Service (USDA) research program including pilot testing and economic evaluations of multiple-use alternatives provides information necessary for this purpose. Demands for other goods and services also are increasing on these lands in the face of a burgeoning population. homeseekers, vacationers, and recreationists seek a variety of recreational. experiences that require open space and a relatively undisturbed environment. Frequently these uses conflict, and the combined pressure from too many activities can damage the environment. A new research effort has been organized in the central and southern Rocky Mountain Region to cope with these problems. Nine Western universities including Northern Arizona University, Arizona State University, and University of Arizona have joined forces with the Rocky Mountain Forest and Range Experiment Station to form the Eisenhower Consortium for Western Environmental Forestry Research. Simply stated, the consortium seeks to better our understanding of the relationships between man and his open-space environment in order that its quality might be maintained.
    • Hydrologic Aspects of Land-Use Planning at Tumamoc Hill, Tucson, Arizona

      Popkin, Barney Paul; Soils, Water and Engineering Department, The University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)
      Tumamoc Hill, an 869-acre (352 ha) desert area near Tucson, Arizona, is being considered as a controlled- access environmental site. Water affects the site's geology, soils, vegetation, wildlife, and archaeology. The Hill is drained by three small watersheds. The largest is rapidly urbanizing upstream. Hydrologic aspects include potential flooding and erosion hazards. These may be reduced simply, economically, and wisely in a land-use plan. Upstream development increases storm runoff volumes, and flood peaks, and frequencies routed through the site, and threatens existing downstream urban development. Return periods of channel-overflow floods become shorter with urbanization. The region may be managed to reduce hydrologic hazards by three procedures: widen channels, install low checkdams, and vegetate drainageways. These methods will slow down runoff velocities, and increase cross -sectional area of flow and roughness coefficient. More water would also be available for vegetation and wildlife. The land-use plan should include environmental education programs. These would present important effects of water on the natural ecology, and hydrologic aspects of watershed urbanization.
    • Assessing Soil-Water Status Via Albedo Measurement

      Idso, Sherwood B.; Reginato, Robert J.; ARS, USDA, U. S. Water Conservation Laboratory, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1974-04-20)
      Reliable information on soil-water status is required in order to make accurate water balance studies of watersheds, to determine the survival probabilities of various types of vegetation between rainfalls in low rainfall areas, and to determine the susceptibility of the uppermost soil to wind erosion. Simple solarimeters may help to accomplish this objective. Bare soil albedo was a linear function of the water content of a very thin surface layer of soil, and albedo correlated well with water contents of thicker soil layers. In addition, albedo measurements could be used to delineate the 3 classical stages of soil drying. Albedo may also be used to differentiate between the initial potential rate phase of evaporation following an application of water, and the succeeding falling rate phase. Results of applying this technique to a field of Avondale clay loam indicate that 20% to 25% of the water applied by either irrigation or rain will be lost by stage 1 potential evaporation, independent of seasonal variations in evaporative demand. Presently the techniques developed are applicable only to bare soil surfaces.
    • Using Linear Regression in Hydrological Design

      Peterson, G. D.; Davis, D. R.; Weber, J.; Department of Systems and Industrial Engineering, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)