• Recent Changes in a Flood Series

      Reich, Brian M.; Engineering Division, City of Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
    • Reclamation of Wastewater for Open Access Irrigation

      Hager, Donald G.; Rubel and Hager, Inc., Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
    • Santa Cruz River Changes South of Tucson

      Lowe, Phillip O.; Engineering Division, City of Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
    • Uncertainties in Identifying Precipitation Trends in Arizona and New Mexico

      Osborn, Herbert B.; Frykman, Louis J.; USDA, ARS Southwest Rangeland Watershed Research Center, Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
    • Stream Order in Ephemeral Watercourses: A Preliminary Analysis from the Sonoran Desert

      Johnson, R. Roy; Warren, Peter L.; Anderson, L. Susan; Lowe, Charles H.; Cooperative National Park Resources Studies Unit, University of Arizona, Tucson, Arizona 85721; Arizona Remote Sensing Center, Office of Arid Lands Studies, University of Arizona; Department of Ecology and Evolutionary Biology, University of Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
    • The Growth and Survival of "Naturally-Occurring" Bacteria in Well Water

      Stetzenbach, L. D.; Yates, M. V.; Gerba, Charles P.; Sinclair, N. A.; Department of Microbiology and Immunology, University of Arizona, Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
      Ground water is an increasingly significant source of potable water that has traditionally been considered safe for human consumption without treatment. Although routinely monitored for the presence of coliforms, information concerning the non-coliform bacteria present in well water has been largely ignored. The purpose of this study was to demonstrate the ability of non-coliform, "naturally-occurring" bacteria to increase in number and persist in unamended well water. Water was collected from 19 continuously pumping wells throughout the Tucson basin and stored at in situ well water temperatures. Bacteria were enumerated using epifluorescent microscopy at predetermined intervals over a 30-day period. Greater than 3 log increases in bacterial numbers were noted after 24 hours of incubation. Maximum numbers were achieved after 3 days followed by a gradual decline ranging from 0.39-1.84 logs. Non-coliform, opportunistic pathogens have been isolated from Tucson well water. Their increase in number and survival in well water may impact the quality of untreated drinking water.
    • Impact of Urban Conservation on Groundwater Pumping and Projected Effluent Flow in the Tucson Area

      Foster, Kennith E.; Brittain, Richard G.; DeCook, K. James; Office of Arid Lands Studies; College of Architecture; Cooperative Extension Services (Arizona-Nevada Academy of Science, 1984-04-07)
    • Runoff Farming Agronomic System: Applications and Design Concepts

      Fink, Dwayne H.; Ehrler, William L.; USDA-ARS, U. S. Water Conservation Laboratory, Phoenix, AZ 85040; Amerind Agrotech Laboratory, Sacaton, AZ 85247 (Arizona-Nevada Academy of Science, 1984-04-07)
    • A Novel Method of Evaporation Suppression in a Water Harvesting System

      Karpiscak, Martin M.; Foster, Kennith E.; Rawles, R. Leslie; Office of Arid Lands Studies, College of Agriculture, University of Arizona, Tucson, Arizona 85719 (Arizona-Nevada Academy of Science, 1984-04-07)
      A demonstration agrisystem located in an area receiving less than 250 mm rainfall annually has been constructed through a cooperative program between the City of Tucson and the University of Arizona. Mondell pine, aleppo pine, jojoba, grapes, eucalyptus, olives, and other crops were cultivated in a 4 ha NaC1 treated catchment system designed to concentrate rainfall on plants and channel excess water into a system of storage reservoirs. Evaporation was reduced from an 80 foot diameter above ground reservoir by means of 225,000 plastic film cans, at a cost of approximately 50 cents /ft². Data acquired from evaporation pans indicates a 50 to 70 percent reduction in evaporation of the stored water. Additionally, this research has provided data that 1) demonstrates the economic potential for agriculture of currently retired farmland, 2) investigates the feasibility of applying water harvesting method for agricultgural purposes in a semiarid region, and 3) evaluates water harvesting as an alternative to meet the ever increasing demand for water.
    • Effect of Stream Discharge on Phosphorus Loading and Assimilation in the East Verde River

      Athey, Patrick V.; Sommerfeld, Milton R.; Department of Botany and Microbiology, Arizona State University, Tempe, AZ 85287 (Arizona-Nevada Academy of Science, 1984-04-07)
    • Evaluation of Nitrate in Groundwater South of Tucson, Arizona

      Postillion, Frank G.; Pima Association of Governments, Tucson, AZ (Arizona-Nevada Academy of Science, 1984-04-07)
      Levels of nitrates in excess of the US EPA standard of 45 mg/l were found in well water south of Tucson, Arizona. Most groundwater in this area with high nitrate content is beneath lands presently or formerly irrigated. The highest nitrate contents are present in the upper several hundred feet of the aquifer suggesting a source at the land surface. Nitrate contents in water from most wells in the study area were less than 7 mg/l in the late 1940's, but by the mid-1960's the nitrate level exceeded 25 mg/l in most wells. In the summer of 1982, more than 12 wells exhibited water with a nitrate content exceeding 45 mg/l. Analytical techniques included assessment of pollution sources at the land surface, chemical indicators such as chlorides, nitrogen and oxygen isotopes, and evaluation of the hydrogeologic conditions in the study area. Sources of nitrate contamination included sewage effluent disposal into the Santa Cruz River, historical irrigation practices, septic tank area, and an abandoned hog farm.
    • Questions Raised by the Tucson Flood of 1983

      Baker, Victor R.; Department of Geosciences, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1984-04-07)
      Post-disaster studies of the October 1983 flood lead to serious questions concerning the applicability to southern Arizona of nationally standardized procedures for flood hazard evaluation. When the U.S. Water Resources Council method of determining flood flow frequency is applied to the Santa Cruz River annual peak flow record at Tucson for the period 1915-1982, the 1983 flood discharge is predicted to have an exceedence probability of less than 0.001. Hydro-climatological considerations suggest that such large floods occur much more frequently. The standard procedure for flood hazard zonation utilizes step-backwater calculations for the extant channel and valley floor geometry to route the discharges obtained from the standard flood flow frequency analysis. This procedure, as used in the Federal Emergency Management Agency flood insurance study, greatly overestimated the areas of overbank flooding along the Santa Cruz River as experienced in the 1983 flood. A detailed post-flood study was performed to assess channel change for reaches of Pantano Wash, Tanque Verde Creek, the Rillito, and the Santa Cruz River in the Tucson Basin. Bank erosion occurred as cutbank recession of actively migrating meander bends except where local areas of bank were preserved by revetments. Where revetments remained intact during the flooding they served to concentrate and enhance bank erosion in the unprotected reaches immediately downstream. From an overall river management perspective, piecemeal bank protection generates greater channel instability than does no protection at all.
    • A Modified Cover Parameter Value for the Universal Soil Loss Equation

      Jemison, Roy L.; School of Renewable Natural Resources, University of Arizona, Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
      The Universal Soil Loss Equation (USLE) was formulated for estimating soil loss from agricultural lands in the eastern United States. It has also proven to be useful in assisting land managers make better decisions for other land uses. Studies have shown that when the equation is used in areas other than where it was developed, predictions may be inadequate due to variations in estimates of the environmental parameters used in the equation. Ten years of rainfall, runoff, and sediment yield data collected by the USDA /Agricultural Research Service were used to evaluate several cover parameter values (C) presently in use in the Southwest. Preliminary analysis of data showed no statistical differences between calculated and measured cover parameter values.
    • Stormflow Analysis of Chaparral Conversion of Small, Central Arizona Watersheds

      Alberhasky, Jo Ellen; Hibbert, Alden R.; Arizona State University, Tempe, AZ 85287; Rocky Mountain Forest and Range Experiment Station, Tempe, AZ (Arizona-Nevada Academy of Science, 1984-04-07)
      A stormflow analysis was done on streamflow records from low density chaparral watersheds, located in central Arizona, that had been converted from brush to grass to determine the effect of vegetation manipulation on stormflow parameters. The Hewlett-Hibbert hydrograph separation technique was used to separate streamflow into quickflow (flashier response) and delayed flow (more controlled response). Differences in quickflow and delayed flows between treated and untreated watersheds were tested statistically by using covariance techniques based on paired watersheds. The results of the stormflow analysis showed that the conversion of brush to grass increased both quickflow and delayed flow about 30 percent. When this increase was based on an average stormflow it resulted in about a 0.04 inch rise in quickflow and a 0.01 inch rise in delayed flow. Brush to grass conversion affected the complete range of streamflows measured although the larger flows were more variable. The 30 percent increase in the quick and delayed flow components suggested that: 1) conversion produced a uniform rise in the stormflow hydrograph as opposed to affecting any single parameter, and 2) as such, produced no major changes in the runoff patterns.
    • The Biodynamic Treatment of Wastewater

      Buras, Netty; Department of Civil Engineering, University of Arizona, Tucson, AZ 85721 (Arizona-Nevada Academy of Science, 1984-04-07)
      A wastewater treatment is proposed. It is based on: 1. The assumption that the changes taking place during the transformation of wastewater into effluent are unidirectional processes, entailing a number of well- defined sequential stages, and 2. The knowledge that the aerobic bacterial populations present in wastewater are able to decompose efficiently the organic matter in the wastewater, given optimal conditions for their development. Preliminary experiments in which these assumptions have been tested showed the production of a high quality effluent, as measured by the conventional chemical, physical and public health standards. No pathogenic bacteria or human enteric viruses have been recovered from the effluent so produced. A comparison between the processes of the "conventional biological" and a "biodynamic" treatment will be presented.
    • Costs and Returns to Irrigation Under the Central Arizona Project: Alternative Futures for Agriculture

      Bush, David B.; Martin, William E.; Department of Agricultural Economics, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1984-04-07)
    • Microbial Contamination of Groundwater in the Pinetop-Lakeside Area of Northern Arizona

      Mohrbacher, Carl; De Leon, Ricardo; Toranzos, Gary A.; Mullinax, Rebecca L.; Gerba, Charles P.; University of Arizona, Tucson, Arizona (Arizona-Nevada Academy of Science, 1984-04-07)
      The Pinetop-Lakeside area located in southeastern Navajo County, Arizona, has experienced several outbreaks of probable waterborne gastroenteritis. The many on -lot sewage disposal systems, thin soils and fractured crystalline rock aquifers make this area especially vulnerable to biological degradation of the groundwater supply. This study was designed to assess the extent of bacteriological and virological contamination of groundwater and relationships between indicatior bacteria, coliphages and human pathogenic viruses. Twenty different wells were selected and monitored for conforms, fecal conforms, fecal streptococci, coliphages, enteric viruses, and various physical and chemical properties of the water. Extensive microbial contamination of the groundwater was observed, which increased dramatically after a period of heavy rainfall. Almost 90% of all well samples contained coiform levels in excess of drinking water standards.
    • Effect of Storage Temperature on Survival of Coliforms in Ground Water

      Kutz, S. M.; Sinclair, N. A.; Department of Microbiology and Immunology, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1984-04-07)
    • Implementation of Isotope Subroutine to Computer Program PHREEQE and their Application to C-14 Ground Water Dating

      Cheng, Song-Lin; Long, Austin; Laboratory of Isotope Geochemistry, Department of Geosciences, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1984-04-07)
      The age of ground water is defined as the length of time the water has been isolated from the atmosphere. Among the methods for ground water dating, C14 is the most commonly used and the most intensively studied tool. The concentration of C14 in dissolved inorganic carbon can change as a result of chemical processes in nature, hence, an adjustment factor Q is included in the age equation. A = QAo(e^(- λt)) Various models have been proposed to account for this adjustment factor. Among those models, the mass transferbalance approach is the most rigorous method. Wigley, Plummer, and Pearson (1978) formulated a mass balance equation to calculate the evolution of C13 and C14 in natural water systems closed to soil CO2 gas. Deines, Langmuir, and Harmon (1974) used a set of dual chemical-isotopic equilibrium equations to calculate changes of C13 in systems open to soil CO2 gas. This study implements these two models as a subroutine and adds carbon isotope mixing equations to PHREEQE (Parkhurst, Thorstenson, and Plummer, 1980), which is a computer program for general hydrogeochemical calculations. With this program package, it is now possible to simulate the evolution of chemical and carbon isotopic compositions, including C14, of ground water from open to closed systems. These simulations allow much improved inferences of Q factors for radiocarbon groundwater dating.