• Academic Training for Groundwater Quality Specialists

      Schmidt, Kenneth D. (Arizona-Nevada Academy of Science, 1976-05-01)
    • Addition of a Carbon Pulse to Stimulate Denitrification in Soil Columns Flooded with Sewage Water

      Lance, J. C.; Gilbert, R. G.; U. S. Water Conservation Laboratory, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1976-05-01)
    • Application of a Double Triangle Unit Hydrograph to a Small Semiarid Watershed

      Diskin, M. H.; Lane, L. J.; Department of Hydrology and Water Resources, University of Arizona, Tucson; United States Department of Agriculture, Agricultural Research Service, Western Region, Southwest Watershed Research Center, Tucson, Arizona (Arizona-Nevada Academy of Science, 1976-05-01)
      Hydrographs of runoff from small watersheds in semiarid regions often have a sharp peak with a relatively short time of rise followed by a slower recession and a tail of low flow. This characteristic shape suggests the possible use of a double triangle unit hydrograph recently introduced to hydrology. The shape of this unit hydrograph is specified by four parameters, which may be estimated by an optimization procedure based on using the sum of absolute deviations or some other suitable criterion as an objective function. Rainfall and runoff data for a number of storm events on a small watershed in the Santa Rita Experimental Range in southeastern Arizona have been analyzed to test the above idea. Double triangle unit hydrographs were fitted to individual storm events. The differences in the shapes of individual unit hydrographs were found to be small so that they could be approximated by a single double triangle unit hydrograph.
    • Application of Carbon-14 Ground-Water Ages in Calibrating a Flow Model of the Tucson Basin Aquifer, Arizona

      Campana, Michael E.; Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1976-05-01)
      In 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.
    • Arizona Water: Uses and Sources Past, Present, and Future

      Davidson, Lucy (Arizona-Nevada Academy of Science, 1976-05-01)
    • Chlorofluorocarbons as Hydrologic Tracers, A New Technology

      Randall, J. H.; Schultz, T. R.; Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1976-05-01)
      The 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.
    • Construction, Calibration and Operation of a Monolith Weighing Lysimeter

      Sammis, Theodore W.; Young, Don W.; Constant, Charles L.; Department of Hydrology & Water Resources, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1976-05-01)
      Construction 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.
    • Determining Areal Precipitation in the Basin and Range Province of Southern Arizona - Sonoita Creek Basin

      Ben-Asher, J.; Randall, J.; Resnick, S.; Water Resources Research Center, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1976-05-01)
      A linear relationship between point precipitation and elevation in conjunction with a computer four-point interpolation technique was used to simulate areal rainfall over Sonoita Creek Basin, Arizona. The simulation's sensitivity and accuracy were checked against the official isohyetal map of Arizona (Univ. of Arizona, 1965) by changing the density of the interpolation nodes. The simulation was found to be in good agreement with the official map. The average areal-rainfall was calculated by integration. Cumulative rainfall amounts were assumed to be stochastically independent from one season to another. The seasonal precipitations of forty years (1932-1972) were subdivided into five groups. to check for binomial distribution. The binomial model fits the historical data adequately. The binomial model for cumulative seasonal areal-precipitation provides one way to compute the return period. This information will be necessary for decision-makers and hydrologists to predict the area's future water balance.
    • The Effect of an Intensive Summer Thunderstorm on a Semiarid Urbanized Watershed

      Boyer, D. G.; DeCook, K. J.; Water Resources Research Center, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1976-05-01)
      The University of Arizona Atterbury Experimental Watershed, located southeast of Tucson, Arizona has been instrumented for precipitation and runoff measurements since 1956. Early on the afternoon of July 16, 1975 an intense convective thunderstorm produced more than three inches of rainfall in less than 50 minutes as recorded in several rain gages located in the middle of one 8.1 square-mile desert subwatershed. Storm runoff from this rural subwatershed and an adjacent recently urbanized subwatershed filled the newly finished Lakeside Reservoir and topped the concrete flood spillway with a peak of greater than 3000 cfs, the greatest flow since monitoring began. An analysis of storm characteristics, along with previously available data from local urbanized watersheds, allows speculation on the effect of such an intensive storm in a highly urbanized area.
    • An Energy Budget Analysis of Evapotranspiration from Saltcedar

      Gay, L. W.; Sammis, T. W.; Ben-Asher, J.; School of Renewable Natural Resources, University of Arizona, Tucson; Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona; Water Resources Research Center, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1976-05-01)
      Energy 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.
    • Equilibrium Condition and Sediment Transport in an Ephemeral Mountain Stream

      Heede, Burchard H.; Rocky Mountain Forest and Range Experiment Station, Tempe, Arizona (Arizona-Nevada Academy of Science, 1976-05-01)
      Flow frequency curves supported the hypothesis that channel-forming flows are exceptional events in ephemeral mountain streams. This was substantiated by the lack of a relationship between sediment production and sediment yield. Numerous bed nickpoints indicated channel instability, despite gravel bars and log steps that are part of the slope adjustment processes. Due to differences in structural density between bars and steps, size distribution of the sediment deposits above them differs. Although only qualitative guidelines are presented, the watershed or wildlife manager should be in a position to utilize the formation of gravel bars and log steps for his management goals.
    • Erosion and Sedimentation in the Upper Gila Drainage, A Case Study

      Kingston, R. L.; Solomon, R. M.; Gila National Forest, Silver City, New Mexico (Arizona-Nevada Academy of Science, 1976-05-01)
      The upper Gila River in Arizona and New Mexico contains extremely diverse geology and soils. One geological formation that is somewhat unique to the Southwest and the upper Gila drainage is the Gila Conglomerate formation. In New Mexico, this conglomerate is extensive on the main Gila River drainage, accounting for over 35 percent of the main basin area. A case study was done on the 22,580 hectare (55,793 acres) Lake Roberts Watershed to assess the current sedimentation problem and its sources. This study revealed interesting patterns of lake surface area changes with volume changes of the original 28.3 hectare (70 acres) man-made reservoir over the last 12 years. Surface area reduction (19%) has progressed at a rate over twice that for volume reduction (9%). The source of the problem stems primarily from soils derived from highly sensitive Gila Conglomerate. The watershed is not uncharacteristic of the unique geology and soils typical of the upper Gila drainage and may furnish insight into sediment production and sources for much of the Gila headwater drainage in New Mexico.
    • Evaluating Water Quality Sampling Schedules Using Fecal Coliform Concentrations in Sabino Creek

      Motschall, Robert M.; Brickler, Stanley K.; Phillips, Robert A.; School of Renewable Natural Resources, University of Arizona, Tucson, Arizona; Civil Engineering, University of Arizona, Tucson, Arizona (Arizona-Nevada Academy of Science, 1976-05-01)
      Sabino Canyon Recreation Area, adjacent to Tucson, and a major water-based recreation complex within the Santa Catalina Mountains, Coronado National Forest, receives intensive recreational use. This natural water resource area with primary water contact activities was monitored for fecal coliform in accordance with U.S. Forest Service Regulation (FSM 2542.2). As part of a larger study, this report discusses the relationships between time, day, and location of sampling with fecal coliform bacterial concentrations in Sabino Creek. Analysis of Variance shows that fecal coliform concentrations were higher: 1) on Sunday than Wednesday, 2) at 4:00PM than 8:00AM or 12:00 Noon, and 3) in the lower section of the four miles of the study area. This research provides the U.S. Forest Service with baseline water quality data and a benchmark from which to continue an efficient water quality monitoring program.
    • Evaluation of Recharge Through Soils in a Mountain Region: A Case Study on the Empire and the Sonoita Basins

      Kafri, U.; Ben-Asher, J.; Water Resources Research Center, University of Arizona, Tucson 85721 (Arizona-Nevada Academy of Science, 1976-05-01)
      A 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.
    • Feasibility of Using Solar Energy for Irrigation Pumping

      Larson, Dennis; Fanmeier, D. D.; Matlock, W. G.; Day, John; Sands, C. D., II; Soils, Water and Engineering Department, University of Arizona, Tucson, Arizona; Agricultural Economics Department, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1976-05-01)
      Solar 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.
    • Future Effects of the CAP on Lake Havasu's Thermal Regime

      Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1976-05-01)
      A temperature-stratification model developed by the U. S. Army Corps of Engineers, Hydrologic Engineering Center, was used to predict the changes in the temperature profile of Lake Havasu on the Colorado River near Parker, Arizona, that may occur with the withdrawal of Central Arizona Project (CAP) water in the 1980's. This quantified change in temperature-dependent density stratification was calculated using maximum withdrawal conditions to accentuate and expose any major changes which could be potential problems. Inputs for this program include monthly evaporation and precipitation, monthly average air temperature, solar radiation at the top of the atmosphere, water inflow amount and temperature, water outflow amount and location, water temperature profiles, and physical reservoir data. In the calibration of the model, the five coefficients were found to differ slightly from regional coefficients established by the Hydrologic Engineering Center, Davis, California, and coefficients established in a previous study. End of month temperature profiles were then generated for average meteorological conditions, both with and without maximum CAP flow. The computed results indicate that the stratification changes will be of low magnitude.
    • Geomorphic Thresholds and Their Influence on Surface Runoff from Small Semiarid Watersheds

      Wallace, D. E.; Lane, L. J.; Southwest Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1976-05-01)
      The geomorphic threshold concept of landform evolution and its effect on hydrologic performance of drainage systems was investigated on small semiarid watersheds in Southeastern Arizona. Thresholds develop within a geomorphic system with time and can, when exceeded, cause drastic changes in the geomorphic features and in the hydrologic performance of the watershed. The slow continuous evolution of drainage characteristics can be suddenly altered with major readjustment of the landscape taking place. A new state of dynamic equilibrium will then prevail until the drainage system is again subjected to conditions which cause some geomorphic threshold to be exceeded. Areas of potential geomorphic readjustment can be identified from parameters such as channel slope, average land surface slope, drainage density, and mean length of first order streams and these data can be used as components in a calibrated kinematic-cascade model to determine the effects of various degrees of drainage system alteration. The influence on runoff from exceeding various geomorphic thresholds is tested and the resulting hydrologic modifications are simulated and discussed.
    • Laboratory Weathering of Water-Repellent Wax-Treated Soil

      Fink, Dwayne H.; U. S. Water Conservation Laboratory, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1976-05-01)
    • Lysimeter Snowmelt in Arizona Ponderosa Pine Forests

      Jones, Mikeal E.; Ffolliott, Peter F.; Thorud, David B.; School of Renewable Natural Resources, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1976-05-01)