• Groundwater Geology of Fort Valley, Coconino County, Arizona

      DeWitt, Ronald H. (Arizona-Nevada Academy of Science, 1973-05-05)
      All groundwater in fort valley is presently found in perched aquifers. The regional water table in the area is estimated to lie at a depth of approximately 1750 feet. Groundwater reservoirs are perched on impermeable clay zones located at the base of alluvial units. Groundwater is also found in highly fractured volcanic zones overlaying impermeable clay zones. Perched aquifers also occur in interflow zones above either impermeable clays or unfractured volcanics. Groundwater in fort valley is the result of infiltration or runoff and from precipitation. This recharge water infiltrates the alluvium or fractured volcanic rocks until an impermeable zone is reached where it becomes perched groundwater. Greatest well yields come from these recharge aquifers; their reliability is largely dependent on precipitation and runoff. Most wells in the fort valley area supply adequate amounts of water for domestic use.
    • Groundwater Recharge from a Portion of the Santa Catalina Mountains

      Belan, R. A.; Matlock, W. G.; Soils, Water and Engineering Department, The University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1973-05-05)
      The geohydrology of a portion of the Santa Catalina Mountains including the definition of aquifer systems in the foothills was studied in order to calculate groundwater recharge to the Tucson basin. This underlying groundwater aquifer is the only source of Tucson, Arizona's water supply. A well network, well logs, geologic profiles, and a water level contour map were used as source information. Recharge was found to occur in some sections of washes and close to the mountains where washes cross or coincide with faults. Significant recharge to sand and gravel aquifers occurs directly through faults and joints. Little of the surface runoff is thought to recharge local aquifers because of low permeability layers beneath the alluvium and the short duration of the flows. Recharge calculation using the Darcy equation was subject to considerable error; but flow net analysis showed the total recharge to be 336 acre-feet per year representing about 50 acre feet per mile of mountain front per year.
    • Stationarity in Thunderstorm Rainfall in the Southwest

      Mills, William C.; Osborn, Herbert S.; USDA, ARS, Soil, Water and Air Sciences; USDA, ARS, Southwest Watershed Research Center, Tucson, Arizona (Arizona-Nevada Academy of Science, 1973-05-05)
    • Effects of a Wetting Agent on the Infiltration Characteristics of a Ponderosa Pine Soil

      Kaplan, Marc G.; Zwolinski, Malcolm J.; Department of Watershed Management, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1973-05-05)
      An infiltration- wetting agent study, using the wetting agent "WATER-IN", was conducted in the ponderosa pine forest type of east central Arizona. An application rate of 10 gallons of wetting agent per acre was used on bare mineral soil and on ponderosa pine litter. The infiltration rate was measured by a modified North Fork infiltrometer. It was found that "WATER-IN" significantly increased water runoff when applied to litter, but, when applied to bare mineral soil, "WATER-IN" caused a significant increase in water infiltration. The wetting agent did not significantly affect antecedent moisture, soil particle distribution, litter water holding capacity, or litter bulk density. It is presently hypothesized that the increase in water infiltration on treated bare mineral soil is due to a decrease in the average bulk density of the surface inch of soil. The increase in runoff when litter is treated is probably due to an interaction, either physical, chemical, or both, between the humus layer and "WATER-IN ", creating a hydrophobic condition where one did not exist before.
    • A Preliminary Assessment of Snowfall Interception in Arizona Ponderosa Pine Forest

      Tennyson, Larry C.; Ffolliott, Peter F.; Thorud, David S.; Department of Watershed Management, University of Arizona, Tucson 85721 (Arizona-Nevada Academy of Science, 1973-05-05)
      A preliminary assessment and ranking of the relative significance of five processes that may contribute to snow removal from ponderosa pine forest canopies was made, including wind erosion of canopy snow, snowslide from the canopy, stemflow, vapor transport from melt water, and vapor transport of canopy snow. The first three represent delayed delivery rather than net water loss. A snow load index was obtained through use of time lapse photography of the study site canopy, while incoming solar radiation and atmospheric processes were monitored. The snow load index was expressed as a ratio of forest canopy area covered with snow to the total canopy area. Results obtained over a 4-day period following a six-hour snowstorm showed that snow removal by snowslide and wind erosion was of significant importance, while vapor transport of melt water and canopy snow, stemflow, and dripping of melt water was of comparatively minor importance.
    • Probability Distributions of Snow Course Data for Central Arizona

      Carv, Lawrence E.; Beschta, Robert L.; Department of Watershed Management, University of Arizona, Tucson 85721 (Arizona-Nevada Academy of Science, 1973-05-05)
      A preliminary study of probability distributions for use on snowpack accumulation in the central Arizona highlands was made from 22 snow courses selected as having 10 or more years of available records. Due to the frequent occurrence of zero water equivalent value, application of a single continuous probability distribution is precluded. By means of two distributions, however, the snowpack water equivalent can be assessed by a binomial distribution describing the probability of snow, and a lognormal distribution describing the probability of water equivalent. The area chosen for detailed analysis is where the headwaters of many of Arizona's major river systems occur.
    • Use of Stock Ponds for Hydrologic Research on Southwest Rangelands

      Simanton, J. R.; Osborn, H. B.; USDA, ARS Soil, Water, and Air Sciences; Southwest Rangeland Watershed Research Center, Tucson, Arizona (Arizona-Nevada Academy of Science, 1973-05-05)
      Five livestock watering ponds on the walnut gulch experimental watershed were instrumented to evaluate the use of these ponds as a method for comparing rainfall amounts with runoff sediment volumes. Pond drainage area, vegetative cover, soil type, percent slope, and years of record were tested. Instrumentation consisted of water level recorders, and a topographic survey of each stock pond to ascertain its storage capacity. The results to date have been insufficient to reach definite conclusions due to instrumentation and surveying problems, and because of the natural variability of thunderstorm rainfall. Since most of these problems have now been corrected, future data should yield valuable hydrologic data for semiarid rangelands by means of these instrumented stock ponds.
    • Invited Topical Speaker: Sol Resnick, Impact on the Environment by Water Resources Development (Abstract)

      Resnick, Sol; Water Resources Research Center (Arizona-Nevada Academy of Science, 1973-05-05)