• Effect of Urbanization on Runoff from Small Watersheds

      Kao, Samuel E.; Fogel, Martin M.; Resnick, Sol D.; Water Resources Research Center, The University of Arizona, Tucson, Arizona 85721 (Arizona-Nevada Academy of Science, 1973-05-05)
      Hydrologic data collected from three small urban watersheds and one rural watershed were analyzed for the purpose of investigating the effect of urbanization on runoff. A procedure developed by the Soil Conservation Service was used to explain the relationship between the amount of rainfall and runoff. It was noted that the runoff curve number, a parameter of the method, increased as the percentage of impervious area increased. Also, there was evidence that a linear relationship existed between the runoff volume and its corresponding peak rate.
    • 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.
    • 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.
    • A Jeep-Mounted Rainfall Simulating Infiltrometer

      Henkle, William R.; Northern Arizona University (Arizona-Nevada Academy of Science, 1973-05-05)
      An infiltrometer was designed to more closely simulate natural storm characteristics and still maintain sufficient portability to be used in various test sites in the field. In addition to portability, a relatively large test plot can be used over a relatively long duration. The instrument is designed to produce rainfall intensities of 2 to 6 inches per hour which are comparable to natural storm intensities found in northern Arizona. Capillary tubes produce water drops of equivalent kinetic energy at impact to natural raindrops. Errors due to lateral flow are minimized through peripheral wetting. Mounting the infiltrometer on a four-wheel drive vehicle allows nearly the portability of a hand carried unit with a greater water carrying capacity and allows the equipment to be large enough to test a representative plot.
    • 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.