• 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.