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121	A Technique to Evaluate Snowpack Profiles in and Adjacent to Forest Openings Ffolliott, Peter F., Thorud, David B. 20 April 1974 (has links) From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Profiles of snowpack build-up in openings in forest overstories have been widely observed; however, a quantitative characterization of such a snowpack profile would aid in developing empirical guidelines for improving water yields from snowpacks. A technique is outlined that illustrates (a) evaluating snowpack profiles in and adjacent to individual forest openings in terms of increase or decrease in water equivalent, and (b) defining trade-offs between the estimated increase or decrease in snowpack water equivalent and the forest resource removed. Snowpack water equivalent during peak seasonal accumulation was measured in and adjacent to a clearcut strip in a ponderosa pine stand in north-central Arizona. A 4-degree polynomial, which defines the snowpack profile in terms of deposition, redistribution, and ablation characteristics, was empirically selected to describe snowpack water equivalent data points. An increase of 60 percent in snowpack water equivalent was realized by removing 46 percent of the ponderosa pine in the zone of influence, using a strip equal to one and one-half the height of the adjacent overstory. Hydrology -- Arizona. Water resources development -- Arizona. Hydrology -- Southwestern states. Snowpacks Arizona Vegetation effects Ponderosa pine trees Snow management Snow Canopy Forests Evaluation Estimating Water equivalent Water yield Strip cutting Forest openings Snow accumulation
122	Effects of Fire on Water Infiltration Rates in a Ponderosa Pine Stand Zwolinski, Malcolm J. 23 April 1971 (has links) From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed. Water resources development -- Arizona. Hydrology -- Arizona. Hydrology -- Southwestern states. Burning Infiltration Soil chemical properties Forest soils Watersheds Ponderosa pine trees Arizona Infiltrometers Soil temperature Overwintering sites Frost action Soil texture Porosity Forest fires Forest management Water repellent soils
123	An Analysis of Yearly Differences in Snowpack Inventory-Prediction Relationships Ffolliott, Peter F., Thorud, David B., Enz, Richard W. 06 May 1972 (has links) From the Proceedings of the 1972 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 5-6, 1972, Prescott, Arizona / Inventory-prediction relationships between snowpack conditions and forest attributes may be useful in estimating water yields derived from snow, but such relationships are developed usually from source data collected over a short time period. Analyses of long-term data suggest inventory-prediction relationships developed from limited data may have more general application, however. Available records from 18 snow courses in the ponderosa pine type in Arizona provided source data in this study, which was designed to empirically analyze inventory-prediction relationships developed from long-term snow survey records. The primary hypothesis tested and evaluated by statistically analyzing the family of regression equations representing a snow course, was that, given a precipitation input, the distribution of snowpack water equivalent at peak seasonal accumulation is determined by the spatial arrangement of the forest cover, e.g. basal area. Generally 12 of the 18 snow courses evaluated appeared to support the hypothesis, three courses did not, and three courses were considered inconclusive. Hydrology -- Arizona. Water resources development -- Arizona. Hydrology -- Southwestern states. Runoff forecasting Snowpacks Spatial distribution Forest management Vegetation effects Arizona Forecasting Census Forests Watershed management Snow surveys Water equivalent Water yield Snow management Canopy Inventory-prediction Ponderosa pine
124	Progress in Developing Forest Management Guidelines for Increasing Snowpack Water Yields Thorud, David B., Ffolliott, Peter F. 23 April 1971 (has links) From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Snowmelt is a major source of runoff in Arizona for both reservoir systems and groundwater recharge. Because much of the Arizona snowmelt runoff occurs in ponderosa pine forests, it follows that appropriate forest management methods may enhance snowmelt water yield by manipulating tree spacing or overstory density. This paper attempts to establish guidelines for evaluating such forest management practices. Physiographic and climatic factors also affect runoff quantity, and it is conceivable that 2 sites of identical vegetation composition, but different in some combination of these factors might yield quite different amounts of runoff in response to some management practice. A pert network is presented illustrating the investigative framework for such a research effort. The major study activities of the framework are the identifying developing preliminary evaluations and preparing a comprehensive report. Three inventory evaluations to attempt identification of pertinent populations are currently being conducted and are described. Water resources development -- Arizona. Hydrology -- Arizona. Hydrology -- Southwestern states. Forest management Snowmelt Runoff Water yield improvement Project planning Ponderosa pine trees Vegetation effects Soil types Topography Climatic data Runoff forecasting Arizona Mountains Pert networks Runoff efficiency
125	Probability Distributions of Snow Course Data for Central Arizona Carv, Lawrence E., Beschta, Robert L. 05 May 1973 (has links) From the Proceedings of the 1973 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 4-5, 1973, Tucson, Arizona / 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. Hydrology -- Arizona. Water resources development -- Arizona. Hydrology -- Southwestern states. Snowfall Water yield Probability Distribution patterns Water equivalent Arizona Snowpacks Snow Ponderosa pine trees Coniferous trees Water supply Watershed (basins) Snowmelt Ablation Regression analysis Statistics Snow course

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