From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / The Universal Soil Loss Equation (USLE) was formulated for estimating soil loss from agricultural lands in the eastern United States. It has also proven to be useful in assisting land managers make better decisions for other land uses. Studies have shown that when the equation is used in areas other than where it was developed, predictions may be inadequate due to variations in estimates of the environmental parameters used in the equation. Ten years of rainfall, runoff, and sediment yield data collected by the USDA /Agricultural Research Service were used to evaluate several cover parameter values (C) presently in use in the Southwest. Preliminary analysis of data showed no statistical differences between calculated and measured cover parameter values.

From the Proceedings of the 1983 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 16, 1983, Flagstaff, Arizona / The ground water contamination potential of the Estes Landfill, Phoenix, Arizona has been evaluated by the City of Phoenix and the Arizona Dept. of Health Services. The landfill is located in a recharge zone of the Salt River Valley aquifer. The aquifer is under water table conditions. The depth to ground water ranges from 80 feet to 15 feet. Ground water monitoring wells were installed up- gradient and down -gradient from the landfill. Ground water samples collected from the wells during flow events of the Salt River indicated leachate production from the landfill; a mound of ground water develops and intrudes the solid waste. The leachate characteristics include volatile organics and heavy metals: vinyl chloride, trichloroethylene and barium. Analysis of solid waste borings indicated only small quantities of organics and heavy metals. Currently the ground water is used for industrial and agricultural purposes. However, the ground water could be used as a domestic water supply because it has an acceptable ambient water quality. Ground water monitoring is continuing with the intent of using the data to design a leachate migration control system for the landfill and to distinguish contaminants from an adjacent landfill.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / A growing number of water providers are implementing rate structures intended to promote water conservation. The impact of an increasing block rate structure on residential water demand is examined for Tucson, Arizona. Time - series regressions on demand suggest that Tucson Water customers base consumption decisions on the previous month's average price rather than the marginal price of water. This behavior, coupled with a substantial monthly service charge, results in the rate structure discouraging, rather than encouraging, conservation. An alternate pricing structure based on distinguishing indoor and outdoor water uses is presented. Issues of economic efficiency and social equity are considered.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / A stormflow analysis was done on streamflow records from low density chaparral watersheds, located in central Arizona, that had been converted from brush to grass to determine the effect of vegetation manipulation on stormflow parameters. The Hewlett-Hibbert hydrograph separation technique was used to separate streamflow into quickflow (flashier response) and delayed flow (more controlled response). Differences in quickflow and delayed flows between treated and untreated watersheds were tested statistically by using covariance techniques based on paired watersheds. The results of the stormflow analysis showed that the conversion of brush to grass increased both quickflow and delayed flow about 30 percent. When this increase was based on an average stormflow it resulted in about a 0.04 inch rise in quickflow and a 0.01 inch rise in delayed flow. Brush to grass conversion affected the complete range of streamflows measured although the larger flows were more variable. The 30 percent increase in the quick and delayed flow components suggested that: 1) conversion produced a uniform rise in the stormflow hydrograph as opposed to affecting any single parameter, and 2) as such, produced no major changes in the runoff patterns.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / The age of ground water is defined as the length of time the water has been isolated from the atmosphere. Among the methods for ground water dating, C14 is the most commonly used and the most intensively studied tool. The concentration of C14 in dissolved inorganic carbon can change as a result of chemical processes in nature, hence, an adjustment factor Q is included in the age equation. A = QAo(e^(- λt)) Various models have been proposed to account for this adjustment factor. Among those models, the mass transferbalance approach is the most rigorous method. Wigley, Plummer, and Pearson (1978) formulated a mass balance equation to calculate the evolution of C13 and C14 in natural water systems closed to soil CO2 gas. Deines, Langmuir, and Harmon (1974) used a set of dual chemical-isotopic equilibrium equations to calculate changes of C13 in systems open to soil CO2 gas. This study implements these two models as a subroutine and adds carbon isotope mixing equations to PHREEQE (Parkhurst, Thorstenson, and Plummer, 1980), which is a computer program for general hydrogeochemical calculations. With this program package, it is now possible to simulate the evolution of chemical and carbon isotopic compositions, including C14, of ground water from open to closed systems. These simulations allow much improved inferences of Q factors for radiocarbon groundwater dating.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona

Complete issue of the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona