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 / Arizona's water resources system consists primarily of four active management areas (Tucson, Phoenix, Pinal and Prescott), the Central Arizona Project, and the Salt River Project. The problem of water allocation among user categories involves pumping from aquifers and diversions of surface flows. In systems less complex than Arizona, allocation policies may appear obvious. In this case, however, a two-level hierarchical management model is proposed to control water allocation to users: the active management areas as a lower echelon, and the Arizona Department of Water Resources at the higher level. A system theoretic approach combined with recent developments in the decentralized control theory are proposed to be included in the model. A significant characteristic of the proposed model is the ability to consider possible interactions among the active management areas as a result of policy decisions at the State level. A dynamic optimization model based on a state space formulation with total energy required as the objective function is solved for each of the subsystems. Detailed information thus generated at the regional level is then appropriately aggregated for statewide decision making. An iterative algorithm is suggested.

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 / Chlorine-36 is an important radioisotope with which to date old ground water. The initial chlorine-36 in ground water originates in the atmosphere by cosmic ray spallation of argon-40. Following precipitation and infiltration processes, the natural decay of this radioisotope is then used to date ground water. One must consider, however, the production of chlorine-36 in the subsurface. The production reaction of most interest is ³⁵C1 + neutron → ³⁶C1 + gamma. Buildup of chlorine-36 in the subsurface can result from cosmic ray secondary neutrons near the surface and natural radioactivity produced neutrons below the surface. These production mechanisms, if not taken into consideration, will contribute to the error in chlorine-36 age determinations. To predict subsurface production rates, field measurements were made of thermal neutron fluxes for various geologic materials and depths below the surface. Thermal neutron fluxes were found to vary by more than three orders of magnitude. Theoretical calculations of neutron flux were compared to filed measurements. Estimates of chlorine-36 production rates were then calculated and compared to measured values of chlorine-36 in very old ground water, where decay rates have been hypothesized to be equal to production rates.

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 relative importance of mountain front recharge as compared to total recharge was determined for a portion of the Tucson basin aquifer margin by interpretation of chemical and isotopic data. Concentrations of 180/160 lower than 6 -10.7 ⁰/00 as compared with a background of about 6 -9.3 ⁰/00 in ground water from the base of the mountains in the gneissic rock suggest the presence of recharge from significantly higher elevations. The trilinear diagram of major ions dissolved in ground water from 123 wells in the Santa Catalina foothills indicates three water types. Water from wells in gneissic rock is high in sodium and potassium content and low in calcium and magnesium. Wells in the gypsiferous Pantano Formation yield water high in sulfates. The majority of wells in the study area, which are along major streams and in the regional aquifer, have calcium carbonate type water. Their chemistry indicates only minor contributions from the gneissic mountain block and the underlying Pantano Formation. Funding for this project came from the Spanish Project Register T377017.

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 Tucson Airport Super Fund Area is currently being investigated by the Environmental Protection Agency, the Arizona Dept. of Health Services, the City of Tucson and the Arizona Dept. of Water Resources for volatile organics and heavy metal ground water contamination. The volatile organics include trichloroethylene (TCE), trichloroethane (TCA), dichloroethylene (DCE) and heavy metals, primarily chromium. The area is defined as north of Los Reales Rd. to distinguish this contamination from the US Air Force Plant No. 44 contamination south of Los Reales Rd. The investigation includes defining the hydrogeology, the extent of ground water contamination and potential contamination sources. The aquifer being contaminated is located in the Upper Santa Cruz Basin and is the principal source of domestic water for the City of Tucson. The area of concern currently contains 177 water wells; 24 of these wells are contaminated with TCE concentrations ranging from 5 ug /1 to greater than 400 ug /l. This includes 6 City of Tucson public supply wells. There are currently 6 potential contamination sources being investigated. The first phase of Super Fund will enable the State and City governments to collect and analyze data which will be used for remedial action.

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 Upper Santa Cruz Basin Mines Task Force implemented a two year groundwater monitoring program in response to recommendations of an earlier investigation. The work program included monitoring several copper mines' tailing ponds and wells 15-20 miles south of Tucson. ASARCO mine was monitored to determine the source of high sulfates and TOS in the groundwater in the vicinity of the ASARCO ponds. A network of twelve sampling sites was sampled quarterly to look at water quality trends over time. One additional monitor well was drilled at the base of ASARCO's newest pond. The Anamax groundwater monitoring program consisted of investigating changes in water levels and water quality in the vicinity of its two tailing ponds to determine the hydrologic impacts of the ponds. The Duval program consisted of a network of thirteen monitor and seven interceptor wells. It was designed to determine the effectiveness of the interceptor wells as a management practice for preventing migration of mineralized tailing pond seepage to downgradient areas. The programs are compared in relation to their relative merits and their effectiveness in determining the groundwater quality impacts of the tailings ponds.

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

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

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 / Understanding residential water uses is important for forecasting water demand. Data from survey questionnaires received from over 2000 Tucson Water customers are used to analyze individual household water use patterns. Earlier findings by the authors based on aggregate census data are verified and expanded. Initial findings indicate that both indoor and peak outdoor water demand, modeled separately, are determined by three factors. The factors are categorized as 1) a demographic component, describing the number of people in the household and their ages, 2) a wealth component, relating water consumption to income, home value and certain appliance ownership, and 3) a residency component, which includes the age of the home, length of time the household has lived in the home, and length of time the household has lived in the Tucson area. Regression analysis indicates that households newer to Tucson consume less water than otherwise similar households. The analysis also shows that an average swimming pool consumes substantially more water than a lawn of equal area. Two actions resulting in reduced indoor water consumption are installing low-flow plumbing devices and directly paying the water bill. Water conservation program strategies based upon these findings are summarized.

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