From the Proceedings of the 1977 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 15-16, 1977, Las Vegas, Nevada / Phreatophyte transpiration on the Colorado River floodplain in western Arizona was evaluated under hot, dry, midsummer weather conditions. The simple transpiration model used related transpiration to the vapor pressure deficit of the air and to the area and the diffusion resistance of the transpiring foliage. There were no independent transpiration measurements for verification of the results. On a relative basis, however, mesquite (Prosopis sp.) transpired more rapidly per unit of leaf area than did saltcedar (Tamarix chimensis, Lour.).

From the Proceedings of the 1977 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 15-16, 1977, Las Vegas, Nevada

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / A discrete stochastic multistage decision model is developed, in the framework of which the dynamic programming algorithm is defined. It is demonstrated that the algorithm may be used as a solution procedure for non-routine reservoir control problems. The study demonstrates that analytical considerations may be used to significantly reduce the amount of computation needed for the implementation of the algorithm. Two reservoir control problems are studied: The "reliability problem" in which one seeks a minimum-cost operation rule under a constraint which specifies the maximum probability of shortage allowed during the life-time of the project, and the "range problem" in which the objective is the minimization of the expected value of the range of fluctuation around a critical storage level.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Strip mining leaves behind spoils to be recontoured to maximize the benefit of livestock production on the rehabilitated land. This paper designs watersheds to achieve a balance between two main range livestock requirements, forage and stock water by way of grading and furrowing man-made slopes. The three design attributes, surface configuration, surface treatment, and range management policy are optimized with respect to maximal profit accounting for natural uncertainties in 3 variables, viz., time interval between storm arrivals, precipitation per storm event, and duration of the storm event. Runoff and sedimentation are modeled on an event basis as functions of said random variables. The stock water reservoir at the bottom of the watershed is dredged periodically. The stochastic model is applied to the Black Mesa in Northern Arizona which is in the process of being strip-mined for coal.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Osmosis occurs when two solutions of differing osmolar concentrations are separated by a membrane permeable to the solvent but not (or nearly not) to the solutes. This paper derives the relationship between the kinetics and design parameters of systems designed for the purpose of applying this process to problems such as agricultural water reclamation, dehydration of solutions and the production of potable nutrient solutions from sea water. Three mathematical models that include increasingly complex fundamental process assumptions are presented. In all cases the fundamental mechanical device is assumed to be a continuous flow extractor that incorporates a semipermeable membrane.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Solar powered pumping is technically feasible. However, solar energy intensity is variable and its collection requires high capital investment. Present production methods might require modification for most economic use of solar energy. Various irrigation and pumping practices are examined to determine those most compatible with use of solar power. The tentative conclusion of the study is that solar energy usage is most economical for driving pumps only during sunlight hours and where pumping requirements are uniform throughout the year. Solar energy is a more costly source of pumping power than electricity or natural gas.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona

From the Proceedings of the 1977 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 15-16, 1977, Las Vegas, Nevada / In contrast to three ephemeral streams in the vicinity, Tony Bear Creek, a small perennial stream in the White Mountains of Arizona, showed strong relationships among parameters of hydraulic geometry. Distances between gravel bars and log steps showed an inverse relationship with gradient (r² = 0.95). Shape factor and width-depth ratio increased upstream (r² = 0.98 and 0.90, respectively), indicating depth decrease toward the headwaters. The longitudinal profile is concave, and small, infrequent channel bars suggest that sediment movement is small. In contrast to the ephemeral streams, Tony Bear Creek is thus judged to be in dynamic equilibrium. Proportion of log steps to total steps (gravel bars plus logs) was much smaller in Tony Bear Creek (about 16 %) than in five other mountain streams (about 50 %). While all other streams ran through dense forests, only 60% of Tony Bear Creek was in forest, of which 13% had been selectively cut. Thus, forest density determined the proportion of logs incorporated into the stream hydraulic system, which in turn affects bedload movement.