Browsing Hydrology and Water Resources in Arizona and the Southwest, Volume 04 (1974) by Subjects
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The Effect of Development on Groundwater in the Parker StripThe 14.6 miles of the Colorado River bounded by Parker Dam and Headgate Rock Dam has been referred to as the Parker Strip. This river reach has become a high use recreation area during the past decade with 4,000 permanent residents and as many as 120,000 water enthusiasts on long weekends. The riparian area of the river is heavily clustered with mobile homes, marinas and public beaches. The means of sewage disposal is exclusively via septic tanks. Recent surveys by the Environmental Protection Agency, Arizona State Department of Public Health and the University of Arizona have localized surface water bacteria levels that may indicate a developing groundwater problem. The geohydrology of the area indicates that the septic tanks are located in Post -Pliocene Colorado River deposits. The deposits are quite thin and relatively narrow. Since the deposits are locally derived sands and gravels, the horizontal hydraulic conductivities are such that a relatively short flow time to the river may result. Intensive evaluation of the degradation of the water quality in these deposits is needed to determine if the ground water supply was jeopardized by septic tank systems.
Fresh Water for Arizona by Salt Replacement DesalinationThe process of salt replacement desalination proposed is believed to be able to produce vast quantities of fresh water be desalination. This method, which is a novel approach to minimizing the costs of saline water conversion, consists of the substitution of solutes in a solution to be desalted by a replacer chemical, and the low energy removal of that replacer chemical. The ultrafiltration of larger molecular sized replacer chemicals with high flux membranes increases the produce yield rate and reduces the corresponding energy requirement, with respect to reverse osmosis. In addition, the initial captial investment is less since no pressure constraining devices are required. The alteration of the osmotic pressure of the replacer solution within the process can also take advantage of energy savings through the utilization of an easily reversible reaction which synthesizes and breaks down a constituent that has a significant osmotic pressure difference between phases. Finally, the unusual process of fixed gel syneresis shows potential as a low energy salt replacement type process, but still requires extensive investigation.
Time-Related Changes in Water Quality of Stock Tanks of Southeastern ArizonaThis study attempts to determine the water quality changes in stock tanks and what factors are instrumental in the changes, and to assess the effects of the changes. Algal growth was the most prominent change taking place in the tanks with time. Little change in the water chemistry was noted until just before the tanks dried up. As algae died, ions tied up by the algae were released to the water, causing an increase in concentration of many of the nutrients. In order to determine the impact of various factors on algal growth, the data from eight stock tanks were analyzed by stepwise linear regression. Although 20 variables were used in the complete analysis, six variables were associated with 56.3 percent of the variance: time (since first sampling), total n, potassium, pH, inflow (recharge to the tanks), and hco3 concentration. Time and total n explained 51.3 percent of the variance, and potassium increased the variance to 52.8 percent. The pH reversed the relative positions of time and total n, with total n becoming dominant. The last two factors, inflow and hco3 were negative (resulting in a decrease in algal population) and increased the coefficient of variance to 56.3 percent.