Browsing Hydrology and Water Resources in Arizona and the Southwest, Volume 11 (1981) by Issue Date
Now showing items 1-20 of 36
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Aspects of Aquifer Test Error AnalysisErrors in the estimation of the aquifer parameters T and S derived from aquifer test data are examined as to their cause and effects. The analysis is based on the Theis equation. The basic causes of error are in the measurements of drawdown and pumping rate, in fitting the model to the data and in violations of model assumptions. Measurement errors were studied experimentally. Curve fittings by hydrologists were compared to "automatic" curve fittings obtained by nonlinear regression. The covariance matrix of T and S obtained in this manner was used, in conjunction with sensitivity analysis, to estimate the error in prediction of future drawdown. While automatic fitting is not a perfect substitute for graphical fitting, there is a definite relation between the two methods which allows the use of the statistics developed by nonlinear regression theory to be used to study the cause, effects and risks inherent in aquifer analysis.
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The Alternatives and Impacts Associated with a Future Water Source Transition for Tucson WaterAnticipating a surge in the future growth of the Tucson urban area accompanied by a need for the preservation of the local groundwater resource, Tucson Water is planning for a major transition in its source of supply during the next fifty years. The completion of the Central Arizona Project to the Tucson area represents the primary ingredient to the formulation of a future water supply plan for the community. Tucson, which presently relies totally upon groundwater for its potable water supply, is diligently preparing to accept its first surface water source. The task of planning for this event is extremely complex and is further hampered by the fact that many critical factors relating to the Tucson Division of the Central Arizona Project are yet undefined. Tucson Water engineers utilize contemporary computerized hydraulic models as tools to define an array of technical solutions to the problem of accomplishing a major conversion from a multi-point system source to a predominantly single source of supply. Elements such as construction, operation, and maintenance costs associated with water treatment and delivery systems are addressed.
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Water Yield Opportunities on National Forest Lands in ArizonaWater Yield improvement opportunities were estimated for National Forest lands in Arizona. The land base available for treatment was reduced in a stepwise manner to account for administrative, climatic, and ownership constraints. Research relationships were built upon, and then applied to the remaining land base to project water yield estimates. A continuum of management prescriptions was then displayed to show the range of opportunities. Only the chaparral, ponderosa pine, and mixed conifer types show opportunities of significance. Water yield increases can be realized principally from conversion of chaparral to grass and could add an additional 25 to 70 thousand acre-feet. The ponderosa pine zone could add an additional 15 to 30 thousand acre-feet with intensive management by reducing stocking levels on the commercial National Forest lands. Little opportunity exists within the mixed conifer zone and increases would amount to less than 10 thousand acre -feet. Annual contributions of National Forest lands are likely to range from 40 thousand to 100 thousand acre feet; this will be highly variable depending upon precipitation quantities.
