AuthorBreed, Carol S.
AffiliationMuseum of Northern Arizona, Flagstaff
KeywordsWater resources development -- Arizona.
Hydrology -- Arizona.
Hydrology -- Southwestern states.
Water resources development -- Southwestern states.
Colorado River basin
Water allocation (policy)
Colorado River compact
Water resources development
River basin development
Central Arizona project
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RightsCopyright ©, where appropriate, is held by the author.
Collection InformationThis article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact email@example.com.
PublisherArizona-Nevada Academy of Science
AbstractSouthwestern rivers are few in numbers and low in discharge. The physiographic and climatic reasons for this are discussed. To the east of the 100th meridian, rainfall is reliable and agriculture is stable; while to the west, there is a chronic deficit of water, droughts are frequent and lifestyles must be accordingly adjusted. Dam building results in greatly increased silting behind the dam in both the river and its tributaries and accelerated channel erosion below the dam. Total flow must also decrease due to withdrawals and increased evaporation from reservoirs. The correction of apparent errors in measuring the virgin flow of the Colorado River now indicates that this flow is about 15 maf/yr. Current legal allocations total 17.5 maf/yr of river water, including the central Arizona project (cap), which will withdraw 1.2 maf/yr. While the river is being dammed and overallocated beyond all reason, the water table is being mined at the alarming rate of 20 ft/yr. In central Arizona, it has dropped to about 250 ft below the surface, and even if all withdrawals ceased immediately, it would take many centuries of of desert rains before it would return to its former level of 50 ft. The cap water will cancel only about 1/2 of this overdraft annually. A glance at the phoenix area today shows that rain follows neither the farmers plow nor the subdividers bulldozer.
Showing items related by title, author, creator and subject.
Modeling of ground-water flow and surface water/ground-water interactions of the San Pedro River Basin, Cochise County, ArizonaMaddock, Thomas, III; Vionnet, Leticia Beatriz (The University of Arizona., 1992)Ground-water exploitation in the Upper San Pedro Basin has produced the formation of a cone of depression around the Sierra Vista-Fort Huachuca area. A portion of the mountain front recharge that otherwise would reach the San Pedro River is being intercepted by pumping, and portions of baseflow are being captured by pumping. The purpose of this study is to construct a simulation model capable of simulating the ground-water system as well as the ground-water-surface water interactions. The flow simulation was done by a three-dimensional, finite-difference ground-water flow model (MODFLOW) that incorporates a new stream-aquifer interaction package. Steady state simulations were performed to represent mean annual conditions. Transient simulations cover a 48 year period, starting in 1940 and ending in 1988. A sensitivity analysis of the steady state model was also performed.
Flow and water quality relations between surface water and ground water in the Puerco River basin near Chambers, ArizonaNeuman, Shlomo P.; Van Metre, Peter Chapman, 1956- (The University of Arizona., 1990)The Puerco River is an ephemeral stream that received effluent from uranium-mine dewatering operations from the 1950's until 1962 and from 1968 until mining ceased in 1986. Flow and water-quality relations between the Puerco River and the alluvial aquifer underlying it were investigated at a site near Chambers. Data collection included installing and sampling nine monitor wells and two drive points; monitoring stage and sampling surface water; and slug testing wells. The stream recharges the alluvial aquifer during periods of flow and the streambed is a location of ground-water discharge by evapotranspiration during periods of no flow. Discharge by evapotranspiration may exceed recharge thus reducing the potential for contaminant movement away from the river by advective transport. Geochemical modeling indicates that uranium minerals are undersaturated in the range in Eh observed. A +0.84 correlation was calculated relating dissolved uranium concentration to depth in monitor wells suggesting the stream is a source of uranium to the alluvial aquifer. (Abstract shortened with permission of author.)
Populus Fremontii Tree Ring Analysis and Semi-Arid River Water Source Variability over Time, San Pedro River, ArizonaMeixner, Thomas; Stolar, Rebecca Ann; Hu, Jia; Niu, Guo-Yue (The University of Arizona., 2019)Summer floods are an important source of sustained streamflow in arid and semi-arid rivers of the American Southwest and Northwest Mexico. The degree to which natural function versus human alterations influence the system is subject to debate. Environmental information in the tree ring cellulose of Populus can be used to investigate the variation in water sources over time in these areas. Past research has shown that streamflow sources in the San Pedro Basin of Arizona vary isotopically between a source water of basin ground water and a summer flood water source. This study uses isotopic analyses of Populus fremontii and atmospheric data in the San Pedro Basin to estimate the water source of the trees and the river water source condition. After analyzing weather data within the basin, an inversion of the Barbour oxygen isotope model using tree ring cellulose isotopes was used to obtain the water source isotopic composition. The variation in water source composition inferred from the model was then compared to the river composition over time. It was initially found that each site’s water source isotopic composition was significantly different from the source water. However, several water source isotopic compositions were found to be more negative than the known basin groundwater signature in each of the study sites. Following sensitivity analyses on various parameters within the model, it was seen that relative humidity has a strong influence on the determination of source water. Therefore, relative humidity must be an accurate measurement and is not considered to be so in this study. Furthermore, in order to understand the degree to which natural function versus human alterations influence the system, older Populus fremontii tree ring isotopes are needed, posing a question regarding the reliability of the species.