HR: 1340h
AN: H53A-0959    [Abstracts]
TI: Ground-Water Sources, Flow-Paths, and Residence Times in the Middle Verde River Watershed, Northern Arizona
AU: * Zlatos, C M
EM: cmzlatos@hwr.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona, Harshbarger Building, 1133 E. James E. Rogers Way, Tucson, AZ 85721, United States
AU: Hogan, J F
EM: jhogan@hwr.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona, Harshbarger Building, 1133 E. James E. Rogers Way, Tucson, AZ 85721, United States
AU: Blasch, K W
EM: kblasch@usgs.gov
AF: U.S. Geological Survey, DeConcini Building, 520 North Park Avenue, Tucson, AZ 85719, United States
AU: Bills, D J
EM: djbills@usgs.gov
AF: U.S. Geological Survey, Arizona Water Science Center, Flagstaff Programs, 2255 N. Gemini Dr. Bldg. 3, Flagstaff, AZ 86001, United States
AU: Meixner, T
EM: tmeixner@hwr.arizona.edu
AF: Department of Hydrology and Water Resources, University of Arizona, Harshbarger Building, 1133 E. James E. Rogers Way, Tucson, AZ 85721, United States
AB: Geochemical tracers serve as valuable tools for characterizing basin hydrogeology. By combining stable and radioactive isotopic analyses with solute concentrations and discharge data, one can constrain hydrologic flow- paths and water sources in an area of complex hydrogeology. These techniques are applicable to the Middle Verde River watershed, a region located in the transition zone between the Southern Colorado Plateau and the Basin and Range structural provinces. As the population within the Verde River Valley is projected to double by 2050, efforts to improve the conceptual understanding of basin hydrogeology and to quantify recharge rates within the watershed are critical for water resources management. The primary objective of the investigation is to determine the hydrologic connection between aquifers underlying the Colorado Plateau and adjacent aquifers in the Verde River watershed through analysis of oxygen and hydrogen stable isotopes, tritium, carbon-14, and major solute concentrations. The secondary objective is to gain an understanding of how these water sources and flow-paths contribute to and sustain Verde River base-flow. Two surface-water datasets collected from the Middle Verde River and its tributaries (Oak Creek, Wet Beaver Creek, and West Clear Creek) in November 2006 and June 2007 serve as snapshots of winter and summer base-flow conditions, respectively. Ground-water samples complement these datasets by serving as end members for base-flow source mixing models. Preliminary analyses based on solute relationships (i.e. chloride- sulfate and bromide-chloride) show evidence of separate solute sources for the Verde River and its tributaries. The distinct Verde River trends, including overall increases in solute concentrations along two reaches (kilometers 15 to 30 and 57 to 66, as measured upstream from USGS gauge 09506000), suggest dissolution of evaporite deposits within the Tertiary lakebed-derived Verde Formation. Notably, ground-water from wells drilled in the Verde Formation near the Verde River is geochemically more similar to surface-water from the river's tributaries than to the river itself. This suggests that the Verde Formation is supplied by waters from the surrounding formations and this water then undergoes evolution based on the geologic variability of the Verde Formation. Seasonal sources of base-flow are constrained by oxygen and hydrogen stable isotope values: mixing models using regional precipitation averages as end members show greater contribution of winter precipitation than summer precipitation.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1829 Groundwater hydrology
DE: 1830 Groundwater/surface water interaction
DE: 1860 Streamflow
SC: Hydrology [H]
MN: 2007 Fall Meeting