HR: 0830h
AN: H21B-06    [Abstracts]
TI: Geochemical Classification of Groundwater Salinization in the Northern Hueco Bolson Aquifer
AU: * Druhan, J
EM: jenny@hwr.arizona.edu
AF: SAHRA Sustainability of semi-Arid Hydrology and Riparian Areas, SAHRA (5th floor) P.O. Box 210158-B, Tucson, AZ 85721-0158 United States
AU: * Druhan, J
EM: jenny@hwr.arizona.edu
AF: University of Arizona Department of Hydrology and Water Resources, 1133 E. North Campus Drive Harshbarger Building P.O. Box 210011, Tucson, AZ 85721 United States
AU: Eastoe, C
EM: eastoe@geo.arizona.edu
AF: SAHRA Sustainability of semi-Arid Hydrology and Riparian Areas, SAHRA (5th floor) P.O. Box 210158-B, Tucson, AZ 85721-0158 United States
AU: Eastoe, C
EM: eastoe@geo.arizona.edu
AF: University of Arizona Department of Hydrology and Water Resources, 1133 E. North Campus Drive Harshbarger Building P.O. Box 210011, Tucson, AZ 85721 United States
AU: Hogan, J
EM: hogan@hwr.arizona.edu
AF: SAHRA Sustainability of semi-Arid Hydrology and Riparian Areas, SAHRA (5th floor) P.O. Box 210158-B, Tucson, AZ 85721-0158 United States
AU: Hogan, J
EM: hogan@hwr.arizona.edu
AF: University of Arizona Department of Hydrology and Water Resources, 1133 E. North Campus Drive Harshbarger Building P.O. Box 210011, Tucson, AZ 85721 United States
AU: Hibbs, B
EM: bhibbs@calstatela.edu
AF: California State University at Los Angeles Department of Geological Sciences, Geological Sciences PS216 5151 State University Drive, Los Angeles, CA 90032 United States
AU: Hibbs, B
EM: bhibbs@calstatela.edu
AF: CEA-CREST, Biological Sciences BS140 5151 State University Drive, Los Angeles, CA 90032 United States
AU: Hutcheson, B
AF: El Paso Water Utilities, P.O. Box 511, El Paso, TX 79961-0001 United States
AB: The Hueco Bolson aquifer is the primary water resource for the cities of El Paso and Juarez. Identification of the primary groundwater recharge zones and the dynamics of salinization are needed in order to predict the impact of current and future development of water resources. Excessive withdrawal has resulted in a persistent increase in salinity, forcing the El Paso Water Utility (EPWU) to abandon several once highly productive wells. The mechanisms for this pumping induced salinization are not clear, but may include upward movement of deep saline groundwaters, lateral migration of saline waters from elsewhere in the aquifer and pumping induced leakage of saline waters from mud and clay layers. Isotopic and chemical analysis of groundwaters from a recently constructed well field with multiple discrete vertical zone samples has provided a unique opportunity to characterize these deep salinity sources and identify the primary mechanisms of pumping induced salinization. Analysis of O and H isotopes was used to delineate two primary recharge zones in the northern portion of the aquifer. The western section along the Franklin Mountains indicates a linear trend of oxygen/hydrogen isotope ratios indicative of mountain front recharge with highly evaporated waters at depth. The eastern portion closer to the center of the basin shows a more complex picture of shallow and deep evaporated waters, with a mixing zone of a less evaporated source at intermediate depth. Incorporation of anion ratios and S isotope data with that of these recharge zones indicates multiple sources of salinization. High anion ratios and S isotope values characteristic of deep saline waters appear at depths greater than 300 meters, with S isotope values higher than 9‰ and Cl/Br ratios greater than 10,000. Mixing trends of these highly saline deep waters appear at the lowest intervals of some wells above 300 meters, indicating upward movement of deep saline groundwaters as a possible source of increased salinity. Additionally, data from shallow well intervals and less evaporated mountain front waters show a range of anion and sulfur isotope signatures distinct from those of the deep saline waters (e.g. S isotopes 4 to 9‰ and Cl/SO4 ratios of 200-8000). This range of values and their distributions with depth suggest multiple salinity sources in addition to the deep saline waters. Ultimately, this understanding of recharge and salinity sources will be incorporated into the EPWU groundwater model, which will aid in determining strategies that reduce pumping-induced salinization of the aquifer.
DE: 1040 Isotopic composition/chemistry
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2005 Joint Assembly