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Fasong Yuan, PhD Cleveland State University

Controls of Dryland Hydrology: Insights from Major Element and Stable Isotope Geochemistry of the Rio Grande and Pecos River. Fasong Yuan, PhD Cleveland State University Dept. of Biological, Geological, and Environmental Sciences. OUTLINE. Introduction Long-term Changes in Stream Chemistry

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Fasong Yuan, PhD Cleveland State University

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  1. Controls of Dryland Hydrology: Insights from Major Element and Stable Isotope Geochemistry of the Rio Grande and Pecos River Fasong Yuan, PhD Cleveland State University Dept. of Biological, Geological, and Environmental Sciences

  2. OUTLINE • Introduction • Long-term Changes in Stream Chemistry • Upper/middle Rio Grande • Lower Rio Grande • Pecos River • Spatial Variations in TDS • Oxygen-18 and Deuterium

  3. Introduction • Atmospheric Circulations • El Niño Southern Oscillation (ENSO) • Pacific Decadal Oscillation (PDO) • The Rio Grande Basin • Geomorphic Settings • Land Use Land Cover • Water Diversions and Water Quality • Problem Statements

  4. Atmospheric Circulations El Niño Southern Oscillation (ENSO) Normal Conditions El Niño Conditions [source: noaa.gov]

  5. Atmospheric Circulations Pacific Decadal Oscillation (PDO) warm phase cool phase [Mantua et al., 1997]

  6. Rio Grande Basin Colorado PECOS RIVER Oklahoma Arizona New Mexico Texas RIO GRANDE Mexico

  7. Land Use Land Cover [Source: rivers.txstate.edu]

  8. Dams • Elephant B., 1916 • Amistad, 1968 • Falcon, 1953 • Red Bluff, 1936

  9. Downstream Changes in Flow and TDS of the Rio Grande

  10. Flood in 1942 [source: US Forest Service]

  11. Drought in 2004

  12. Salt Crust near El Paso

  13. Salt Cedar

  14. Salt Crystals near Girvin

  15. Pecos River near Girvin in 2005

  16. (1) Approach One • Long-term changes in stream chemistry • Data Used: • International Boundary and Water Commission (IBWC), United States and Mexico • United States Bureau of Reclamation (USBR) • United States Geological Survey (USGS)

  17. Upper Rio Grande El Paso

  18. Lower Rio Grande near Amistad Amistad

  19. Lower Pecos River near Langtry, TX Langtry

  20. Upper Pecos River near Pecos, NM Pecos, NM

  21. Seasonal Change Pecos, NM Langtry

  22. Log-linear Relationship Girvin Langtry

  23. Summary • Long-term stream hydrology and chemistry are largely determined by large scale atmospheric circulations (such as PDO). • The mixed features identified in the lower valley are ascribed to • contrasting climatic settings • poor hydrologic connectivity • lithologic heterogeneity

  24. (2) Approach Two • Downstream changes in stream flow and TDS of the Pecos River • Data Used: • United States Geological Survey (USGS) • International Boundary and Water Commission (IBWC), United States and Mexico

  25. Changes in Discharge and TDS Pecos River

  26. Gibbs Model [Gibbs, 1970]

  27. Model Development [Yuan and Miyamoto, 2005]

  28. YM Model [Yuan and Miyamoto, 2005]

  29. Conversion Formula

  30. YM Model Application [Yuan and Miyamoto, 2005]

  31. Cation Changes

  32. Summary • YM model is capable of identifying mechanisms that control stream TDS. • The Pecos River receives most of the dissolved solids from the upper valley. • Evaporation is an important process regulating water chemistry. • Dilution dominates in the lower Pecos.

  33. (3) Approach Three • Characteristics of Oxygen-18 and Deuterium in the Pecos River • Data Collection • Stream Water- This Study and USGS • Precipitation- Global Network of Isotopes in Precipitation (GNIP) • Groundwater- Published Literatures

  34. d-Notation (‰)

  35. : March 7-8, 2005 : March7-8, 2005 Pecos River : July 12, 2005 : May 6-7, 2005

  36. Flagstaff, AZ Precipitation Waco, TX Chihuahua, MX [original data from GNIP]

  37. Global Meteoric Water Line (GMWL) Waco Chihuahua GW Flagstaff dD = 8d18O + 10 d = dD - 8d18O

  38. d18O and d-excess Langtry Red Bluff Santa Rosa [original data from USGS]

  39. d-excess

  40. Summary • The Pecos River contains a range of variations in d18O and dD • Although relatively large variations, the averaged values of d18O and dD of meteoric waters from the Gulf are relatively high. • d-excess (d= dD-8 d18O) appears to be a better index capable of differentiating stream waters affected by evaporative enrichments.

  41. Future Research • Speciation analysis (e.g., sulfur) • Stable isotope studies on sulfate (d34S and d18O) • Microbial analysis

  42. Acknowledgement • Martinez Ignacio and Seiichi Miyamoto of Texas A&M Research Center at El Paso • Anaya Gilbert of International Boundary and Water Commission, USA and Mexico • Alyson McDonald of Texas Cooperative Extension at Fort Stockton

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