Rain Events and Recharge Processes in the San Luis Valley of Southern Colorado

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Academic Profile

Michelle Lanzoni is a doctoral student in the School of Geography and the Environment where she teaches on the water quality section and was a past teaching assistant for the MSc in Water Science, Policy and Management. Michelle has a BA from Prescott College in Arizona, an MS from the University of Montana in Missoula, and an MSc from the University of Oxford in Water Science, Policy and Management. Before coming to Oxford, Michelle worked in technology development for micro- and molecular-biology research laboratories in Cambridge, Massachusetts, including the Broad Institute of Harvard and MIT.

Michelle has worked on water research projects in dryland regions of the Middle East, North Africa, and the American Southwest. During her MSc at Oxford, Michelle studied groundwater recharge in Sudan. Her doctoral research investigates groundwater recharge in a high-elevation desert valley in the American West. Her current work takes place in the San Luis Valley of Southern Colorado, at the University of Oxford, and at the University of Wyoming's Stable Isotope Facility.

Research interests

  • Environmental isotopes
  • Groundwater quality
  • Water in drylands
  • Groundwater recharge
  • Precipitation chemistry

Awards and Funding

  • AGU Fall Meeting Travel Grant, Hydrology Section, 2017
  • AGU-SEG Geophysics Workshop Travel Grant, 2015
  • Rotary Global Scholarship, 2013
  • Clinton Global Initiative Award, 2010
  • Ellen Meloy Desert Writers Award, 2010

Current Research

Drylands cover roughly 40% of the Earth’s surface, and much of the groundwater in these regions was either formed during past-climate conditions or is dependent on highland hydrology. Much of the American Southwest is comprised of arid desert ecosystems whose aquifers are replenished through mountain snowmelt. Groundwater recharge through mountain block and mountain front pathways is expected to decline across much of the American Southwest due to decreased snowpack and altered timing of snowpack melt. Determining the source, timing, and chemistry of precipitation events, and how these events contribute to recharge processes is critical to understanding groundwater resources in dryland areas.

The San Luis Valley in Southern Colorado is a high-elevation agricultural desert with >1,000 m difference between valley floor and mountain pass. Snowmelt from the San Juan Mountains forms the headwaters of the Rio Grande and contributes to the valley’s groundwater. This study examines chemical and isotopic differences between precipitation that falls on the valley floor and at mountain-pass elevation. It uses chemical and isotopic tracers to identify pathways and rates of recharge to the unconfined, upper confined, and lower active confined aquifers. Water is traced through its atmospheric origin, its point of recharge, and its movement along flowpaths. This study asks, what are the main pathways for recharge, and is there evidence these recharge mechanisms may be changing over time?

To answer these questions, this study focuses on the closed basin region of the San Luis Valley, where there existed an extensive wetland playa system, which was fed by mountain creeks and groundwater inflow. This study uses isotopic tracers to investigate plant water use on the valley floor and uses time-lapse electrical resistivity to visualize water movement above the zero-flux plane. This study employs traditional and non-traditional hydrological techniques to follow water in the San Luis Valley watershed as it moves through its air-surface-ground water cycle. By placing hydrological insight within a human context, this study offers suggestions for the future stewardship of these significant groundwater resources.

Current Teaching

Selected Publications