Michelle Walvoord
(She/her)Michelle Walvoord is a Research Hydrologist in the Earth System Processes Division of the Water Resources Mission Area.
Dr. Michelle A. Walvoord is a hydrogeologist whose current research focuses on understanding hydrologic response to climate change and wildfire disturbance. With expertise in non-isothermal, multiphase subsurface flow and transport, she has led a variety of process-based vadose zone and groundwater studies in systems ranging from mid-latitude deserts to high-latitude boreal forests. Her research relies on a blend of field, statistical, and physics-based modeling approaches and typically intersects with multiple disciplines including biogeochemistry, ecology, and geophysics.
Professional Experience
Research Hydrologist, USGS Earth System Processes Division, Denver, CO (2017 – present)
Research Hydrologist, USGS National Research Program, Denver, CO (2004-2017)
National Academy of Sciences Postdoctoral Research Associate, Denver, CO (2002-2004)
Education and Certifications
Ph.D. in Earth and Environmental Science, New Mexico Tech
M.S. in Hydrology, New Mexico Tech
B.A. in Geology, Hamilton College
Affiliations and Memberships*
Affiliate Faculty, Geology and Geological Engineering Dept., Colorado School of Mines (2016 – present)
Graduate Faculty Appointment, Geological Sciences Dept., University of Colorado, Boulder (2016 – present)
Associate Faculty, Université Laval (2021 – present)
Member of the USGS Water Mission Area’s Diversity, Equity, Inclusion, and Accessibility Employee Leadership Team (2022-present)
Member of the American Geophysical Union Hydrology Section’s Justice, Equity, Diversity, and Inclusion committee (2021-present)
Board of Directors, United States Permafrost Association (2021-2022)
Associate Editor, Water Resources Research (2015 – present)
Associate Editor, Hydrogeology Journal (2014-2017)
Member of the Terrestrial Multidisciplinary distributed Observatories for the Study of Arctic Connection (t-MOSAIC) Land-Water Processes Action Group (2019 – present)
Science Steering Committee, Permafrost Action Team for the National Science Foundation’s Study of Environmental Arctic Change Project (SEARCH) (2015 – present)
Science Advisory Board, USGS Powell Center for Analysis and Synthesis (2015 – 2019)
Honors and Awards
Woo Distinguished Lecture in Hydrology, Canadian Geophysical Union, 2022
Outstanding Woman in Science Award, Geological Society of America, 2005
Langmuir Award for Excellence in Research, New Mexico Tech, 2004
Science and Products
Focused ground-water recharge in the Amargosa Desert Basin
Widespread natural perchlorate in unsaturated zones of the southwest United States
Increased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogen
Multiphase, multicomponent parameter estimation for liquid and vapor fluxes in deep arid systems using hydrologic data and natural environmental tracers
CO2 dynamics in the Amargosa Desert: Fluxes and isotopic speciation in a deep unsaturated zone
Ecohydrological control of deep drainage in arid and semiarid regions
Effects of environmental change on groundwater recharge in the Desert Southwest
Hydrologic processes in deep vadose zones in interdrainage arid environments
Enhanced gas-phase transport in a deep unsaturated zone, Amargosa Desert (U.S.A.)
Monitoring radionuclide contamination in the unsaturated zone - Lessons learned at the Amargosa Desert Research Site, Nye County, Nevada
Constraining the inferred paleohydrologic evolution of a deep unsaturated zone in the Amargosa Desert
Response to comment on "A reservoir of nitrate beneath desert soils"
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Science
- Data
- Publications
Filter Total Items: 64
Focused ground-water recharge in the Amargosa Desert Basin
The Amargosa River is an approximately 300-kilometer long regional drainage connecting the northern highlands on the Nevada Test Site in Nye County, Nev., to the floor of Death Valley in Inyo County, Calif. Streamflow analysis indicates that the Amargosa Desert portion of the river is dry more than 98 percent of the time. Infiltration losses during ephemeral flows of the Amargosa River and FortymiAuthorsDavid A. Stonestrom, David E. Prudic, Michelle Ann Walvoord, Jared D. Abraham, Amy E. Stewart-Deaker, Patrick A. Glancy, Jim Constantz, Randell J. Laczniak, Brian J. AndraskiWidespread natural perchlorate in unsaturated zones of the southwest United States
A substantial reservoir (up to 1 kg ha-1) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10−15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to tAuthorsBalaji Rao, Todd A. Anderson, Greta J. Orris, Ken A. Rainwater, Srinath Rajagopalan, Renee M. Sandvig, Bridget R. Scanlon, David A. Stonestrom, Michelle Ann Walvoord, W Andrew JacksonIncreased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogen
Arctic and subarctic watersheds are undergoing climate warming, permafrost thawing, and thermokarst formation resulting in quantitative shifts in surface water - groundwater interaction at the basin scale. Groundwater currently comprises almost one fourth of Yukon River water discharged to the Bering Sea and contributes 5-10% of the dissolved organic carbon (DOC) and nitrogen (DON) and 35-45% of tAuthorsMichelle Ann Walvoord, Robert G. StrieglMultiphase, multicomponent parameter estimation for liquid and vapor fluxes in deep arid systems using hydrologic data and natural environmental tracers
Multiphase, multicomponent numerical models of long-term unsaturated-zone liquid and vapor movement were created for a thick alluvial basin at the Nevada Test Site to predict present-day liquid and vapor fluxes. The numerical models are based on recently developed conceptual models of unsaturated-zone moisture movement in thick alluvium that explain present-day water potential and tracer profilesAuthorsEdward M. Kwicklis, Andrew V. Wolfsberg, Philip H. Stauffer, Michelle Ann Walvoord, Michael J. SullyCO2 dynamics in the Amargosa Desert: Fluxes and isotopic speciation in a deep unsaturated zone
Natural unsaturated-zone gas profiles at the U.S. Geological Survey's Amargosa Desert Research Site, near Beatty, Nevada, reveal the presence of two physically and isotopically distinct CO2 sources, one shallow and one deep. The shallow source derives from seasonally variable autotrophic and heterotrophic respiration in the root zone. Scanning electron micrograph results indicate that at least parAuthorsMichelle Ann Walvoord, Robert G. Striegl, David E. Prudic, David A. StonestromEcohydrological control of deep drainage in arid and semiarid regions
The amount and spatial distribution of deep drainage (downward movement of water across the bottom of the root zone) and groundwater recharge affect the quantity and quality of increasingly limited groundwater in arid and semiarid regions. We synthesize research from the fields of ecology and hydrology to address the issue of deep drainage in arid and semiarid regions. We start with a recently devAuthorsM.S. Seyfried, S. Schwinning, Michelle Ann Walvoord, W. T. Pockman, B.D. Newman, R.B. Jackson, F. M. PhillipsEffects of environmental change on groundwater recharge in the Desert Southwest
Climate and other environmental conditions have varied in the past, and will almost certainly vary significantly in the near future. The response of groundwater recharge to changes in environmental conditions is thus a matter of active concem for water-resources management. The major mechanisms for this response of recharge are three-fold. First, changes in vegetation communities can shift the watAuthorsFred M. Phillips, Michelle Ann Walvoord, Eric E. SmallHydrologic processes in deep vadose zones in interdrainage arid environments
A unifying theory for the hydrology of desert vadose zones is particularly timely considering the rising population and water stresses in arid and semiarid regions. Conventional models cannot reconcile the apparent discrepancy between upward flow indicated by hydraulic gradient data and downward flow suggested by environmental tracer data in deep vadose zone profiles. A conceptual model describedAuthorsMichelle Ann Walvoord, Bridget R. ScanlonEnhanced gas-phase transport in a deep unsaturated zone, Amargosa Desert (U.S.A.)
No abstract available.AuthorsMichelle Ann Walvoord, David A. StonestromMonitoring radionuclide contamination in the unsaturated zone - Lessons learned at the Amargosa Desert Research Site, Nye County, Nevada
Contaminant-transport processes are being investigated at the U.S. Geological Survey’s Amargosa Desert Research Site (A DRS), adjacent to the Nation’s first commercial disposal facility for low-level radioactive waste. Gases containing tritium and radiocarbon are migrating through a 110-m thick unsaturated zone from unlined trenches that received waste from 1962 to 1992. Results relevant to long-AuthorsDavid A. Stonestrom, Jared D. Abraham, Brian J. Andraski, Ronald J. Baker, C. Justin Mayers, Robert L. Michel, David E. Prudic, Robert G. Striegl, Michelle Ann WalvoordConstraining the inferred paleohydrologic evolution of a deep unsaturated zone in the Amargosa Desert
Natural flow regimes in deep unsaturated zones of arid interfluvial environments are rarely in hydraulic equilibrium with near-surface boundary conditions imposed by present-day plant–soil–atmosphere dynamics. Nevertheless, assessments of water resources and contaminant transport require realistic estimates of gas, water, and solute fluxes under past, present, and projected conditions. MultimillenAuthorsMichelle Ann Walvoord, David A. Stonestrom, Brian J. Andraski, Robert G. StrieglResponse to comment on "A reservoir of nitrate beneath desert soils"
We appreciate the comment by Jackson et al. (1), which underscores two points made in our recent paper (2): (i) that desert subsoil nitrate (NO–3) inventories are spatially highly variable, and thereby warrant substantial measurement efforts to reduce uncertainty in global extrapolations, and (ii) that Chihuahuan Desert subsoil NO–3 inventories tend to be much smaller than inventories in other wesAuthorsMichelle Ann Walvoord, Fred M. Phillips, David A. Stonestrom, R. Dave Evans, Peter C. Hartsough, Brent D. Newman, Robert G. StrieglNon-USGS Publications**
Walvoord, M.A., 2002, A Unifying Conceptual Model to Describe Water, Vapor, and Solute Transport in Deep Arid Vadose Zones, Ph.D. thesis, New Mexico Institute of Mining and Technology, Socorro, NM, 297 p.Hartsough P.C., S.W. Tyler, J. Sterling, M.A. Walvoord, 2001, A 14.6 kyr record of nitrogen flux from desert soil profiles as inferred from vadose zone pore waters, Geophysical Research Letters, 28, 15, 2955 - 2958.Walvoord, M., P. Pegram, F. Phillips, M. Person, T. Kieft, J. Fredrickson, J. McKinley, J. Swenson, 1999, Groundwater flow and geochemistry in the southeastern San Juan Basin: Implications for microbial transport and activity, Water Resources Research, 35, 1409 – 1425.Walvoord, M., 1998, Characterization of Groundwater Flow in the Southeastern San Juan Basin: Implications for Microbial Origins in the Deep Subsurface Near Cerro Negro, New Mexico, MS thesis, New Mexico Tech, Socorro, NM, 142 p.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
- News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government