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Alex Rinehart, PhD

Assistant Professor

Earth and Environmental Science

I study how water and soil and rocks interact, with focuses on using surface deformation and changes in gravity can be used to understand subsurface water movement, the mechanisms of water and chemical weakening on rock strength and progressive rock failure, and on various applied hydrogeologic and vadose zone projects. I have worked as an assistant professor here at NMT since 2019.
 
Funded position: Currently seeking a M.S. student to begin in Fall 2023 focused on vadose zone hydrology. The student will explore how climate change-driven land-use changes the water balance at the farm scale.  This work will involve monitoring soil moisture and soil water potential in farms in the High Plains of eastern New Mexico, as well as measuring water holding capacity and soil organic carbon in active fields, recently fallowed land (likely a future pathway), and land that hasn't been farmed for 50+ years. Combined with estimating groundwater changes and evapotranspiration, the student will answer questions about likely changes in the farm-scale water balance under different climate change pathways. She will also inform water-constrained economic models built by collaborators.
 
 
Career path:
 
I completed a BS in Mathematics (UNM), followed by a MS in Hydrology (NMT) and a PhD in Earth Sciences (emphasis in Geophysics, NMT). My PhD work was completed as a graduate intern in the Geomechanics Department at Sandia National Labs, an incredible experience of working on basic science in outstanding service to the country and world. I then served as a hydrogeologist at the New Mexico Bureau of Geology for five years. At the Bureau, I worked on hydrogeologic studies for small communities, state-wide assessments of groundwater storage change and natural hazards, and supporting experimental work understanding carbon capture and underground storage.
 
To be able to mentor young people, I became an assistant professor in 2019. I have spent my life in New Mexico, but intellecutally have moved across disciplines within the earth sciences.
 
Research:
 
My research crosses hydrology, geophysics and rock mechanics to understand applied hydrologic questions, hydrogeodesy, reservoir and geothermal coupled processes, and the role of water and fracture in landscape development. 
 
Applied hydrology
Currently, my group is working on understanding basin-scale sources of groundwater using environmental tracers and water chemistry (student: Ethan Williams), and on measuring hydrologic properties of soils to understand how climate change will alter the water balance (student: Kyle Gallant).
 
This work is field and lab intensive. The groundwater studies involve measurement of groundwater levels, surface water flow, collection of water quality samples and analysis of the water quality samples. By doing integrated surveys, we can understand the different ways groundwater and surface water are connected.
 
Research in the vadose zone largely consists of opening and describing soil pits, followed by laboratory analysis of physical, chemical and hydrologic properties. This work is supporting ecosystem climate manipulation experiments at the Sevilleta Long-Term Ecological Research station.
 
Hydrogeodesy
Normal hydrologic approaches either use direct measurements of groundwater levels to understand aquifers usually at single points, or use water quality methods such as stable water isotopes, groundwater age dating, or general chemistry to indirectly understand how the larger system works.
 
Hydrogeodetic techniques, which link surface deformation measured by GPS or satellite, or small changes in gravitational acceleration to changes in water storage in aquifers, hold the promise to revolutionize how we understand water movement in the subsurface. Because they average over large areas, single sets of measurement can tell you how an entire portion of an aquifer or watershed behaves--even up to entire mountain ranges.
 
Currently, I am performing repeat gravity surveys on land to understand focused recharge supporting Dan Cadol, and working with researchers at UA-Fairbanks on using satellite-based deformation mesurements (InSAR) to understand groundwater changes across all of New Mexico. I am also supporting work at NMT using tiltmeters to understand flow in karst conduits in Florida.
 
This work combines data analysis, modeling, and field deployments; something for everyone. The repeat gravity work requires someone who can do extremely careful, detailed field work. The measurements are on the edge of the current instrumentational limits.
 
 
Environmental progressive rock failure
Recent research has shown that the water-mediated fracturing at the surface controls the rate of mechanical weathering and water movement in bedrock regions. The previous paradigm was that fracture occured at a critical (high) stress. Now, we believe that fracturing happens during thermal fatigue and chemically controlled stress corrosion fracture. This means that 'standard' rock properties may not predict the mechanical weathering of rocks and landforms. Rather, subcritical fracture properties--mostly mediated by salts and water--will.
 
This work is done in collaboration with geomorphologists, geomechanicians, hydrologists and engineers, linking land surface ages to rock properties via measurements and models. My group is focused on performing laboratory testing of rocks under controlled environmental conditions, providing key observations of process and properties to inform geomorphic interpretations.
 
We are currently performing tests in collaboration with UNC-Charlotte and Colombia University focused on mechanical weathering in hyper-arid, frozen environments.
 
Thermo-hydraulic-mechanical-chemical processes in subsurface energy
We are answering questions of how to predict how fluids like water, CO2 and hydrogen interact with each other and rocks. These questions are vital for current effort of climate change mitigation. Pursued experimentally, we run extended experiments simulating reservoir conditions with as we push different fluids through rocks and monitor changes in chemistry, strength and permeability. This information is then used by modelers and engineers to understand if a system is appropriate as a storage reservoir or as a geothermal resource.
 
This work is laboratory intensive, with the student performing high-pressure and high temperature experiments measuring hydraulic and mechanical properties, performing chemical analysis, and using petrographic (thin section) observations to understand what happened to the samples.
 
Current projects include supporting DOE CarbonSafe projects, the DOE Southwest Carbon Sequestration Partnership, and DOE-funded research on rare-earth elements in coal. We are actively seeking projects in CCUS, hydrogen storage and geothermal.
 
 
 
 
Teaching:
  • GEOL 440: Hydrological Theory and Field Methods
  • HYDR 514: Vadose Zone Hydrology
  • HYDR 555: Rock Fracture in Geologic Settings
  • HYDR 556: Natural Complexity
  • HYDR 558: Environmental Tracers in Hydrology
  • GEOL 482 / HYDR 572: Special Topics: Engineering Geology
  • GEOP 505 / MATH 587: Time Series Analysis
 
 
Current Group Members:
 
Andrew Luhmann (Wheaton College, assistant professor)
Ronni Grapenthin (University of Alaska - Fairbanks, assistant professor )
 
Sai Wang (research associate, PRRC)
Robert Czarnota (research associate, PRRC)
Jason Simmons (research associate, PRRC)
 
Ethan Williams (MS, Hydrology, E&ES, NMT)
Marissa Fichera (PhD, Hydrology, E&ES, NMT, beginning Spring 2023)
Kyle Gallant (BS, Geology, E&ES, NMT)
Antonio Chavez (BS, Environmental Science, E&ES, NMT)
 
Emily Graves (PhD, Geophysics, UAF)
 
 
Graduated Group Members:
 
Samuel Otu (MS, Hydrology, E&ES/PRRC, NMT)
Jason Simmons (MS, Hydrology, E&ES/PRRC, NMT, now a research associate at PRRC)
Zhidi Wu (MS, Hydrology, E&ES/PRRC, NMT, Luhmann was advisor)
 
 
CV via Google Doc