2026 Women Advancing River Research Seminar Series
Climate Impacts on Weathering and Flow
Sara Warix, University of Utah, United States
Jennifer McIntosh, University of Arizona, United States
Quantifying the various ways that climate and land use can alter water storage and transport, weathering, and biogeochemistry is critical to managing water resources. However, identifying how subsurface weathering and flow have changed in the geologic past and are continuing to change into the future is challenging due to the inherently hidden nature of the subsurface. Our talk highlights how changes in climate over long and short timescales can impact weathering, subsurface and surface flow rates and pathways, and water quality.
In the first part of this talk, we examine how modern climate change is altering geogenic weathering and stream chemistry. We identify hydrologic and biogeochemical processes most sensitive to change by comparing watershed discharge and chemistry across spatial and temporal scales—from multi-decadal (20+ year) trends across watersheds in the United States to short-term dynamics within individual watersheds. Specifically, we infer changing stream chemistry through changing streamflow source, the exposure of new reaction fronts, temperature impacts on solubility, and anthropogenic impacts such as acid rain and road salt. Overall, we emphasize the complexity of stream biogeochemistry, the value of long-term monitoring, and a need to consider the nonstationary drivers that impact stream hydrologic and biogeochemical processes.
In the second part of this talk, we will delve deeper back in geologic time to explore how fluctuations in paleoclimate altered seasonality and rates of recharge to regional aquifer systems in the semi-arid southwestern United States. Stable water isotopes, multiple age tracers, and heavy noble gases of groundwater are used to infer sources and seasonality of recharge and water table elevations from the end of the last Ice Age to the present. These natural variations are compared to human-induced changes from groundwater pumping. Furthermore, we use natural tracers to infer the flowpaths of groundwater recharge from mountain blocks via alluvial washes into adjacent basin-fill aquifers.
Bios
Sara Warix is an Assistant Professor in the Department of Geology & Geophysics at the University of Utah. She is a hydrologist and geochemist whose research examines how hydrologic and geochemical fluxes respond to climate variability, warming, and land use change. She combines field-based studies, often in mountainous headwaters, with large-scale datasets to investigate change. Sara earned her BS from the University of the Pacific, her MS from Idaho State University, and her PhD in Hydrologic Science and Engineering from the Colorado School of Mines.
Jennifer McIntosh is a Professor and the Thomas Meixner Endowed Chair in the Department of Hydrology & Atmospheric Sciences at the University of Arizona. She is a hydrogeochemist whose research uses elemental and isotope chemistry of groundwater, deep saline fluids, and natural gas to better understand the sources of solutes (including geogenic contaminants and critical mineral resources), residence times, and flow paths of fluids and gas, and biogeochemical processes from the earth’s surface to several kilometers depth. Her research group does extensive field sampling, laboratory analyses, and geochemical and hydrologic modeling. She is a fellow of GSA and the CIFAR Earth4D: Subsurface Science & Exploration Program.
All seminars will be presented online live at 11:00 a.m. ET on the third Thursday of each month. Seminar recordings will be posted later. Please register in advance for all talks.
Co-hosts: Devon Kerins, University College Dublin; Bryn Stewart, Caltech; Marguerite Xenopoulos, Trent University, Canada; Margaret Zimmer, University of Wisconsin, Madison; Li Li, Penn State