The John Joly Memorial Lecture 2026
Reserve your free ticket via Eventbrite: The John Joly Memorial Lecture 2026
Venue: Physics Lecture Theatre
Time: 17.00-18.00
Guest Lecturer: Prof Bridget R. Scanlon is Research Professor (The Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin.)
Lecture Title: Aquifers as Buffers Against Global Water Stress.
Prof Bridget R. Scanlon is Research Professor at the Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin.
Biography
Bridget Scanlon is a world-renowned hydrogeologist and Research Professor at the Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin. Her current research focuses on various aspects of water resources, including assessments using satellite data and modelling, management related to climate extremes, and water energy interdependence. She is particularly interested in adaptation strategies for managing climate extremes by storing flood waters in depleted aquifers for use during droughts. She has authored or co-authored ~200 publications. She is a Fellow of the American Association for the Advancement of Science, American Geophysical Union, and Geological Society of America and a member of the US National Academy of Engineering. Wonderfully and completely unrelated to our invitation to her being the 2026 Joly Seminar speaker, she earned a bachelor’s degree in geology at Trinity College Dublin.
She will deliver the John Joly Memorial Lecture on the topic of Aquifers as Buffers Against Global Water Stress.
Lecture will be followed by wine and cheese reception from 6pm - 8pm in the Main Foyer, Museum Building, on Trinity's Main Campus
Abstract
Population growth, urbanization, rising demand, and frequent, severe droughts are increasing pressure on water supplies. Groundwater serves as a critical buffer to surface-water supplies, much like a savings account that sustains availability when the surface-water “checking account” is depleted. Yet many aquifers are being depleted, particularly in semi-arid regions where irrigation and population growth depend on them. The question is therefore not only how much groundwater remains, but whether aquifers can also provide storage for water available at other times or in other places.
I examine global changes in total water storage using observations from GRACE satellites together with land-surface deformation measured by radar satellites. Considered together, these observations help identify regions where groundwater storage is declining, stable, or rising. Substantial water-storage losses occur in major hotspots, including the southwestern and south-central United States, northwestern India, the Middle East and North Africa, and the North China Plain. In contrast, stable or rising trends are evident in parts of the northwestern United States, Argentina, and sub-Saharan Africa. In semi-arid regions, declining storage is largely associated with groundwater irrigation. In the southwestern United States, InSAR observations of land subsidence indicate that prolonged groundwater depletion has resulted in ~10–15% permanent loss of aquifer storage capacity. Rising storage trends are often associated with wet climate episodes, land-use change from native, deep-rooted vegetation to shallower-rooted crops, and/or surface-water irrigation that enhances recharge.
These syntheses reveal an important opportunity: many regions experiencing groundwater depletion contain large subsurface reservoirs with remaining capacity to store water. Partially depleted aquifers can therefore serve as water-storage infrastructure through Managed Aquifer Recharge (MAR), reducing evaporative losses from surface reservoirs while increasing water-supply resilience. A fundamental challenge is obtaining and delivering suitable recharge water, particularly in semi-arid regions where surface-water supplies are limited and droughts intensify shortages. Some regions have addressed this challenge by transporting surface water to depleted aquifers, including California’s Central Valley and the Colorado River Basin in the United States, and the South–North Water Transfer system in the North China Plain. Existing irrigation and conveyance infrastructure, combined with favorable geological settings, can facilitate infiltration and aquifer recharge.
Together, these developments suggest a shift in perspective: aquifers should be understood as both a water resource and potential storage infrastructure. Where storage capacity, water supply, conveyance, and geology permit, managed aquifer recharge may reduce evaporative losses and strengthen water security during drought. This potential warrants attention in water planning, but its value must be assessed for each aquifer and recharge source.
