Ice sheet dynamics drive pronounced changes in the subsurface freshwater-saltwater interface

Geophysical Research Letters
By: , and 

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Abstract

Saltwater is migrating into freshwater aquifers globally with water quality and biogeochemical implications, yet saltwater intrusion in glaciated regions is sparsely investigated. Field observations suggest that groundwater head in glaciated systems is influenced by ice sheet forcings and provides evidence that seawater infiltrated into offshore aquifers during past deglaciation events. To understand links between ice sheet dynamics, groundwater head, and saltwater intrusion, we use numerical models to explore the effects of deglaciation on nearshore head and salinity distributions. We find that ice sheet thinning diminishes groundwater head, and the resulting shift in subsurface pressure gradients drives rapid landward movement of the subsurface freshwater-saltwater interface up to 4.0 km or 1.3 m per m ice sheet loss. Results highlight an overlooked saltwater intrusion mechanism that aligns with field observations and affects glaciated coastlines undergoing ice sheet retreat, underscoring the need to consider this mechanism in studies of contemporary coastal water quality.

Suggested Citation

Guimond, J., Mohammed, A., Kurylyk, B.L., Walvoord, M.A., and Bense, V.F., 2026, Ice sheet dynamics drive pronounced changes in the subsurface freshwater-saltwater interface: Geophysical Research Letters, v. 53, no. 6, e2025GL120376, 10 p., https://doi.org/10.1029/2025GL120376.

Publication type Article
Publication Subtype Journal Article
Title Ice sheet dynamics drive pronounced changes in the subsurface freshwater-saltwater interface
Series title Geophysical Research Letters
DOI 10.1029/2025GL120376
Volume 53
Issue 6
Publication Date March 16, 2026
Year Published 2026
Language English
Publisher American Geophysical Union
Contributing office(s) WMA - Earth System Processes Division
Description e2025GL120376, 10 p.
Additional publication details