146-1 Sea-level Induced Groundwater Rise and Shifting Flow Patterns at a Polluted Coastal Site.

Session: Contaminants Near Groundwater-Surface Water Interfaces (Posters)

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Abstract:

As sea-level rises, coastal groundwater systems respond with a combination of rising water tables, increases in discharge to drainages, and/or a rearrangement of the groundwater flow. Such groundwater responses to sea-level rise are still difficult to forecast and control, as many coastal adaptation plans focus primarily on surficial flooding hazards. At polluted coastal sites, the role of groundwater responses to sea-level rise on cleanup activities and long-term planning may be even more important. For example, the solubility and mobility of contaminants are dependent on the redox conditions, which are in part set by water table position and changing porewater salinities with saline groundwater intrusion. Furthermore, increasing water content from rising water tables leads to higher hydraulic conductivities that can also increase mobility of soil contaminants. We developed and applied a groundwater flow model of the Zeneca site in Richmond, California to test how sea-level rise may control pollution-related groundwater responses. We analyzed how sea level scenarios shifted particle flow paths, discharge locations, and specifically flow pathways near remediation activities. We found that groundwater flow pathways are sensitive to sea-level rise and that these changes may require shifts in remediation activities if the pollutants persist long into the future. We expect that these changes to groundwater levels and flow paths at the Zeneca site are relevant to long-term management and planning at other coastal remediation sites to help make resilient and adaptable remediation plans that quantitatively address spatiotemporal groundwater responses to sea-level rise.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6235

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