105 Coastal Hydrogeology in an Age of Rising Seas (Posters)

As sea levels rise, understanding hydrogeology is crucial in coastal areas. Seawater intrusion can lead to loss of potable or agricultural water supplies, and water table rise due to increasing sea level can lead to increased flooding and affect infrastructure.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Influence of cryogenic processes on hydrological processes and contaminant transport in the coastal critical zone

Paper number: 105-6
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

In cold regions, the amplified rate of climate change is altering seasonal cryogenic processes including the spatiotemporal distribution of seasonally frozen ground (SFG) and snow. The extent and duration of SFG and snow exert strong control over water and contaminant fluxes throughout the critical zone. These processes are important in the Canadian Maritimes where homeowners in small, rural communities rely on private wells and onsite wastewater (septic) systems during all seasons. Changes in seasonal vadose zone saturation are expected from altered cryogenic processes. For example, more frequent melt events during winter will likely influence pore-water residence time and microbial transport dynamics, ultimately threatening groundwater quality and receiving surface waters. To investigate these dynamics, we established a coastal groundwater observatory in a provincial park along the north shore of Nova Scotia, Canada. We installed cross-shore transects of soil moisture/temperature probes and piezometers from park outhouses to coastal wetlands and conducted repeated geophysical monitoring and groundwater sampling. Preliminary field investigations highlight a shallow water table during the melt season, which we expect to facilitate contaminant transport into groundwater. With field observations guiding two variably saturated hydrologic models, we investigate the impact of these changing cryogenic conditions on wastewater contaminant fate and transport during seasonal transitions and melt events. We adopt a paired modeling approach by combining the Simultaneous Heat and Water (SHAW) model, to simulate critical zone dynamics and the influence of snowmelt and ground freeze-thaw, with HYDRUS-2D to simulate deeper groundwater flow and contaminant transport. Once calibrated, the models will be forced with downscaled climate scenarios from NASA (NEX-GDDP-CMIP6). Results from this research will be used to evaluate if present design guidelines for onsite wastewater treatment systems can be modified to be more resilient in a changing climate. 

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

doi: 10.1130/abs/2025AM-413276

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