22 Advances in characterizing groundwater, surface water, and their interactions (Posters)

This session focuses on characterizing groundwater, surface water, and their interactions through fieldwork, modeling, and data synthesis. We welcome submissions addressing flow, transport, water quality, and water levels under both typical and extreme conditions.

Monday, 23 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Spatial Assessment of Sea-Level Rise and Flooding Risks to Onsite Wastewater Treatment Systems in Charlestown, Rhode Island

Paper number: 22-12
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Coastal communities that rely on onsite wastewater treatment systems (OWTS) are increasingly exposed to the impacts of sea-level rise (SLR) and associated coastal flooding. This GIS-based analysis assesses the present and future exposure of OWTS to coastal flooding in Charlestown, Rhode Island, a low-lying town on the Atlantic Coast, where all residences rely on decentralized wastewater systems. High-resolution (1-m) LiDAR-derived elevation data were integrated with STORMTOOLS Design Elevation (SDE) flood rasters representing 100-year storm events under three SLR scenarios (0.5, 1.0, and 1.5 m above current mean sea level). Flood depths were extracted at each OWTS location and categorized into hazard classes using established coastal flooding thresholds. Under a moderate SLR scenario of 1.0 m, more than 40% of systems shift from minor or moderate exposure into major or extreme hazard categories, with impacts intensifying under higher scenarios and affecting over 75% of systems at 1.5 m. Overall, the study highlights the utility of GIS-based flood hazard mapping as a screening-level approach for identifying at-risk wastewater infrastructure. These findings provide a spatial framework for future integrated assessments of groundwater and nutrient dynamics. As a transferable framework, the approach is broadly applicable to low-lying coastal communities reliant on decentralized wastewater, particularly in settings with shallow groundwater and complex geomorphology.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411322

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