22-9 Assessing Groundwater Contributions to Surface Water Chemistry in Tatnuck Brook Using Thermal and Chemical Indicators

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

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Spatial patterns in surface water quality reflect the combined interactions of hydrologic, physical, and biological processes operating within a watershed. Groundwater-surface water exchange is often hypothesized to play a key role in regulating temperature, nutrient availability and dissolved oxygen, yet its relative importance is frequently difficult to resolve. This study examines water quality dynamics within the Tatnuck Brook watershed in Central Massachusetts, to evaluate whether groundwater inputs exert a detectable influence on surface water chemistry and thermal patterns.

Bi-weekly field monitoring was conducted across Patch Reservoir and downstream using multi-parameter sensor probes to measure temperature, conductivity, and dissolved oxygen. Thermal infrared imaging was employed to identify surface temperature anomalies potentially associated with groundwater inflow. Water samples were analyzed for total phosphorus, nitrates, nitrites, and total dissolved solids to characterize chemical gradients across the system. Spatial and statistical analyses were used to assess whether observed water quality patterns were consistent with groundwater discharge signals.

Results indicate no direct thermal or chemical evidence of groundwater discharge within the study area. Instead, dissolved oxygen exhibited strong spatial structure, with elevated concentrations near the outlet and a decline with increasing distance downstream. This pattern suggests that surface water processes such as outlet-driven mixing, aeration, flow velocity, and biological activity dominate oxygen dynamics in the system, potentially masking or overwhelming subtler groundwater signals.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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