2 Advances in characterizing groundwater, surface water, and their interactions

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.

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 25

Precipitation Regimes Shape Dynamic Till–Bedrock Connectivity and Flow Patterns in Temperate Forested Headwater Catchments

Paper number: 2-9
Program: Technical Sessions
Time: 10:40 AM – 11:00 AM

Authors

Abstract

Climate-driven changes in precipitation regimes are altering hydrologic processes in temperate forested headwater catchments, with important implications for streamflow generation. In the northeastern United States, increases in the magnitude and frequency of extreme precipitation events have intensified hydrologic connectivity. However, how these changes influence coupling between shallow glacial till and underlying fractured bedrock aquifers remains poorly constrained. Till–bedrock connectivity plays a critical role in regulating runoff sources, response times, and the partitioning of water between shallow and deep flow paths. 

Building on prior analysis of long-term discharge and meteorological records from the Harvard Forest, we integrate groundwater-level monitoring and stable water isotope sampling across multiple headwater catchments in north-central Massachusetts. These datasets provide insight into flow path activation and till–bedrock connectivity under evolving climate conditions. We further compare catchments spanning three levels of wetland connectivity to assess how wetlands influence atmospheric coupling and subsurface flow dynamics. 

Our results suggest that extreme precipitation events preferentially activate shallow flow paths in non-wetland catchments, producing faster quick flow generation. Analysis of groundwater level and discharge indicate limited contribution of deeper (> 3m) fractured bedrock storage to streamflow. In contrast, wetland-sourced catchments exhibit an atmospherically coupled signature, but exhibit muted quick flow generation changes, suggesting that wetlands promote shallow, well-mixed storage and buffer against rapid, climate-driven hydrologic change. These findings highlight how climate influences till–bedrock connectivity and flow generation patterns across forested headwater catchments. 

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

doi: 10.1130/abs/2026NE-411255

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