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Channeling in Fractured Bedrock

Active Dates: Current

Participants: Participants: Matt Becker and Renee Bourque (UB Geology); George Tsoflias (U. Kansas)

Support: National Science Foundation, Department of Energy

Water flows through bedrock fractures in a very uneven manner. Even in a single fracture, regions of moving water can be located adjacent to relatively stagnant water. This heterogeneous flow behavior complicates the prediction of solute transport, monitoring of pollution, and remediation of contaminated bedrock systems.

Site location, Altona, NYGPR scan of the Altona site

We study channeled flow behavior at a unique site in which the most of the overburden was stripped from the sandstone bedrock during the previous glacial retreat. We have access to saturated bedrock fractures that are only meters below surface. This allows us to image fractures and fluids using surface ground penetrating radar.

GPR Data from the Altona site

In previous studies we imaged saline tracer as it circulated between two wells in a single subhorizontal bedrock fracture. The tracer movement highlighted the highly heterogeneous nature of flow in bedrock fractures.

Our more recent work has focused on refining the imaging techniques by using both amplitude and phase returns. Contrary to the common expectation, we find that resolution of both saline concentratino and fracture aperture improve with decreasing frequency.