Ellen K. Herman

Assistant Professor

Department of Geology, Bucknell University

Research

Disclaimer—I assume you are familiar with basic karst terminology if you are reading this page.  If you need some vocabulary help, try here.

I am very interested in the role of water-carried sediment in karst aquifers and landscapes.  During my graduate studies, I concentrated on understanding sediment that surfaced at springs, the downstream end of the average fluviokarst system.  While I am still working on the problem of what controls sediment flux out of karst springs, my interest in karst-carried sediment has expanded to include the influence of sediment load on the karst system itself.

In fluviokarst, surface fluvial processes interact with karst processes to produce a unique setting for water flow.  Because fluviokarst systems often have active underground streams and water-filled conduits, their flow is not governed by Darcy’s law and can carry substantial sediment loads in the subsurface.  That’s why springs sometimes look like they are discharging chocolate milk rather than crystal clear water.  As the subsurface conduits and fissures of the aquifer carry sediment and control the flux we see at a spring, the sediment should also affect the conduits and fissures, enlarging them by abrasion and erosion.  We see these processes in surface streams in bedrock all the time.  Streams in the subsurface, running over soft dissolvable rock, should experience similar processes.  Understanding these processes is at the center of my current research—in the lab, in the field, and ultimately in computer model form.

GSA 2009 National Meeting Abstract on this topic

Amy Jewett, Bucknell ‘11, at Smullton Sinks in Centre County, PA, collects bedload sediment for our work

Flood upstream of Tytoona Cave, Blair County, PA

 

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