Occurrence of Perched Saturation and Interflow Over an Argillic Horizon in a Low Relief Hillslope
Author(s)
Greco, James
Jackson, C. Rhett
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Abstract
Many of the soils in the southeastern
US are characterized by an argillic, or clay horizon, that
largely parallels the soil surface at depths ranging from a
few centimeters to 100 centimeters. The degree to which
these argillic horizons alter subsurface movement of infiltrated water is not well known. Interflow, or throughflow, is shallow lateral subsurface flow that moves over a
horizon that restricts percolation. This research investigates how often and under what conditions a relatively
deep (20-150+
cm) argillic horizon on low slope (2-6%)
hillsides causes interflow to occur. Research is being
conducted at the Savannah River Site, Aiken, South Carolina, on a small zero-order watershed. In the first phase of
this research, a high resolution topographic map of the
clay layer was developed. This map will be used to instrument designated “low” spots with max rise piezometers in order to determine if there is channelized subsurface flow. In situ conductivities of the clay layer and the
surface horizons were measured using an Amoozegar meter, and bulk density samples were taken and measured.
Along with soil topographic measurements, data-logging
piezometers have been installed to measure the piezometric head above, in, and below the argillic horizon to further investigate interflow as a potential hydraulic routing
mechanism. The stream that drains the catchment was
instrumented with a 2’ H flume and data-logging pressure
transducer to measure stream flow. Climate data including precipitation, barometric pressure and temperature, are
being continuously collected in an open area approximately ¼ mile from the study site. Combining the shallow surface and subsurface piezometric heads with stream
flow rates, we should be able to determine if and when the
clay layer is contributing to interflow.
Sponsor
Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of Technology
Date
2007-03
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