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Title: Interflow dynamics on a low relief forested hillslope: Lots of fill, little spill

In this paper, we evaluated the occurrence of perching and interflow over and within a sandy clay loam argillic horizon within first-order, low-relief, forested catchments at the Savannah River Site (SRS) in the Upper Coastal Plain of South Carolina. We measured soil hydraulic properties, depths to the argillic layer, soil moisture, shallow groundwater behavior, interflow interception trench flows, and streamflow over a 4-year period to explore the nature and variability of soil hydraulic characteristics, the argillic “topography”, and their influence on interflow generation. Perching occurred frequently within and above the restricting argillic horizons during our monitoring period, but interflow was infrequent due to microtopographic relief and associated depression storage on the argillic layer surface. High percolation rates through the argillic horizon, particularly through soil anomalies, also reduced the importance of interflow. Interflow generation was highly variable across eleven segments of a 121 m interception trench. Hillslopes were largely disconnected from stream behavior during storms. Hillslope processes were consistent with the fill-and-spill hypothesis and featured a sequence of distinct thresholds: vertical wetting front propagation to the argillic layer; saturation of the argillic followed by local perching; filling of argillic layer depressions; and finally connectivity of depressions leading to interflow generation. Lastly,more » analysis of trench flow data indicated a cumulative rainfall threshold of 60 mm to generate interflow, a value at the high end of the range of thresholds reported elsewhere.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [2] ;  [2]
  1. Univ. of Georgia, Athens, GA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Univ. of Georgia, Athens, GA (United States)
  3. Univ. of Saskatchewan, Saskatoon, SK (Canada); Luxembourg Institute of Science and Technology, Esch-sur-Alzette (Luxembourg)
  4. Univ. of Saskatchewan, Saskatoon, SK (Canada); Univ. of Aberdeen, Aberdeen (United Kingdom)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Institute and Environmental Sciences Division
Publication Date:
OSTI Identifier:
1247925
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Hydrology
Additional Journal Information:
Journal Volume: 534; Journal Issue: C; Journal ID: ISSN 0022-1694
Publisher:
Elsevier
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES Interflow; Argillic layer; Low relief; Fill-and-spill