Geological Society of America

T5 In Honor of John M. (Jack) Sharp Jr.: Celebrating over 40 Years of Science, Students, and Stewardship I

Sunday, 22 October 2017
8:00 AM - 12:00 PM
Room 615/616/617

INVESTIGATING MORPHOLOGICAL CONTROLS ON HYPORHEIC EXCHANGE IN A MEANDERING RIVER

Paper number: T5-11
Program: Technical Sessions
Time: 10:40 AM – 10:55 AM

Authors

Neeraja Setlur Presenting Author
University of Texas at Austin, Austin, TX
Peter E. Carlson
University of Texas at Austin, Austin, TX
Stephen B. Ferencz
University of Texas at Austin, Austin, TX
Robert Roback
Los Alamos National Laboratory, Los Alamos, NM
George Perkins
Los Alamos National Laboratory, Los Alamos, NM
Jesus D. Gomez-Velez
New Mexico Institute of Mining and Technology, Socorro, NM
Bianca Valdez
University of Texas at Austin, Austin, TX
Amy De Luna
University of Texas at Austin, Austin, TX
Roger Craycroft
University of Texas at Austin, Austin, TX
Hayden Houpt
University of Texas at Austin, Austin, TX
Daniella Rempe
University of Texas at Austin, Austin, TX
Meinhard Cardenas
10220 Broomflower Dr, Austin, TX
Michael T. O'Connor
University of Texas at Austin, Austin, TX
Matthew H. Kaufman
University of Texas at Austin, Austin, TX

Abstract

The hyporheic zone (HZ) is critical to the biogeochemical and ecological processes of river corridors. The HZ is an active ecotone between surface water and groundwater (Boulton et al. 1998). In rivers that meander within an alluvial floodplain, exchange between groundwater and surface water is common, leading to the development of a HZ. Many factors control HZ hydraulics and chemistry. This study is an investigation on how channel morphology, meandering, and deposition influence hyporheic exchange along a reach of the east fork of the Jemez River in the Valles Caldera, New Mexico.

Using electrical resistivity data and auger/borehole cores, we intensively mapped the subsurface lithological composition of the site and identified flowpaths controlled by the deposition and burial of high hydraulic conductivity layers. The water table and groundwater flowpaths were mapped across the floodplain using a dense network of piezometers. Geochemical sampling and mapping for major cations, anions, and field parameters were used to supplement and support groundwater flow observations. Using water table monitoring, we found that an abandoned channel next to the streambed is hydraulically connected to the groundwater. The suite of observations collectively shows that deposition in a meandering fluvial environment influences the spatial patterns and properties of hyporheic exchange. This insight can be applied to issues pertaining to the transport of biogeochemically-important solutes through the river corridor. Further studies involving a more sophisticated and detailed modeling technique, a more extensive chemical analysis of the site, and comparison of this site to other similar settings are necessary in completing the understanding of the morphological controls of the hyporheic zone.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-308448

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