H31K-04
Solute tracer transport does not vary systematically with stream discharge or geomorphology
Wednesday, 16 December 2015: 08:45
3018 (Moscone West)
Noah M Schmadel1, Adam S Ward1, Marie Juliette Kurz2, Jan H Fleckenstein2, Jay P Zarnetske3, David M Hannah4, Theresa Blume5, Michael Vieweg2, Phillip Blaen4, Christian Schmidt6, Julia Knapp7, Megan Klaar4, Paul Romeijn4, Thibault Datry8, Toralf Keller6, Silvia Folegot4, Amaia Irene Marruedo Arricibita9 and Stefan Krause4, (1)Indiana University Bloomington, School of Public and Environmental Affairs, Bloomington, IN, United States, (2)Helmholtz Centre for Environmental Research UFZ Leipzig, Leipzig, Germany, (3)Michigan State University, East Lansing, MI, United States, (4)University of Birmingham, Birmingham, United Kingdom, (5)GFZ German Research Centre, Potsdam, Germany, (6)Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany, (7)University of Tübingen, Tübingen, Germany, (8)IRSTEA Lyon, Villeurbanne Cedex, France, (9)Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
Abstract:
Improving predictive capabilities of solute transport through stream systems requires meaningful comparison of dominant transport controls across different discharge conditions and spatial scales. While in-stream tracer tests are commonly used to assess transport behavior at reach scales (e.g., transient storage and dispersion), a main challenge is to separate the controls from the timescale represented in the recovered tracer response that primarily varies with discharge and reach length. We repeated conservative solute tracer tests along a 1-km study reach during a storm event and its recession to generate a suite of timescales and test how discharge and reach length selection affect the interpretation of transport processes. We set out to examine how physical transport processes change with discharge, how individual segments within the continuous study reach respond differently to discharge, and determine whether combining segments into longer study reaches produces a different interpretation of processes. We found that the temporal metrics of the recovered in-stream tracer responses were mostly insensitive to changing discharge and most segments did not respond differently even though morphologic characteristics between segments were distinct. However, segment length selection did influence the interpretation of transport processes. These results suggest that advection was the primary control reflected in the observations, which muted process change with discharge and the influence of spatial heterogeneity. This study indicates that the influence of advection on the tracer timescale must be considered before such reach scale observations can be used to infer transport controls at larger network scales.
