Testing a spatially distributed tracer‐aided runoff model in a snow‐influenced catchment: Effects of multicriteria calibration on streamwater ages |
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Authors: | Thea I. Piovano Doerthe Tetzlaff Pertti Ala‐aho Jim Buttle Carl P. J. Mitchell Chris Soulsby |
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Affiliation: | 1. Northern Rivers Institute, University of Aberdeen, Aberdeen, UK;2. Ecohydrology IGB Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany;3. Department of Geography, Humboldt University Berlin, Berlin, Germany;4. Water Resources and Environmental Engineering Research Unit, Faculty of Technology, University of Oulu, Finland;5. Department of Geography, Trent University, Peterborough, Ontario, Canada;6. Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada |
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Abstract: | Integrating stable isotope tracers into rainfall‐runoff models allows investigation of water partitioning and direct estimation of travel times and water ages. Tracer data have valuable information content that can be used to constrain models and, in integration with hydrometric observations, test the conceptualization of catchment processes in model structure and parameterization. There is great potential in using tracer‐aided modelling in snow‐influenced catchments to improve understanding of these catchments' dynamics and sensitivity to environmental change. We used the spatially distributed tracer‐aided rainfall‐runoff (STARR) model to simulate the interactions between water storage, flux, and isotope dynamics in a snow‐influenced, long‐term monitored catchment in Ontario, Canada. Multiple realizations of the model were achieved using a combination of single and multiple objectives as calibration targets. Although good simulations of hydrometric targets such as discharge and snow water equivalent could be achieved by local calibration alone, adequate capture of the stream isotope dynamics was predicated on the inclusion of isotope data in the calibration. Parameter sensitivity was highest, and most local, for single calibration targets. With multiple calibration targets, key sensitive parameters were still identifiable in snow and runoff generation routines. Water ages derived from flux tracking subroutines in the model indicated a catchment where runoff is dominated by younger waters, particularly during spring snowmelt. However, resulting water ages were most sensitive to the partitioning of runoff sources from soil and groundwater sources, which was most realistically achieved when isotopes were included in the calibration. Given the paucity of studies where hydrological models explicitly incorporate tracers in snow‐influenced regions, this study using STARR is an important contribution to satisfactorily simulating snowpack dynamics and runoff generation processes, while simultaneously capturing stable isotope variability in snow‐influenced catchments. |
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Keywords: | multicriteria calibration snow‐influenced catchments stable isotopes STARR (spatially distributed tracer‐aided rainfall‐runoff) streamwater ages tracer‐aided model |
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