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Consistent modelling of transport processes and travel times - coupling soil hydrologic processes with StorAge Selection functions
  • Robin Schwemmle,
  • Markus Weiler
Robin Schwemmle
Albert-Ludwigs-University Freiburg

Corresponding Author:robin.schwemmle@hydrology.uni-freiburg.de

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Markus Weiler
University of Freiburg, Germany
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Understanding the transport processes and travel times of pollutants in the subsurface is crucial for an effective management of drinking water resources. Transport processes and soil hydrologic processes are inherently linked to each other. In order to account for this link, we couple the process-based hydrologic model RoGeR with StorAge Selection (SAS) functions. We assign to each hydrological process a specific SAS function (e.g. power law distribution function). To represent different transport mechanisms, we combined a specific set of SAS functions into four transport model structures: complete-mixing, piston flow, advection-dispersion and advection-dispersion with time-variant parameters. In this study, we conduct modelling experiments at the Rietholzbach lysimeter, Switzerland. All modelling experiments are benchmarked with HYDRUS-1D. We compare our simulations to the measured hydrologic variables (percolation and evapotranspiration fluxes and soil water dynamics) and the measured water stable isotope signal (18O) in the lysimeter seepage for a period of ten years (1997-2007). An additional virtual bromide tracer experiment was used to benchmark the models. Additionally, we carried out a sensitivity analysis and provide Sobol indices for soil hydrologic model parameters and SAS parameters. Our results show that the advection-dispersion transport model produces the best results. And thus, advective-dispersive transport processes play a dominant role at Rietholzbach lysimeter. Our modelling approach provides the capability to test hypotheses of different transport mechanisms and to improve process understanding and predictions of transport processes. Overall, the combined model allows a very effective simulation of combined flux and transport processes at various temporal and spatial scales.
25 Feb 2023Submitted to ESS Open Archive
27 Feb 2023Published in ESS Open Archive