Abstract
Stable isotopes of water are ideal tracers to integrate into process-based models, advancing ecohydrological understanding. Current tracer-aided ecohydrological modeling is mostly conducted in relatively small-scale catchments, due to limited tracer data availability and often highly damped stream isotope signals in larger catchments (>100 km2). Recent model developments have prioritized better spatial representation, offering new potential for advancing upscaling in tracer-aided modeling. Here, we adapted the fully distributed EcH2O-iso model to the Selke catchment (456 km2, Germany), incorporating monthly sampled isotopes from seven sites between 2012 and 2017. Parameter sensitivity analysis indicated that the information content of isotope data was generally complementary to discharge and more sensitive to runoff partitioning, soil water and energy dynamics. Multi-criteria calibrations revealed that inclusion of isotopes could significantly improve discharge performance during validations and isotope simulations, resulting in more reasonable estimates of the seasonality of stream water ages. However, capturing isotopic signals of highly non-linear near-surface processes remained challenging for the upscaled model, but still allowed for plausible simulation of water ages reflecting non-stationarity in transport and mixing. The detailed modeling also helped unravel spatio-temporally varying patterns of water storage-flux-age interactions and their interplay under severe drought conditions. Embracing the upscaling challenges, this study demonstrated that even coarsely sampled isotope data can be of value in aiding ecohydrological modeling and consequent process representation in larger catchments. The derived innovative insights into ecohydrological functioning at scales commensurate with management decision making, are of particular importance for guiding science-based measures for tackling environmental changes.
| Original language | English |
|---|---|
| Article number | e2022WR033033 |
| Journal | Water Resources Research |
| Volume | 59 |
| Issue number | 3 |
| Early online date | 21 Feb 2023 |
| DOIs | |
| Publication status | Published - Mar 2023 |
Bibliographical note
Funding Information:This work was supported by the Modular Observation Solutions for Earth Systems—MOSES project and the Terrestrial Environmental Observatories—TERENO project. Funding was also received for Doerthe Tetzlaff through the Einstein Research Unit “Climate and Water under Change” from the Einstein Foundation Berlin and Berlin University Alliance. Contributions by Chris Soulsby were supported by the Leverhulme Trust through the ISO‐LAND project (RPG 2018 375). The authors thank Michael Rode and Ralf Merz for permitting the use of the water stable isotope data and for constructive discussions related to the data analysis. The authors would like to thank Marco Maneta and Aaron Smith for their support and discussion on the modeling. The authors thank the Editor Peter Troch, the Associate Editor and three anonymous reviewers for their constructive comments. The authors also thank the German Weather Service, the Federal Institute for Geosciences and Natural Resources and the State Agency for Flood Protection and Water Management Saxony‐Anhalt for the model setup data. Open Access funding enabled and organized by Projekt DEAL.
Publisher Copyright:
© 2023. The Authors.
Keywords
- green-blue water partitioning
- isotope-aided ecohydrological modeling
- spatial heterogeneity of catchment functioning
- stable water isotope monitoring in large-scale catchments
- upscaling to larger catchment
- water storage-flux-age interactions
Access to Document
- Yang_etal_WRR_Upscaling_Tracer‐Aided_Ecohydrological_VOR
© 2023. The Authors.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited