Abstract
Understanding the interactions of vegetation and soil water under varying hydrological conditions is crucial to aid quantitative assessment of land-use sustainability for maintaining water supply for humans and plants. Isolating and estimating the volume and ages of water stored within different compartments of the critical zone, and the associated fluxes of evaporation, transpiration, and groundwater recharge, facilitates quantification of these soil–plant-water interactions and the response of ecohydrological fluxes to wet and dry periods. We used the tracer-aided ecohydrological model EcH2O-iso to examine the response of water ages of soil water storage, groundwater recharge, evaporation, and root-uptake at a mixed land use site, in northeastern Germany during the drought of 2018 and in the following winter months. The approach applied uses a dynamic vegetation routine which constrains water use by ecological mechanisms. Two sites with regionally typical land-use types were investigated: a forested site with sandy soils and a deep rooting zone and a grassland site, with loamier soils and shallower rooting zone. This results in much younger water ages (<1 year) through the soil profile in the forest compared to the grass, coupled with younger groundwater recharge. The higher water use in the forest resulted in a more pronounced annual cycle of water ages compared to the more consistent water age in the loamier soil of the grasslands. The deeper rooting zone of the forested site also resulted in older root-uptake water usage relative to soil evaporation, while the grassland site root-uptake was similar to that of soil evaporation. Besides more dynamic water ages in the forest, replenishment of younger soil waters to soil storage was within 6 months following the drought (cf. >8 months in the grassland). The temporal evaluation of the responsiveness of soil and vegetation interactions in hydrologic extremes such as 2018 is essential to understand changes in hydrological processes and the resilience of the landscape to the longer and more severe summer droughts predicted under future climate change.
| Original language | English |
|---|---|
| Pages (from-to) | 3406-3425 |
| Number of pages | 20 |
| Journal | Hydrological Processes |
| Volume | 34 |
| Issue number | 16 |
| Early online date | 19 Jun 2020 |
| DOIs | |
| Publication status | Published - 30 Jul 2020 |
Bibliographical note
ACKNOWLEDGMENTSThe authors would like to acknowledge the European Research Council for funding the research (project GA 335910 VeWa). The authors would also like to acknowledge David Dubbert for the isotope analysis. Lastly, the authors thank the University of Aberdeen for the use of the High‐Performance Cluster (HPC), which was used for all model runs. The authors thank the issue editor (Paulo Benettin), Stefanie Lutz and two anonymous reviewers for their constructive comments through the review process which has aided in improving the manuscript.
Keywords
- Ecohydrological modelling
- forest hydrology
- isotopes
- tracer-aided modelling
- transit times
- water ages
Access to Document
- Smith_Isotope-aidedModelling_VOR
© 2020 The Authors. Hydrological Processes published by John Wiley & Sons Ltd. 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. https://creativecommons.org/licenses/by/4.0/