EGU25-12583, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-12583
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Effect of dynamic representation of root water uptake in a hydrological model on the classification of drought events
Sven Westermann1,2, Friedrich Boeing1, Carla Peter1, Julian Schlaak1, Andreas Marx1, Stephan Thober1, and Anke Hildebrandt1,2,3
Sven Westermann et al.
  • 1Helmholtz Centre for Environmental Research - UFZ, Computational Hydrosystems, Leipzig, Germany (sven.westermann@ufz.de)
  • 2Friedrich Schiller University Jena, Institute of Geosciences, Jena, Germany
  • 3German Centre for Integrative Biodiversity Research, Halle-Jena-Leipzig, Germany

With climate change, drought events are more likely to occur in Central Europe. The German Drought Monitor is an established tool in Germany for assessing the severity of soil moisture drought events. Based on soil moisture simulations with the mesoscale hydrological model (mHM), it categorizes the probability of occurrence of the current soil dryness compared to a historical reference period. In this model, the potential access to and uptake of soil water by the roots of the vegetation is static in time and determined by the root fraction in each soil layer. Field estimates of root water uptake suggest that this behavior is unrealistic and limits the impact of the vegetation on the evapotranspiration in the model. Therefore, we compared two schemes with and without root length density constraint, resulting in a more or less dynamic representation of root water uptake in the German Drought Monitor. We found that when root length density was removed, the model yielded a more dynamic uptake pattern, which was also comparable to observations. We investigate whether and which parameters and target variables (actual evapotranspiration, soil moisture, soil moisture index indicating drought) are sensitive to this adaptation.

How to cite: Westermann, S., Boeing, F., Peter, C., Schlaak, J., Marx, A., Thober, S., and Hildebrandt, A.: Effect of dynamic representation of root water uptake in a hydrological model on the classification of drought events, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12583, https://doi.org/10.5194/egusphere-egu25-12583, 2025.