Process-based hydrological modeling by integrating pedology, geophysics and soil hydrology

• Applicant: Edoardo Martini, Ph.D.
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management ; Soil Sciences
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397711989

• Final Report Year: 2023

Final Report Abstract

The primary objective of the project was to develop and test an integrated approach consisting of process-based soil hydrological modeling for quantifying the vadose zone water fluxes for a typical hillslope, combining pedology-oriented local measurements of soil water content and subsurface characterization from time-lapse multi-configuration electro-magnetic induction (EMI) measurements. A soil monitoring network (STH-net) was implemented at the Schäfertal hillslope site (Central Germany). It consist of 8 soil profiles described, sampled and instrumented with time-domain reflectometry (TDR) probes installed at multiple depths within the unsaturated zone, soil temperature probes and monitoring wells, and comprises a weather station. Since January 2019, the STH-net delivers data with a 10-min interval, freely available. Repeated electro-magnetic induction (EMI) measurements were conducted at the site using the multi-configuration device CMD-MiniExplorer (GF Instruments, Brno, Czech Republic) to characterize the subsurface architecture and properties of the study area. The measured data were processed via geophysical inversion using different codes. The results show that the method is capable of identifying the major soil units and soil horizons on a qualitative level. Limitations exist in the quantitative use of the data, as the inversion results do not match the observed electrical conductivity values measured in situ with TDR probes. The observed soil water content dynamics were used in a data assimilation routine to estimate the effective material properties of the instrumented soil profiles. The soil hydraulic parameters were found to vary significantly within nearby monitoring stations due to local heterogeneity. A physically-based, 3-D numerical model was implemented for the study area to simulate the soil water fluxes and explore the level of model complexity required for characterizing the hydrological processes, with special focus on the subsurface properties (i.e., soil horizons, heterogeneity and subsurface parameterization). On the one hand, the results show that increasing the complexity of the subsurface representation improve the modeling results at the pedon scale, as simulations using a subsurface characterization that accounts for soil layering and distinct material properties outperformed those using a simplified representation of the subsurface. On the other hand, the correct parameterization of the upper model boundary, specifically the vegetation dynamics and the evapotranspiration appeared to be critical for the correct simulation of the water dynamics in the vadose zone. Future work on linking detailed but local subsurface characterization to hydrological processes at larger scales must account for more advanced numerical tools and possibly make use of multiple near-surface geophysical measurement techniques and site inter-comparison towards a generalized understanding of the subsurface control on the infiltration processes. At the same time, the upper and lower model boundaries need to be modeled with the focus on their spatial heterogeneity and temporal dynamics, as they can play a major role in controlling the hydrological processes, especially when looking at spatial scales beyond the pedon. Such approach require joint efforts and the synergic combination of experimental and numerical expertises.

Publications

• How can we model subsurface stormflow at the catchment scale if we cannot measure it?. Hydrological Processes, 33(9), 1378-1385.
  Chifflard, Peter; Blume, Theresa; Maerker, Katja; Hopp, Luisa; van Meerveld, Ilja; Graef, Thomas; Gronz, Oliver; Hartmann, Andreas; Kohl, Bernhard; Martini, Edoardo; Reinhardt‐Imjela, Christian; Reiss, Martin; Rinderer, Michael & Achleitner, Stefan
  
• Process-based hydrological modeling by integrating pedology, geophysics and soil hydrology. Geophysical Research Abstracts - Vol. 21, EGU2019-3960, EGU General Assembly, 7-13 April 2019 - Vienna, Austria, 2019.
  Martini, Edoardo; Wollschläger, Ute; Bittelli, Marco; Tomei, Fausto; Werban, Ulrike; Zacharias, Steffen & Roth, Kurt
  
• Process-based hydrological modeling: accounting for subsurface heterogeneity by integrating pedology, geophysics and soil hydrology. (2020, 3, 23). American Geophysical Union (AGU).
  Martini, Edoardo; Wollschläger, Ute; Bittelli, Marco; Tomei, Fausto; Werban, Ulrike; Zacharias, Steffen & Roth, Kurt
  
• Dataset, STH-net, EUDAT-B2SHARE
  Martini, E.; Kögler, S.; Kreck, M.; Werban, U.; Wollschläger, U. & Zacharias, S.
  
• Hillslope-scale mapping and numerical representation of the subsurface heterogeneity towards an improved process-based hydrological modelling. (2021, 3, 3). American Geophysical Union (AGU).
  Martini, Edoardo; Wollschläger, Ute; Bittelli, Marco; Tomei, Fausto; Werban, Ulrike; Zacharias, Steffen & Roth, Kurt
  
• STH-net: a soil monitoring network for process-based hydrological modelling from the pedon to the hillslope scale. Earth System Science Data, 13(6), 2529-2539.
  Martini, Edoardo; Bauckholt, Matteo; Kögler, Simon; Kreck, Manuel; Roth, Kurt; Werban, Ulrike; Wollschläger, Ute & Zacharias, Steffen
  
• STH-net: a soil monitoring network for process-based hydrological modelling from the pedon to the hillslope scale. First OZCAR-TERENO International Conference. Strasbourg, France & online, 5-7 October 2021.
  Martini, Edoardo; Bauckholt, Matteo; Kögler, Simon; Kreck, Manuel; Roth, Kurt; Werban, Ulrike; Wollschläger, Ute & Zacharias, Steffen