<p class="MDPI12titleori1" style="mso-line-height-alt: 14.0pt;"><span lang="EN-US" style="mso-bidi-font-size: 18.0pt; mso-ligatures: standardcontextual;">Hydrodynamic Parameter Estimation for Simulating Soil-Vegetation-Atmosphere Hydrology Across Forest Stands in the Strengbach Catchment

Modeling the water cycle requires a proper understanding of interactions within the critical zone compartments - soil, vegetation, and atmosphere. Among the key processes involved, soil water flow modeling using a mechanistic approach relies on accurately determining the hydrodynamic parameters that define the soil hydraulic conductivity and water retention curves. Various estimation methods exist, including pedotransfer functions (PTFs) based on soil properties derived from field samples, and inverse modeling approaches that adjust hydrodynamic parameters to minimize discrepancies between simulations and observations. While the PTF approach is widely used due to its simplicity and limited technical requirements, inverse modeling demands specific instrumentation and advanced numerical tools. This study, conducted on the experimental site of the Hydro-Geochemical Environmental Observatory - the Strengbach forested catchment - aimed to determine the optimal hydrodynamic parameters for two contrasting forest plots, one dominated by spruce and the other by beech. The results highlight the importance of accounting for soil stoniness to improve the efficiency of flow modelling, as well as the need to assess the robustness of the derived parameter set, given that selecting an optimal calibration period remains challenging and that the model should be able to represent hydrological variability.