Drought analysis in Southern Germany using ecosystem-inspired resilience measures

Soil moisture is an essential variable for drought analysis in hydrology because it reflects weather variability, antecedent conditions, and available water storage in a joint manner, and it is strongly affected by local site characteristics such as soil texture and land use. While standard metrics used to describe hydrological drought (e.g., magnitude, intensity, severity, duration) are useful for anticipating potential impacts of drought on dependent processes (e.g., agricultural failure, groundwater and streamflow recharge), they only partially describe the response of the soil moisture system itself. In this study, we aim to analyse soil moisture and drought variability inspired by a resilience quantification approach from ecosystem science, which jointly considers disturbance impact (e.g., magnitude and intensity) and recovery rate. For the pilot studies in Southern Germany, we used long-term soil moisture data (2000 to 2020) at high spatiotemporal resolution (daily, 2 km) generated by an advanced atmospheric-hydrological modelling system, WRF-Hydro, driven by reanalysis data (ERA5). In contrast to observational products, modelled data allow us to analyse soil moisture variability across different soil depths. Suitable resilience indicators are selected and applied to daily soil water storage to examine how drought responses vary with depth. Preliminary results indicate a strong influence of soil depth on soil moisture dynamics, with particularly pronounced drought events and low recovery rates in the deepest soil layer. The next step is to quantify the recovery rate of droughts across different site characteristics (e.g., land use, soil type) within the entire study domain. This study contributes to the development of a resilience assessment framework for hydrology to support monitoring, early warning, and risk assessment of droughts.