Spatial identification of vulnerable regions for combined flood and drought prevention in Southern Germany

The increasing frequency of hydro-meteorological extremes in Germany has resulted in significant economic and environmental losses, totaling at least EUR 145 billion in damages between 2000 and 2021. While these events affect the nation at large, the vulnerability of Germany’s administrative districts varies drastically due to local differences in topography, weather patterns, and land-use characteristics. Adaptation to climate risks requires both risk identification and the strategic placement of Decentralised Water Retention Measures (DWRM) capable of buffering both excess and scarcity. We present a Multi-Criteria Decision Analysis (MCDA) framework that ranks the districts in Southern Germany (Baden-Württemberg and Bavaria) based on their climate vulnerability. The proposed framework synthesizes diverse hydro-meteorological indicators into a single index, allowing for an objective comparison of regional risks. This study utilizes the comprehensive dataset provided by the Climate Service Center Germany (GERICS), consisting of 85 regional climate model simulations, evaluating future hydro-meteorological trajectories under three different Shared Socioeconomic Pathway (SSP) emission scenarios and combines an Entropy Weight Method to objectively determine the importance of each indicator by calculating its information utility based on data variance across the study area. Thereafter, the vulnerability of each district was calculated based on the geometric distance to theoretical ideal solutions using the TOPSIS method. The results of this analysis aim to identify persistent hotspots that consistently rank as highly vulnerable across all climate trajectories and emission scenarios. These identified districts will be spatially mapped and linked to their respective hydrological catchments to facilitate future high-resolution hydrological modelling and site-specific engineering assessments.

Using the screening outputs, three representative case study areas are selected in which the water balance will be modelled in detail. Building on this, the aim is to develop a coupled simulation tool, based on SWAT+, that identifies potential decentralized retention areas and evaluates their effectiveness as a combined measure for drought and flood prevention. Once development is complete, the tool will be made publicly available to enable broad application in water resource management and promote knowledge transfer between research and practice. Future results will be disseminated through policy briefs, scientific publications, and participatory workshops to engaged decision-makers and stakeholders from administration and planning at an early stage in the development of sustainable water strategies.