ALPAKAS: Alpine hydrographs and catchment attributes for karst springs

Abstract. Approximately 40 % of the European Alps consist of karstifiable rock. Due to their distinct recharge, storage, and discharge properties, karst aquifers are key components of the hydrological cycle and water supply in the Alpine region. However, large-sample datasets enabling comparative and data-driven analyses of karst spring discharge are currently lacking. Here, we present ALPAKAS (ALPine hydrographs and catchment Attributes for KArst Springs), the first large-sample benchmark dataset specifically dedicated to karst springs. ALPAKAS comprises 242 daily and 183 hourly quality-controlled and consistently preprocessed discharge time series from karst spring stations distributed across the EU Strategy for the Alpine Region (EUSALP) area, with stations located in seven countries. The dataset is complemented by both existing catchment delineations and circular catchment approximations, catchment-aggregated meteorological time series at multiple spatial scales, and a comprehensive set of static catchment attributes describing topography, positioning, meteorology, land cover, soil properties, and hydrogeology. In addition, the dataset includes karst-specific indices directly derived from the karst spring hydrographs.

ALPAKAS is available via Zenodo at https://doi.org/10.5281/zenodo.19329694 (Joger et al., 2026) under an open-access licence and is accompanied by comprehensive documentation. By providing a harmonized, large-sample compilation of karst spring catchments across diverse Alpine settings, the dataset enables comparative analyses, model benchmarking, and robust assessments of hydrogeological processes and climate change impacts.