Geomorphological and hydrological controls on shallow karst depressions (dayas) on a planar carbonate platform: the Nullarbor Plain, AustraliaJelovčan, Matej (Avtor) Stepišnik, Uroš (Avtor) Šmuc, Andrej (Avtor) Miklavc, Primož (Avtor) Dolenec, Matej (Avtor) Lipar, Matej (Avtor) DayasDolineGeomorphologyHydrologySedimentologyArid karstGISNullarbor PlainDayas are shallow karst depressions that represent one of the most widespread surface landforms in arid karst environments, where present-day dry climatic conditions strongly limit karstification processes. This paper provides a comprehensive geomorphological analysis of dayas on the Nullarbor Plain in southern Australia, one of the world's largest exposed carbonate platforms and an ideal natural laboratory due to its tectonic stability and lack of orogenesis. Semi-automatic GIS-based detection and morphometric analysis were conducted across 11 representative study areas (300 km2 each), complemented by sedimentological analyses (grain-size distribution and XRD). In addition, a GIS-based assessment of water retention in inundated dayas following an extreme flood event in March 2024 was performed by comparing theoretical evaporation losses and observed changes in water volume, supported by meteorological data. Our results demonstrate that palaeotopography exerts a strong control on the spatial distribution and morphometric characteristics of dayas. Additionally, sedimentological analyses indicate a poorly permeable sediment infill resulting from aeolian and fluvial accumulation and reworking, which promotes prolonged surface-water retention within the depressions. Discrepancies between observed water-volume losses and theoretical evaporation indicate partial floodwater infiltration into the karst aquifer, suggesting that dayas may act as focused, event-based recharge features and are not solely relict landforms, but rare surface karst features that remain active under present arid conditions. These findings mark the first application of an integrated methodological approach to the study of dayas and yields new insights into their spatial evolution and geomorphological and hydrological significance on planar carbonate platforms such as the Nullarbor Plain, while offering a framework applicable to analogous arid karst regions worldwide.20262026-06-28 14:52:54Neznano30505UDK: 551.448:551.3.051(94)ISSN pri članku: 0169-555XDOI: 10.1016/j.geomorph.2026.110414COBISS_ID: 282778115sl© 2026 The Authors