| Summary: | The thawing of alpine permafrost in a warmer climate may alter the runoff regime of high alpine catchments. We present a case study where detailed geophysical and geological field investigations were performed in a 5 km2 large catchment in Western Austria to assess its main hydrogeological settings. Ground-penetrating radar data, seismic refraction measurements and ground-surface-temperature data were employed to map the spatial permafrost distribution and depth of the permafrost table and the bedrock interface. The results for different types of unconsolidated sediments were then translated into five sets of flow path concepts in the presence and absence of permafrost. These concepts were then used to set up a rainfall-runoff model and simulate the runoff response of the catchment for scenarios with and without permafrost. The simulations indicate that the complete thawing of permafrost will increase the catchment storage capacity which will reduce the flood peaks by up to 20% and increase runoff during recession by about 15%. The reduction of extreme events is important since it may also affect flood events in downstream catchments. The study highlights the importance of interdisciplinary work between hydrology, geophysics and geology which can greatly help to improve the understanding of subsurface processes.
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