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Development of alpine flow regimes in Austria in the period 1961–2010

Lebiedzinski, Katharina, Fürst, Josef
Österreichische Wasser- und Abfallwirtschaft 2018 v.70 no.9-10 pp. 474-484
anthropogenic activities, cluster analysis, gauges, rivers, runoff, streams, temporal variation, topography, Austria
The seasonal runoff characteristics in Alpine rivers have changed during the last decades. The present study deals with the investigation of temporal changes and spatial distribution of seasonal flow characteristics by identifying and describing flow regimes. Mean monthly flows at 280 stream gauges without significant anthropogenic influences in Austria were analyzed for the period 1961–2010. A cluster analysis was used to define five representative flow regime groups with glacial, nival, pluvial and nivo-pluvial characteristics, respectively. Although both topographic and hydrological conditions in Austria are highly heterogeneous, the spatial distribution shows a clear pattern.The alpine region was dominated by nival and glacial flow regimes, while the lowland and hilly region in the northeast was dominated by pluvial flow regimes. The temporal development showed a significant increase of pluvial characteristics over time, responding differently at mean seasonal flows north and south of the Alpine divide.The observed changes in the flow regimes were consistent with seasonal trends in precipitation, discharge and the water balance as published in the Hydrologic Atlas of Austria. The study provides new information about the temporal development and the current state of mean seasonal flow characteristics, that is of particular interest considering predicted changes of factors and processes influencing flow generation.