Earth Surf. Dynam., 8, 69–85, 2020 https://doi.org/10.5194/esurf-8-69-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. The destiny of orogen-parallel streams in the Eastern Alps: the Salzach–Enns drainage system Georg Trost1, Jörg Robl2, Stefan Hergarten3, and Franz Neubauer2 1Department of Geoinformatics, Paris Lodron University of Salzburg, 5020 Salzburg, Austria 2Department of Geography and Geology, Paris Lodron University of Salzburg, 5020 Salzburg, Austria 3Institute of Earth and Environmental Sciences, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany Correspondence: Georg Trost (
[email protected]) Received: 1 August 2019 – Discussion started: 7 August 2019 Revised: 7 November 2019 – Accepted: 3 January 2020 – Published: 28 January 2020 Abstract. The evolution of the drainage system in the Eastern Alps is inherently linked to different tectonic stages of the alpine orogeny. Crustal-scale faults imposed eastward-directed orogen-parallel flow on major rivers, whereas late orogenic surface uplift increased topographic gradients between the foreland and range and hence the vulnerability of such rivers to be captured. This leads to a situation in which major orogen-parallel alpine rivers such as the Salzach River and the Enns River are characterized by elongated east–west-oriented catchments south of the proposed capture points, whereby almost the entire drainage area is located west of the capture point. To determine the current stability of drainage divides and to predict the potential direction of divide migration, we analysed their geometry at catchment, headwater and hillslope scale covering timescales from millions of years to the millennial scale.