Greater Alpine river network evolution, interpretations based on novel drainage analysis.

The Central European drainage system is dominated by four major rivers (the Danube, Rhine, Rhône and Po). The geometry of these drainage basins has evolved through the history of Alpine and Carpathian orogeny. Analysis of the modern river geometry reveals the geometric stability or instability of the drainage network and enables interpretation of the erosion and exhumation pattern. We characterize the river basin geometry and inter-basin relief through metrics including the quantity χ that relates to the catchment area, and a catchment restricted minimum elevation (CRM) metric. The interpretations from the maps are in agreement with known river captures and morphological features. The χ-map reveals additional systematic, large-scale transients, consistent with ongoing basin changes, mainly manifesting in the Danube losing catchment area. We postulate that the changes are related to the longitudinal initiation of the Danube River in the Alpine foreland, augmented by the formation of the Carpathians and the filling of the Pannonian Basin, which resulted in an elongation of the Danube river basin. We conclude that the Danube has lacked erosional power throughout its history and therefore been victim to capture and area loss.