A landscape evolution model of how uplift has shaped drainage patterns in Central Europe

The large-scale reorganization of drainage patterns is one of the most enigmatic events in the landscape history of Central Europe. In particular, the rivers Main and Neckar show a reversal of the flow direction from southeast to northwest. Historically, this has been interpreted as a consequence of the subsidence of the Upper Rhine Graben (URG) and the subsequent lowering of the base level. However, the high uplift rates along the shoulders of the URG, which suggest an increased southeastward tilt, raise questions. This prompts the investigation of alternative uplift patterns contributing to the observed river reversals.

This study uses a new version of the landscape evolution model TTLEM and river analyses with TopoToolbox to investigate the potential role of large-scale lithospheric folding resulting from the collision of the Alps. Our research challenges the conventional narrative by examining whether such folding could be a driving force behind the enigmatic flow reversals in the Main and Neckar rivers.

During the transition from the Cretaceous to the Paleocene, a dome-shaped exhumation event in Europe led to the establishment of a radial river network originating in higher regions. Some rivers still have their original flow directions, such as the Wörnitz and the Brenz, or the Neckar, which now flows in the opposite direction. In southern Germany, a network of rivers flowed in a southward or southeastward direction. The Eocene marked the beginning of the formation of the URG, accompanied by a marked uplift of the Graben shoulders and a tilting of southern Germany to the east-southeast. During this period, the flow directions of the rivers remained constant, and the sinking URG initially failed to extend its drainage basin beyond the graben shoulders.

The pivotal moment in the redirection of the rivers has been evident since the Miocene when lithospheric folding occurs parallel to the Alpine front. This previously unnoticed event highlights a crucial link between the collision of the Alps and the redirection of the Main and Neckar rivers. Our findings shed light on the complex interplay of tectonic forces, landscape evolution, and river dynamics, challenging existing paradigms and contributing to a deeper understanding of the geomorphic history of Central Europe.