Hyperconcentrated flows shape bedrock channels

Verena Stammberger, Benjamin Jacobs, Michael Krautblatter

Research output: Contribution to journalArticlepeer-review

Abstract

Geomorphological evidence of incised bedrock channels is widespread in all mountain landscapes worldwide. However, the processes controlling incision and gorge formation in bedrock have not directly been observed in an actualistic way. Here, we show a LiDAR change detection deciphering the erosive power of a 60,000 m3 hyperconcentrated flow (transition between flood and debris flow) in a deeply incised rock gorge in June, 2020. The flow laterally eroded up to 1 m of massive limestone and widened a 4 m narrow section of the gorge by up to 15%. Sinuosity, convergence, and gradient of the channel were proven to not influence erosivity indicating the hyperconcentrated nature of erosion. Furthermore, other than in prior studies no abrasion of thin rock veneer dominates erosion but mechanically excited breakout of rock fragments. Magnitude-frequency relations of eroded volumes mimic subaerial rock wall retreat. We show how single hyperconcentrated flows can erode bedrock channels far more efficient than decades of turbulent flows and hypothesise that repeated hyperconcentrated flows in phases of enhanced precipitation or by elevated material supply could control erosion boosts in gorge formation, e.g. in the Lateglacial or during climatic fluctuations.

Original languageEnglish
Article number184
JournalCommunications Earth and Environment
Volume5
Issue number1
DOIs
StatePublished - Dec 2024

Fingerprint

Dive into the research topics of 'Hyperconcentrated flows shape bedrock channels'. Together they form a unique fingerprint.

Cite this