Rules of river avulsion change downstream.

Autor: Gearon JH; Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN, USA. jake.gearon@gmail.com., Martin HK; Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN, USA.; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA., DeLisle C; Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN, USA., Barefoot EA; Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN, USA.; Department of Earth and Planetary Sciences, University of California, Riverside, Riverside, CA, USA., Mohrig D; Department of Earth and Planetary Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA., Paola C; Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA., Edmonds DA; Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN, USA.
Jazyk: angličtina
Zdroj: Nature [Nature] 2024 Oct; Vol. 634 (8032), pp. 91-95. Date of Electronic Publication: 2024 Sep 18.
DOI: 10.1038/s41586-024-07964-2
Abstrakt: Avulsing rivers create new pathways on the floodplain and the associated flooding can profoundly affect society 1-4 . River avulsions are thought to occur when the water column becomes perched above the floodplain 5 or when the slope down the flanks of the channel provides a steeper descent than the existing river channel 6,7 . We test these classical ideas by quantifying the topography around avulsing rivers and show that these mechanisms, historically invoked separately, work together. Near coasts, rivers avulse when the slope away from the channel is steeper, not because they are perched. The opposite is true near mountain fronts; on fans, the alternative paths are similarly steep to the downstream path, so rivers avulse when they are perched above the surrounding landscape. We reconcile these findings and present a new theoretical framework that identifies which rivers are vulnerable to avulsion and predicts the path of an avulsing river. These first-order rules of avulsion suggest that avulsion risks are underestimated in many coastal environments 8 and that probabilistic predictions of avulsion pathfinding can efficiently map hazards with minimal information. Applying these principles for risk assessment could particularly benefit the Global South, which is disproportionately affected by avulsions.
(© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)
Databáze: MEDLINE
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