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Narrower Paleo-Canyons Downsize Megafloods

David, S. R. and Larsen, I. J. and Lamb, M. P. (2022) Narrower Paleo-Canyons Downsize Megafloods. Geophysical Research Letters, 49 (11). Art. No. e2022GL097861. ISSN 0094-8276. doi:10.1029/2022gl097861.

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Catastrophic drainage of glacial Lake Missoula through the Columbia River Gorge, USA, produced some of the largest floods ever known. However, erosion of the gorge during flooding has not been quantified, hindering discharge reconstructions and our understanding of landscape change by megafloods. Using a neural network and geomorphic observations, we reconstructed the gorge topography and found ∼7.4 km³ of rock was eroded from gorge walls. Accounting for a narrower canyon and matching flood high-water marks resulted in peak-flood discharge reconstructions of 6 × 10⁶–7 × 10⁶ m³ s⁻¹, which are 30%–40% lower than prior estimates based on the present-day topography. Sediment transport modeling indicated that more frequent intermediate-sized floods transported most of the eroded rock. Thus, similar to alluvial rivers, discharge magnitude-frequency tradeoffs may also govern canyon formation by repeated megafloods.

Item Type:Article
Related URLs:
URLURL TypeDescription Information, models, and analysis scripts Item10-m DEM data ItemENC data ItemLIDAR data ItemLIDAR data
David, S. R.0000-0003-2708-4251
Larsen, I. J.0000-0003-3094-4830
Lamb, M. P.0000-0002-5701-0504
Additional Information:© 2022 American Geophysical Union. Issue Online: 07 June 2022; Version of Record online: 07 June 2022; Accepted manuscript online: 27 May 2022; Manuscript accepted: 25 May 2022; Manuscript revised: 19 May 2022; Manuscript received: 12 January 2022. The authors thank Jürgen Mey for sharing the ANN code, Jim O’Connor for constructive comments and for sharing high-water mark data, Karin Lehnigk for helpful conversations, and three anonymous reviewers for constructive comments. This research was supported by a collaborative National Science Foundation grant (1529528, 1529110) to I.J.L and M.P.L. Data Availability Statement: Data, models, and analysis scripts are available via the University of Massachusetts ScholarWorks data repository ( The 10-m digital elevation model data are available at: and the electronic navigation chart data are at: The lidar data can be acquired at and
Funding AgencyGrant Number
Subject Keywords:Columbia Gorge; Megafloods; Missoula floods
Issue or Number:11
Record Number:CaltechAUTHORS:20220531-843950000
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Official Citation:David, S. R., Larsen, I. J., & Lamb, M. P. (2022). Narrower paleo-canyons downsize megafloods. Geophysical Research Letters, 49, e2022GL097861.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114968
Deposited By: George Porter
Deposited On:01 Jun 2022 16:56
Last Modified:30 Jun 2022 18:48

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