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TitleRapidly-migrating and internally-generated knickpoints can control submarine channel evolution
AuthorHeijnen, M S; Clare, M A; Cartingy, M J B; Talling, P J; Hage, S; Lintern, D GORCID logo; Stacey, CORCID logo; Parsons, D R; Simmons, S M; Chen, Y; Sumner, E J; Dix, J K; Hughes Clarke, J E
SourceNature Communications vol. 11, issue 1, 3129, 2020 p. 1-15, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200101
PublisherNature Research
Mediapaper; on-line; digital
File formatpdf; html
ProvinceBritish Columbia
NTS92K/02; 92K/03; 92K/06; 92K/07; 92K/10; 92K/11; 92K/14; 92K/15; 92N/02; 92N/03
AreaBute Inlet
Lat/Long WENS-125.3008 -124.5864 51.0239 50.2156
Subjectsmarine geology; sedimentology; Science and Technology; submarine features; channels; marine sediments; bedforms; geological evolution; erosion; bathymetry
Illustrationslocation maps; geoscientific sketch maps; profiles; models; schematic representations; 3-D models
Released2020 06 19; 2020 09 01
AbstractSubmarine channels are the primary conduits for terrestrial sediment, organic carbon, and pollutant transport to the deep sea. Submarine channels are far more difficult to monitor than rivers, and thus less well understood. Here we present 9 years of time-lapse mapping of an active submarine channel along its full length in Bute Inlet, Canada. Past studies suggested that meander-bend migration, levee-deposition, or migration of (supercritical-flow) bedforms controls the evolution of submarine channels. We show for the first time how rapid (100-450 m/year) upstream migration of 5-to-30 m high knickpoints can control submarine channel evolution. Knickpoint migration-related changes include deep (>25 m) erosion, and lateral migration of the channel. Knickpoints in rivers are created by external factors, such as tectonics, or base-level change. However, the knickpoints in Bute Inlet appear internally generated. Similar knickpoints are found in several submarine channels worldwide, and are thus globally important for how channels operate.
Summary(Plain Language Summary, not published)
This study investigates submarine channels in Bute Inlet, Canada, which are like underwater highways that transport sediments, organic matter, and pollutants from land to the deep sea. These channels are hard to study, but this research provides nine years of monitoring data to understand their behavior.
Traditionally, scientists believed that features like meander bends or deposits called levees controlled how submarine channels change over time. However, this study reveals a new factor: rapid upstream migration of knickpoints, which are abrupt changes in the channel's elevation. These knickpoints can move upstream at speeds ranging from 100 to 450 meters per year, eroding the channel's bottom and shifting its position.
In rivers, knickpoints are usually caused by external factors like tectonic movements or changes in water levels. However, the knickpoints in Bute Inlet seem to be generated within the channel itself, a unique finding. This research suggests that similar knickpoints are present in submarine channels worldwide, changing our understanding of how these channels evolve.
Understanding these processes is essential because submarine channels play a crucial role in transporting materials from land to the deep sea, and their behavior can impact ecosystems and sediment movement.

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