Dataset Information

Longest sediment flows yet measured show how major rivers connect efficiently to deep sea.

ABSTRACT: Here we show how major rivers can efficiently connect to the deep-sea, by analysing the longest runout sediment flows (of any type) yet measured in action on Earth. These seafloor turbidity currents originated from the Congo River-mouth, with one flow travelling >1,130 km whilst accelerating from 5.2 to 8.0 m/s. In one year, these turbidity currents eroded 1,338-2,675 [>535-1,070] Mt of sediment from one submarine canyon, equivalent to 19-37 [>7-15] % of annual suspended sediment flux from present-day rivers. It was known earthquakes trigger canyon-flushing flows. We show river-floods also generate canyon-flushing flows, primed by rapid sediment-accumulation at the river-mouth, and sometimes triggered by spring tides weeks to months post-flood. It is demonstrated that strongly erosional turbidity currents self-accelerate, thereby travelling much further, validating a long-proposed theory. These observations explain highly-efficient organic carbon transfer, and have important implications for hazards to seabed cables, or deep-sea impacts of terrestrial climate change.

SUBMITTER: Talling PJ

PROVIDER: S-EPMC9297676 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature

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Longest sediment flows yet measured show how major rivers connect efficiently to deep sea.

Talling Peter J PJ Baker Megan L ML Pope Ed L EL Ruffell Sean C SC Jacinto Ricardo Silva RS Heijnen Maarten S MS Hage Sophie S Simmons Stephen M SM Hasenhündl Martin M Heerema Catharina J CJ McGhee Claire C Apprioual Ronan R Ferrant Anthony A Cartigny Matthieu J B MJB Parsons Daniel R DR Clare Michael A MA Tshimanga Raphael M RM Trigg Mark A MA Cula Costa A CA Faria Rui R Gaillot Arnaud A Bola Gode G Wallance Dec D Griffiths Allan A Nunny Robert R Urlaub Morelia M Peirce Christine C Burnett Richard R Neasham Jeffrey J Hilton Robert J RJ

Nature communications 20220720 1

Here we show how major rivers can efficiently connect to the deep-sea, by analysing the longest runout sediment flows (of any type) yet measured in action on Earth. These seafloor turbidity currents originated from the Congo River-mouth, with one flow travelling >1,130 km whilst accelerating from 5.2 to 8.0 m/s. In one year, these turbidity currents eroded 1,338-2,675 [>535-1,070] Mt of sediment from one submarine canyon, equivalent to 19-37 [>7-15] % of annual suspended sediment flux from prese ...[more]

PMID: 35858962

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Project description:More than a century of dam construction and water development in the western United States has led to extensive ecological alteration of rivers. Growing interest in improving river function is compelling practitioners to consider ecological restoration when managing dams and water extraction. We developed an Ecological Response Model (ERM) for the Cache la Poudre River, northern Colorado, USA, to illuminate effects of current and possible future water management and climate change. We used empirical data and modeled interactions among multiple ecosystem components to capture system-wide insights not possible with the unintegrated models commonly used in environmental assessments. The ERM results showed additional flow regime modification would further alter the structure and function of Poudre River aquatic and riparian ecosystems due to multiple and interacting stressors. Model predictions illustrated that specific peak flow magnitudes in spring and early summer are critical for substrate mobilization, dynamic channel morphology, and overbank flows, with strong subsequent effects on instream and riparian biota that varied seasonally and spatially, allowing exploration of nuanced management scenarios. Instream biological indicators benefitted from higher and more stable base flows and high peak flows, but stable base flows with low peak flows were only half as effective to increase indicators. Improving base flows while reducing peak flows, as currently proposed for the Cache la Poudre River, would further reduce ecosystem function. Modeling showed that even presently depleted annual flow volumes can achieve substantially different ecological outcomes in designed flow scenarios, while still supporting social demands. Model predictions demonstrated that implementing designed flows in a natural pattern, with attention to base and peak flows, may be needed to preserve or improve ecosystem function of the Poudre River. Improved regulatory policies would include preservation of ecosystem-level, flow-related processes and adaptive management when water development projects are considered.

Dataset Information

Longest sediment flows yet measured show how major rivers connect efficiently to deep sea.

Publications

Longest sediment flows yet measured show how major rivers connect efficiently to deep sea.

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