The University of Southampton
University of Southampton Institutional Repository

The frequency, magnitude and timing of sediment transport in submarine canyons

The frequency, magnitude and timing of sediment transport in submarine canyons
The frequency, magnitude and timing of sediment transport in submarine canyons
Submarine canyons globally incise 11 % of the seafloor on continental slopes, and provide conduits for sediment and associated particle transport from the shallow marine realm to the deep-sea. Turbidity currents are thought to be the primary mechanism of sediment transport. An individual turbidity current can transport more than ten times the annual sediment for all the world’s rivers at speeds of up to 20 ms−1 . These fast flow velocities coupled with high sediment concentration mean turbidity currents can be destructive; posing a threat to subsea infrastructure. Understanding the frequency, timing and magnitude of turbidity currents (and other mechanisms of sediment transport) is therefore integral to developing our knowledge of particle flux to the deep sea, as well as for geohazard assessments. Despite this, very few measurements of turbidity currents exist, and only over the past decade have technological advancements, such as the use of acoustic Doppler current profilers (ADCPs), been deployed to directly monitor flows in detail. However, deployments are typically of short duration (a few months), use instruments that record at low temporal resolution, or are located distal to the flow source, therefore missing parts of an annual or longer cycles of turbidity current activity. To quantify the frequency and timing of sediment transport in submarine canyons this thesis focuses on unprecedented temporally and spatially extensive geophysical monitoring datasets, specifically using ADCPs in physiographically-diverse settings to show that: (1) Turbidity current activity is primarily controlled by sediment supply. Once sediment is available only minor triggering mechanism are required to initiate a flow; (2) Periods of enhanced turbidity current activity can be anticipated and flow probability is predictable where both sediment supply and triggering mechanism can be quantified; and (3) Even in systems of turbidity current inactivity, the focusing of bottom currents and internal submarine canyon tides are capable of transporting particles to the deep-sea. These findings highlight the highly active and complex nature of sediment transport in submarine canyons.
University of Southampton
Bailey, Lewis
9024caec-0341-4983-ad1e-e3a23e6d132e
Bailey, Lewis
9024caec-0341-4983-ad1e-e3a23e6d132e
Clare, Michael
b26da858-9c08-4784-aaa9-7092efcd94bd

Bailey, Lewis (2022) The frequency, magnitude and timing of sediment transport in submarine canyons. University of Southampton, Doctoral Thesis, 164pp.

Record type: Thesis (Doctoral)

Abstract

Submarine canyons globally incise 11 % of the seafloor on continental slopes, and provide conduits for sediment and associated particle transport from the shallow marine realm to the deep-sea. Turbidity currents are thought to be the primary mechanism of sediment transport. An individual turbidity current can transport more than ten times the annual sediment for all the world’s rivers at speeds of up to 20 ms−1 . These fast flow velocities coupled with high sediment concentration mean turbidity currents can be destructive; posing a threat to subsea infrastructure. Understanding the frequency, timing and magnitude of turbidity currents (and other mechanisms of sediment transport) is therefore integral to developing our knowledge of particle flux to the deep sea, as well as for geohazard assessments. Despite this, very few measurements of turbidity currents exist, and only over the past decade have technological advancements, such as the use of acoustic Doppler current profilers (ADCPs), been deployed to directly monitor flows in detail. However, deployments are typically of short duration (a few months), use instruments that record at low temporal resolution, or are located distal to the flow source, therefore missing parts of an annual or longer cycles of turbidity current activity. To quantify the frequency and timing of sediment transport in submarine canyons this thesis focuses on unprecedented temporally and spatially extensive geophysical monitoring datasets, specifically using ADCPs in physiographically-diverse settings to show that: (1) Turbidity current activity is primarily controlled by sediment supply. Once sediment is available only minor triggering mechanism are required to initiate a flow; (2) Periods of enhanced turbidity current activity can be anticipated and flow probability is predictable where both sediment supply and triggering mechanism can be quantified; and (3) Even in systems of turbidity current inactivity, the focusing of bottom currents and internal submarine canyon tides are capable of transporting particles to the deep-sea. These findings highlight the highly active and complex nature of sediment transport in submarine canyons.

Text
PhD thesis Bailey - Version of Record
Restricted to Repository staff only until 27 May 2024.
Available under License University of Southampton Thesis Licence.
Text
Permission to deposit thesis - Lewis Bailey
Restricted to Repository staff only
Available under License University of Southampton Thesis Licence.

More information

Submitted date: 30 June 2022

Identifiers

Local EPrints ID: 467734
URI: http://eprints.soton.ac.uk/id/eprint/467734
PURE UUID: 7ee7d787-0340-4a10-82d5-3188df61584b

Catalogue record

Date deposited: 21 Jul 2022 16:52
Last modified: 23 Jul 2022 00:46

Export record

Contributors

Author: Lewis Bailey
Thesis advisor: Michael Clare

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×