Currents in Submarine Canyons: An Air-Sea-Land Interaction

Inman, Douglas L.; Nordstrom, Charles E.; Flick, Reinhard E.

doi:10.1146/annurev.fl.08.010176.001423

Cited by 225 publications

(151 citation statements)

References 42 publications

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“…The challenges of selecting locations where turbidity currents are frequent and designing instruments that can make the necessary measurements are well known (Inman et al 1976;Talling et al 2013). The flows evolve significantly, such that source-to-sink data are needed.…”

Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

166

117

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Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than , 0.6u. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (, 0.1%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces

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Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

166

117

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“…Submarine canyons receive macrophyte detritus and other bedload debris onginally deposited on wide areas of the coastline by intercepting material transported along the shore by wave energy (Inman & Frautschy 1965, Shepard & Dill 1966, Inman & Bruch 1973. This is especially true for canyons with shallow heads; however, large accumulations of kelp detritus have also been reported from offshore canyons (BBA & ROS 1986).…”

Section: Introductionmentioning

confidence: 99%

“…Canyons located near macrophyte communities, such as forests of the giant kelp Macrocystis pyrifera, are likely to be highly organically ennched because of the high productivity of this species (Foster & Schiel 1985) and the large proportion of that production which is exported (Zobel1 1959, Gerard 1976. Once in canyons, detntus is transported deeper by continuous processes, such as periodic resuspension by tidal flows, and by violent episodic events, such as slumps and turbidity currents (Shepard 1973, Inman et al 1976, Gardner 1989. Organic aggregates channeled to the deep-sea through submarine canyons may provide habitat for fishes and increase their invertebrate prey populations through elevated benthic secondary production.…”

Section: Introductionmentioning

confidence: 99%

Organic enrichment by macrophyte detritus, and abundance patterns of megafaunal populations in submarine canyons

Vetter¹,

Dayton²

1999

Mar. Ecol. Prog. Ser.

187

128

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Submanne canyons can provide large quantities of food in aggregated form on the deepsea floor by acting as conduits for manne macrophyte production produced in the intertidal and shallow subtidal zone. Longshore transport dehvers substantial quantities of macrophyte detntus fronl surfgrass Phyllospadix lorreyi, kelps Macrocystis pyrifera and Egregia menziesii, and other macroalgae to the heads of Scripps and La Jolla Submarine Canyons. Strong tidal and gravity currents distribute this material throughout much of the canyon System, where it is utilized as food and habitat by benthic fauna. Video data taken from remotely operated vehicles and submarines were used to evaluate differences in detrital Cover and megafaunal abundance In the canyons, and at nearby reference Stations.Within the canyons dense mats of detntus were common down to 550 m, and M. pyrifera holdfasts were observed at 700 and 900 m. Virtually no dnft material was observed out of the canyons. Comparisons of megafaunal invertebrates in and out of the canyons revealed generally higher densities at noncanyon sites due to large numbers of urchins. Species richness of all megafauna and abundance of nonurchin megafauna were greater in the canyons than out. It is likely that urchin abundance in canyons is reduced through disturbance by currents and detrital flows in the canyons. Species nchness and abundance of fishes were greater in the canyons at all depths for which comparative data were available (100 to 500 m). From 150 to 200 m in Scripps Canyon, juvenile Pacific hake Merlucciusproductus were so abundant at tirnes that their bodies obscured visibility. Turbot Pleuronichfhys sp. and zoarcids Lycodes pacifica were also abundant in Scripps Canyon from 100 to 300 m. Data from this study support the hypotheses that macrophyte detntus Covers large areas of the La JoLla and Scripps Canyon axis, and that megafaunal abundance 1s associated with detritus at both large and small spatial scales

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“…[5] Although previous observations suggest that nearshore submarine canyons may have a strong effect on the distribution of infragravity wave energy [Inman et al, 1976;Huntley et al, 1981], most wave propagation models account only for refraction over smooth changes in bathymetry [e.g., Munk and Traylor, 1947;O'Reilly and Guza, 1993]. Here a refraction-only model is shown to have relatively poor skill predicting the infragravity energy observed near two steep submarine canyons on the southern California inner shelf.…”

Section: Introductionmentioning

confidence: 94%

Refraction and reflection of infragravity waves near submarine canyons

Thomson¹,

Elgar²,

Herbers³

et al. 2007

J. Geophys. Res.

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[1] The propagation of infragravity waves (ocean surface waves with periods from 20 to 200 s) over complex inner shelf (water depths from about 3 to 50 m) bathymetry is investigated with field observations from the southern California coast. A waveray-path-based model is used to describe radiation from adjacent beaches, refraction over slopes (smooth changes in bathymetry), and partial reflection from submarine canyons (sharp changes in bathymetry). In both the field observations and the model simulations the importance of the canyons depends on the directional spectrum of the infragravity wave field radiating from the shoreline and on the distance from the canyons. Averaged over the wide range of conditions observed, a refraction-only model has reduced skill near the abrupt bathymetry, whereas a combined refraction and reflection model accurately describes the distribution of infragravity wave energy on the inner shelf, including the localized effects of steep-walled submarine canyons.

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Currents in Submarine Canyons: An Air-Sea-Land Interaction

Cited by 225 publications

References 42 publications

Key Future Directions For Research On Turbidity Currents and Their Deposits

Key Future Directions For Research On Turbidity Currents and Their Deposits

Organic enrichment by macrophyte detritus, and abundance patterns of megafaunal populations in submarine canyons

Refraction and reflection of infragravity waves near submarine canyons

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