Flow and depositional response of turbidity currents to complex canyon topographies: A numerical simulation perspective

Lu，Yang1; Liu，Xiaolei1,2; Yang，Yuping3; Wang，Dawei4; Yu，Heyu1; Zhang，Shaopeng1; Xie，Xiaotian1; Guo，Xingsen1,5

2024-12-01

10.1016/j.geomorph.2024.109437

Geomorphology   影响因子和分区

0169-555X

Submarine canyons are prominent features on continental margins, acting as major conduits for sediment transport primarily through turbidity currents. Understanding how these currents interact with complex canyon topographies is crucial for deciphering the canyon system evolution, yet challenging due to limited field observations. Focusing on a group of slope-confined canyons within the Pearl River Mouth Basin, northern South China Sea, this study integrates multibeam bathymetry, core analysis, and process-based Computational Fluid Dynamics (CFD) modeling to investigate the influence of realistic canyon topography on turbidity current dynamics and resulting sediment deposition. Analysis of core samples revealed a potential turbidite layer characterized by silts and sandy silts. Using these sediment information and bathymetric data, we conducted a series of three-dimensional CFD simulations. Our findings highlight the significant variability in turbidity current characteristics, particularly flow velocity and sediment concentration, within the canyon groups. This variability is primarily controlled by canyon head depth, the width-to-relief ratio, and slope gradients. Notably, the simulations revealed unique flow structures not typically observed in experimental settings, including unidirectional flows, small-scale helical flows, stacked and mixed flow cells, and flow separation and convergence across inter-canyon ridges. Our CFD simulations also revealed a distinct near-wall pattern of linear deposition of coarse-grained sediments, which is similar to the observed bathymetric changes between 2009 and 2017. Based on the consistent results, we propose a conceptual model wherein differential erosion, driven by oceanographic processes, plays a key role in shaping the observed linear depositional patterns.

CFD simulations Flow structures Linear deposition Slope-confined canyons Turbidity currents

英语

其他

2-s2.0-85205420145

Scopus

1.Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering,Ocean University of China,Qingdao,266100,China
2.Laboratory for Marine Geology,Qingdao Marine Science and Technology Center,Qingdao,266237,China
3.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
4.Institute of Deep-Sea Science and Engineering,Chinese Academy of Sciences,Sanya,572000,China
5.Department of Civil,Environmental and Geomatic Engineering,University College London,London,WC1E 6BT,United Kingdom

Lu，Yang,Liu，Xiaolei,Yang，Yuping,et al. Flow and depositional response of turbidity currents to complex canyon topographies: A numerical simulation perspective[J]. Geomorphology,2024,466.

Lu，Yang.,Liu，Xiaolei.,Yang，Yuping.,Wang，Dawei.,Yu，Heyu.,...&Guo，Xingsen.(2024).Flow and depositional response of turbidity currents to complex canyon topographies: A numerical simulation perspective.Geomorphology,466.

Lu，Yang,et al."Flow and depositional response of turbidity currents to complex canyon topographies: A numerical simulation perspective".Geomorphology 466(2024).