A numerical model for fine suspended sediment transport in the southwest lagoon of New Caledonia

Douillet, Pascal; Ouillon, Sylvain; Cordier, Emmanuel

doi:10.1007/s00338-001-0193-6

Cited by 106 publications

(76 citation statements)

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“…For the cohesive sediments, if the bed shear stress is larger than a critical value, erosion is modeled following the Partheniades' formulation [66], whereas if the bed shear stress is less than a critical value for deposition, Krone's formula [67] is used to quantify the deposition flux. The parameters required to simulate the cohesive sediment transport include critical bed shear stresses for erosion τ cre and deposition τ crd , the erosion parameter M and the particle settling velocity w s [68]. After calibration, τ crd was set to 1000 N¨m´2, which effectively implied that deposition was a function of concentration and fall velocity [69].…”

Section: Model Setupmentioning

confidence: 99%

Numerical Simulations of Suspended Sediment Dynamics Due to Seasonal Forcing in the Mekong Coastal Area

Vinh¹,

Ouillon

Thao³

et al. 2016

Water

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Abstract:The Mekong River is ranked as the 8th in terms of water discharge and as the 10th in terms of sediment load in the world. During the last 4500 years, its delta prograded more than 250 km to the south due to a tremendous amount of sediments deposited, and turned from a "tide-dominated" delta into a "wave-and-tide dominated" delta. This study aims at completing our knowledge on the fate of sediments that may be stored in estuarine or coastal systems, or dispersed over the continental shelf and slope. Sediment transport in the Mekong River Delta (MRD) coastal area was studied by numerical simulations using the Delft3D model. The model configuration was calibrated and validated from data collected in situ during 4 periods from 2012 to 2014. Then, 50 scenarios corresponding to different wave conditions (derived from the wave climate) and river discharge values typical of low flow and flood seasons enabled us to quantify the dispersal patterns of fluvial sediments close to the mouths and along the coast. Sediments mostly settled in the estuary and close to the mouths under calm conditions, and suspended sediment with higher concentrations extend further offshore with higher waves. Waves from the Southeast enhanced the concentration all along the MRD coastal zone. Waves from the South and Southwest induced coastal erosion, higher suspended sediment concentrations in front of the southern delta, and a net transport towards the Northeast of the delta. Because of episodes of Southern and Southwestern waves during the low flow season, the net alongshore suspended sediment transport is oriented Northeastward and decreases from the Southwestern part of the coastal zone (~960ˆ10 3 t yr´1) to the Northeastern part (~650ˆ10 3 t yr´1).

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Section: Model Setupmentioning

confidence: 99%

Numerical Simulations of Suspended Sediment Dynamics Due to Seasonal Forcing in the Mekong Coastal Area

Vinh¹,

Ouillon

Thao³

et al. 2016

Water

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“…Le vent et la marée sont les éléments moteurs principaux des courants dans le LSNC [4]. La marée semi-diurne se propage du sud vers le nord.…”

Section: Hydrodynamique Côtièreunclassified

“…Main circulation patterns have been deduced from extensive currentmeter and tidegauge measurements and from 2D and 3D hydrodynamic models [4]. Wind and tidal forcings are the main mechanisms driving the lagoon circulation.…”

Section: Hydrodynamicsmentioning

confidence: 99%

Enhancement of regional variations in salinity and temperature in a coral reef lagoon, New Caledonia

Ouillon

Douillet

Fichez

et al. 2005

Comptes Rendus. Géoscience

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The variability in salinity and temperature in the southwest lagoon of New Caledonia (2,100 km 2 ) under non-storm conditions is analyzed using a 4-year data set (1997)(1998)(1999)(2000)(2001). Seasonal and interannual variations in salinity are amplified near shore.Temperature is larger in bays than in the open lagoon during summer, the reverse is true in winter. El Niño Southern Oscillation (ENSO) related nearshore temperature variations parallel those at regional scale, but with seasonal variations amplified. Haline stratification, if any, is enhanced in coastal areas. RésuméLes distributions de salinité et de température dans le lagon sud-ouest de NouvelleCalédonie (2100 km 2 ) sont analysées en regard de leurs variations régionales à partir de 4 ans de mesures (1997)(1998)(1999)(2000)(2001). Les variations saisonnières et interannuelles de salinité sont amplifiées à la côte. La température est plus élevée près de la côte qu'en milieu de lagon en été austral et y est plus faible en hiver. Le phénomène ENSO (El Niño Southern Oscillation) amplifie ces variations. En cas de stratification haline, celle-ci est également amplifiée à la côte. Les baies jouent ainsi un rôle de caisse de résonance dans le fonctionnement physique du lagon, avec des répercussions tant dans la répartition des espèces que dans la vulnérabilité des milieux (blanchissement des coraux).

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“…The physical mechanisms driving circulation of coral reef-lagoons systems and lagoon-ocean exchange can influence the transport, dispersal, and retention of larval fish, corals, and other invertebrates (Dight et al 1990;Black 1993;Cowen et al 2000), the supply of nutrients (Hatcher 1997;Falter et al 2004), phytoplankton (Yahel et al 1998), and zooplankton (Yahel et al 2005) to the reef, as well as the flow of sediment from the watersheds connected to reef lagoons (Douillet et al 2001). These physical mechanisms can span a wide range of scales, ranging from an individual coral colony to the reef, island, and basin scale (Monismith 2007).…”

mentioning

confidence: 99%

Episodic circulation and exchange in a wave‐driven coral reef and lagoon system

Hench

Leichter

Monismith

2008

Limnology & Oceanography

193

224

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We examined the role of wave-driven circulation relative to wind and buoyancy forcing in a coral reef-lagoon system. Circulation measurements in Paopao Bay, Moorea, French Polynesia, during austral summer show the importance of waves in driving flows over the reef crest, through the lagoon, and out the reef pass. Tides were comparatively weak, due to proximity to amphidromic points, and exhibited an unusual spring-neap cycle where the major lunar tide modulated the major solar tide, and the overall tidal phase stayed approximately constant. Wind had only a secondary effect compared to surface waves. A simple fluid mass balance indicated rapid flushing of the shallow back reef and export through the reef pass, and a reef capture zone width of ,2.3 km. The reef pass circulation dynamics exhibited two-layer baroclinic exchange flow when waves were small, which was suppressed during large wave events. The unusually weak tidal forcing provided an opportunity to more closely investigate wave-driven circulation dynamics. As expected theoretically, there was a wave-driven setup of the free surface across the shallow lagoon, which drove a highly frictional flow, evident by a large drag coefficient C D < 0.1. Diverging from extant theory, the observed setup varied strongly with significant wave height and period. Overall, the circulation and exchange between this coral reef system and the adjacent open ocean were largely determined by episodic remote-forcing events and differed significantly from periodic tidal-exchange mechanisms.

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A numerical model for fine suspended sediment transport in the southwest lagoon of New Caledonia

Cited by 106 publications

References 0 publications

Numerical Simulations of Suspended Sediment Dynamics Due to Seasonal Forcing in the Mekong Coastal Area

Numerical Simulations of Suspended Sediment Dynamics Due to Seasonal Forcing in the Mekong Coastal Area

Enhancement of regional variations in salinity and temperature in a coral reef lagoon, New Caledonia

Episodic circulation and exchange in a wave‐driven coral reef and lagoon system

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