Numerical study of circulation on the inner Amazon Shelf

Fontes, Roberto Fioravanti Carelli; Castro, Belmiro Mendes de; Beardsley, Robert C.

doi:10.1007/s10236-008-0139-4

Cited by 29 publications

(20 citation statements)

References 21 publications

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“…The dynamics of plumes in near‐equatorial regions have been minimally documented. Previous studies of low‐latitude continental shelves are mainly concentrated on the Amazon river plume [ Lentz , ; Nikiema et al ., ; Fontes et al ., ; Salisbury et al ., ], where the river discharge is very large and has major effects on the coastal hydrography. There is little knowledge about the spatial and temporal variability of smaller river plumes in near‐equatorial regions.…”

Section: Introductionmentioning

confidence: 98%

Wind forcing controls on river plume spreading on a tropical continental shelf

2015

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The Berau Continental Shelf is located close to the Equator in the Indonesian Archipelago, hosting a complex of coral reefs along its oceanic edge. The Berau coral reefs have a very high biodiversity, but the area is under serious risk due to river-derived nutrients and sediments. The region is characterized by weak winds, moderate tides, and almost absent Coriolis forcing. Existing knowledge about river plume behavior in tropical environments is limited. The aim of this paper is to investigate the influence of the subtle physical forcing on the dynamics of the Berau river plume. A three-dimensional model (ECOMSED) was calibrated with observational data. The model was forced by freshwater input from the Berau river distributaries, tides at the open boundaries, and measured hourly wind. The model reproduces the freshwater dynamics on the shelf adequately and highlights that the river plume spreads symmetrically for river forcing only. Tides cause vertical mixing and suppress the cross-shelf spreading of the river plume. However, the spreading of the river plume over the shelf is mainly controlled by the weak monsoonal winds, resulting in a seasonal development. During the Southeast Monsoon, the southerly winds push the plume northeastward and cause a stratified water column in the northern part of the continental shelf. Northerly winds during the Northwest Monsoon disperse the plume to the south, promoting a vertically well-mixed water column. The results can be used to predict the possible impact of land-use changes in the steadily developing Berau region on coral reef health.

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Section: Introductionmentioning

confidence: 98%

Wind forcing controls on river plume spreading on a tropical continental shelf

2015

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“…Besides some restrictions on the aplication of HCT in marine environments, we used the approach developed by Cudaback & Jay (1996) in the Columbia River (OR, EUA). Fontes et al (2008) followed the same method on the inner Amazon Shelf, near the river mouth. According to the HCT, the river discharge may be subject to changes on its dynamical state, where the dynamic condition state turns from super-critical to sub-critical when it passes trough an internal hydraulic jump.…”

Section: Approximation Of the Hydraulic Control Theorymentioning

confidence: 99%

“…Using the same modeling dynamics described in Fontes et al (2008), we considered the evaluation of cohesive sediments from the river discharge into the AS and ASD. The environmental dynamic conditions and charges of sediments represent climatological conditions of the AS, which are in Table 1 The evolution of cohesive sediment concentrations over the ASD is in Fig.…”

Section: The Influence Of Tides On Sediment Dynamicsmentioning

confidence: 99%

“…Winds and waves are moderated in this region and do not have relative importance on the local dynamics, although it may be relevant on ressuspension and sediment transport during extreme events. Former studies as (Beardsley et al, 1995;Fontes et al, 2008;Gabioux et al, 2005;Geyer et al, 1996), among others, have measured or modeled the tidal amplification due to supression of the bottom stress, imposed by fluid mud layers. The bathymetry and site locations in the AS are in Fig.…”

Section: Characteristics Of the Amazon Shelf Regionmentioning

confidence: 99%

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Hydrodynamic Influences on Fluid Mud Distribution in the Amazon Subaqueous Delta

Fontes¹,

Ciotti²,

Castro³

2011

Sediment Transport in Aquatic Environments

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“…The use of oil dispersant to prevent floating oil from reaching the shore caused even more damage to reef communities in the Gulf of Mexico, as the widely used dispersant (Corexit R ) causes oil to sink, suffocating benthic communities, as well as decreased coral larvae settlement and survival (GoodbodyGringley et al, 2013). Previous time-series studies performed in the GARS demonstrate current velocities below sea surface of ∼0.3-1.5 m.s −1 close to the areas of oil exploration, indicating rapid spread may occur in the event of an oil spill (Geyer et al, 1991;Fontes et al, 2008).…”

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confidence: 99%

Perspectives on the Great Amazon Reef: Extension, Biodiversity, and Threats

et al. 2018

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Here we provide a broad overview of the Great Amazon Reef System (GARS) based on the first-ever video surveys of the region. This footage supports four major hypotheses: (1) the GARS area may be six times larger than previously suggested (up to 56,000 km 2 ); (2) the GARS may extend deeper than previously suggested (up to 220 m); (3) the GARS is composed of a greater complexity and diversity of habitats than previously recognized (e.g., reef platforms, reef walls, rhodolith beds, and sponge bottoms); and (4) the GARS represents a useful system to test whether a deep corridor connects the Caribbean Sea to the Southwest Atlantic Ocean. We also call attention to the urgent need to adopt precautionary conservation measures to protect the region in the face of increasing threats from extractive oil and gas practices. With less than 5% of the potential area of the GARS surveyed so far, more research will be required to inform a systematic conservation planning approach and determine how best to establish a network of marine protected areas. Such planning will be required to reconcile extractive activities with effective biodiversity conservation in the GARS.

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Numerical study of circulation on the inner Amazon Shelf

Cited by 29 publications

References 21 publications

Wind forcing controls on river plume spreading on a tropical continental shelf

Wind forcing controls on river plume spreading on a tropical continental shelf

Hydrodynamic Influences on Fluid Mud Distribution in the Amazon Subaqueous Delta

Perspectives on the Great Amazon Reef: Extension, Biodiversity, and Threats

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