Estuaries

Nichols, Maynard M.; Biggs, Robert B.

doi:10.1007/978-1-4612-5078-4_2

Cited by 141 publications

(85 citation statements)

References 87 publications

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“…Segundo Nichols & Biggs (1985), as marés astronômicas sofrem processos de distorção ao entrarem em sistemas restritos devido aos efeitos de fricção com o fundo e constrição das margens, podendo haver diminuição (hiposíncrono), manutenção (síncrono) ou amplificação (hipersíncrono) da altura de marés. Em estuários do tipo frente deltaica (e.g.…”

Section: Discussionunclassified

Oscilação do nível de água e a co-oscilação da maré astronômica no baixo estuário do rio Paraíba do Sul, RJ

Nicolite¹,

Truccolo²,

Schettini³

et al. 2009

Rev. Bras. Geof.

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ABSTRACT. The water level in the lower Paraíba do Sul river estuary was assessed in order to evaluate the effects of the astronomical tide co-oscillation, river discharge and meteorological events. Water level data was recorded hourly from October 2000 until February 2003 at a gauge station nearby the estuarine inlet. The water level is controlled mainly by the astronomical tide co-oscillation during periods of low river discharge, and eventually by meteorological tides. Even during periods of higher river discharge the water level is controlled by astronomical co-oscillation, although during low tide phase the river discharge effects are observable. During periods of extreme high discharge the low frequency water level is mainly driven by the river inflow. The tidal wave was mostly symmetrical during the low river discharge periods, and asymmetries were observed during meteorological events, with shorter flood and longer ebbs. Although, such effects were not corroborated by astronomical tidal constituents M 2 and M 4 relationship, which suggests ebb dominance. Stronger distortions were observed during high discharge periods, with tide attenuation either at neap as in spring tide periods. During these periods the asymmetries were corroborated by M 2 and M 4 relationship.Keywords: tidal asymmetry, meteorological tides, river discharge. RESUMO.A variabilidade do nível daágua no baixo estuário do rio Paraíba do Sul foi estudada para avaliar os efeitos da co-oscilação da maré astronômica, descarga fluvial e de eventos meteorológicos. Dados de nível daágua foram registrados em intervalos horários para o período entre outubro de 2000 até fevereiro de 2003 em uma estação localizada próximoà desembocadura do estuário. Foi observado que durante os eventos de descarga fluvial baixa os níveis deágua do estuário oscilam principalmente em função da co-oscilação da maré astronômica e eventualmente por marés meteorológicas. Durante períodos de descarga fluvial alta o nível daágua de preamar no baixo estuárioé dominado pela co-oscilação, enquanto que nas baixa-maresé influenciado pela descarga fluvial. Em períodos de descarga fluvial muito alta o estuário passa a receber a influência tanto da descarga fluvial quanto da maré astronômica nas oscilações do nível. Em períodos de baixa descarga quase não houve modificação na onda de maré, sendo observada pequena assimetria no sentido de vazante. Ainda em baixa descarga, eventos de maré meteorológica produzem distorções e assimetrias, com o tempo de subida menor que o de descida, gerando correntes mais fortes no sentido de enchente. Contudo, isto não pôde ser confirmado com a relação de fase entre M 2 e M 4 , que sugeriu domínio de vazante. A descarga fluvial alta causou fortes distorções na onda de maré em períodos de quadratura e uma atenuação considerável nas amplitudes tanto de sizígia como de quadratura, com assimetrias no sentido de vazante corroboradas pela relação de fase entre M 2 e M 4 .Palavras-chave: assimetria de maré, marés meteorológicas, descarga fluvial.

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Section: Discussionunclassified

Oscilação do nível de água e a co-oscilação da maré astronômica no baixo estuário do rio Paraíba do Sul, RJ

Nicolite¹,

Truccolo²,

Schettini³

et al. 2009

Rev. Bras. Geof.

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“…Larger particles settle out first upriver, in conformity with Stoke's Law, leaving the smaller particles suspended. Under appropriate conditions of concentration and salinity, floc formation may favor the deposition of smaller clay-sized particles farther downriver that would otherwise remain in suspension (Dyer, 1995;Nichols & Biggs, 1985).…”

Section: Soil Characteristicsmentioning

confidence: 99%

“…For example, the long-term average at nearby Sweet Hall Marsh is 0.5, but the average in 1999 was 2.8 with a range of 0.0 to 15.9 (Neubauer et al, 2002). Estuaries generally have a turbidity maximum where suspended sediment concentrations are higher than they are either landward or seaward, and it is located near the head of the salt intrusion (Nichols & Biggs, 1985;Dyer, 1995). Zhuraleva and Morozova (1999) found that the turbidity maximum usually occurred at a salinity of approximately 2 in the Lower Dnieper River, Russia.…”

Section: Salt Water Intrusionmentioning

confidence: 99%

“…Zhuraleva and Morozova (1999) found that the turbidity maximum usually occurred at a salinity of approximately 2 in the Lower Dnieper River, Russia. The turbidity maximum may shift seasonally as a result of freshwater discharge (Fettweis, Sas, & Monbaliu, 1998), and well-developed turbidity maxima tend to be established during periods of low river discharge (Nichols & Biggs, 1985). If the freshwater/salt water interface was located near Gleason during the study period, the turbidity maximum would have provided large amounts of suspended sediment that was not available at the Walkerton site located 19 km upriver where the fluvial influence was greater.…”

Section: Salt Water Intrusionmentioning

confidence: 99%

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Control of sediment deposition rates in two mid-Atlantic Coast tidal freshwater wetlands

Darke

Megonigal

2003

Estuarine, Coastal and Shelf Science

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“…9) indicate that during the dry season thickest laminae development is coincident with the turbidity maximum position. Estuarine circulation models (Nichols and Biggs, 1985;Hart, 1995) suggest that this might be where these phenomena (highest number of laminae and greatest thickness) are most likely to occur. During the dry season upstream of this region, fluvial processes start to dominate transport and downstream sediments are generally transported upstream toward the turbidity maximum.…”

Section: Intertidal Sedimentation Foraminifera Assemblages and Progmentioning

confidence: 99%

Seasonal sediment transport and deposition in the Rajang River delta, Sarawak, East Malaysia

Staub

Among²,

Gastaldo

2000

Sedimentary Geology

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The Holocene Rajang River delta plain, which covers an area of 6500 km 2 , has developed in a tropical, ever-wet climatic setting. Peat deposits, up to 15 m thick, occur in this delta plain. The tributary system to the delta is about 50,000 km 2 in area. Elevations exceed 2000 m in the drainage basin and hill slopes are steep. Rainfall in the region exceeds 370 cm/year, with highest rainfall levels or the "wet" season being coincident with the December-March monsoon. The monthly drainage-basin discharge is calculated to average about 3600 m 3 /s, and the discharge normally ranges from 1000 to 6000 m 3 /s. Spring tides in coastal areas range from 2.9 to 5.8 m. Tide data indicate that the tides are semidiurnal with a noticeable diurnal inequality. Vibracores recovered from bar forms in tidally influenced distributary channels contain laminated silts and sand-silt couplets that show evidence of rhythmic heterolithic stratification. Grain-size data indicate that these preserved delta plain siliciclastic sediments are the result of estuarine depositional processes that occur during intervals of reduced rainfall or the "dry" season (April-November). The number of laminae preserved per neap-spring cycle is the highest (ഡ18-20), and the average thickness is the greatest in the middle part of the delta plain. Distributary channels in this region normally contain low-salinity brackish water to freshwater. Vibracores recovered from delta front and prodelta sediments show evidence of heterolithic stratification, but rhythmicity is absent. Grain-size data indicate that preserved delta front and prodelta sediments are implaced by "wet" season processes (December-March) when fluvial flux and delta-plain erosion are at their maxima. Individual silt laminae and/or silt and sand interbeds are sometimes many centimeters thick, but average about 1 cm. These silt laminae and silt and sand interbeds or varves represent annual sedimentation events. These varves demonstrate that about 24 million MT of sediment produced by the drainage basin is deposited in the delta front and prodelta region annually. ᭧

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Estuaries

Cited by 141 publications

References 87 publications

Oscilação do nível de água e a co-oscilação da maré astronômica no baixo estuário do rio Paraíba do Sul, RJ

Oscilação do nível de água e a co-oscilação da maré astronômica no baixo estuário do rio Paraíba do Sul, RJ

Control of sediment deposition rates in two mid-Atlantic Coast tidal freshwater wetlands

Seasonal sediment transport and deposition in the Rajang River delta, Sarawak, East Malaysia

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