Tide-driven controls on maximum near-bed floc size in a tidal estuary

Razaz, Mahdi; Kawanisi, Kiyosi; Nistor, Ioan

doi:10.1016/j.jher.2014.04.001

Cited by 6 publications

(10 citation statements)

References 20 publications

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“…The Otagawa estuary is composed of a shallow and tide-controlled delta with several channels. The maximal tidal compartment range reaches up to around 13 km from the river mouth (Razaz et al, 2015). The Ota river divides into two main branches nearly 9 km upstream from the river mouth.…”

Section: Study Areamentioning

confidence: 99%

“…The flow pattern varies considerably with both the tidal phase and the amount of runoff flowing through the gates. Razaz et al (2015) pointed out that tidal straining and bathymetry are the main sources of flocculation in the Otagawa floodway. Kawanisi et al (2008a) discussed the effects of river discharge, tidal range, and wind on the transport of sediment.…”

Section: Study Areamentioning

confidence: 99%

“…A long-term discharge monitoring campaign was conducted using the fluvial acoustic tomography (FAT) system, showing that around 20% of the total Ota River discharge flowed into the floodway on normal days and that it received up to 50% of the total runoff during flood events (Kawanisi et al, 2010). Furthermore, it was reported that the maximum tidal current velocities during flood and ebb were around 0.65 m/s and 0.5 m/s, respectively, and during the spring tide the peak tidal range reached 4 m at the river mouth (Razaz et al, 2015). In general, due to the limited runoff under normal conditions and mesotidal inflow from Hiroshima Bay, the estuarine circulation in the Otagawa floodway is moderate.…”

Section: Study Areamentioning

confidence: 99%

See 2 more Smart Citations

Suspended particulate matter concentration in response to tidal hydrodynamics in a long mesotidal floodway

Xiao

Kawanisi

Sawaf

2020

Estuarine, Coastal and Shelf Science

Self Cite

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

See 1 more Smart Citation

Suspended particulate matter concentration in response to tidal hydrodynamics in a long mesotidal floodway

Xiao

Kawanisi

Sawaf

2020

Estuarine, Coastal and Shelf Science

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“…Desta forma, as medidas detalhadas de campos de velocidade e da corrente em rios são essenciais para a análise dos efeitos das marés nos processos dispersivos em corpos d´água estuarinos. Por outro lado, será também mostrado e discutido que tais medições são complexas e difíceis de executar em campo por causa da característica transiente dos escoamentos nesses ambientes (KAWANISI, 2004;RAZAZ et al, 2015). Isto é, compreender como a estrutura hidrodinâmica se relaciona com CL e é influenciada por meandro em transformação geomorfológica intensa neste trecho da bacia do Rio Araguari (SANTOS et al, 2017).…”

Section: Introductionunclassified

Circulação secundária atípica em meandro fluviomarinho como parâmetro hidrodinâmico em ecossistema aquático amazônico

Santos

Cunha

2021

RICA

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A circulação lateral (CL) em curvaturas de rios é influenciada pela morfologia dos canais, sendo relevante em processos de mistura que interferem na variação da qualidade da água. O objetivo desta pesquisa é avaliar CL a partir do escoamento hidrodinâmico, curvatura e geometria de um rio fluviomarinho amazônico. O escoamento foi quantificado em uma seção transversal do Rio Araguari-Amapá/Brasil cujas características geométricas são consideradas ideais para testar CL em trechos curvos (raio de curvatura ≈5900 m). As medidas ocorreram trimestralmente durante ciclos de marés semidiunos (12,5h), em Junho, Setembro e Dezembro/2013 e Março/2014 e 2015, utilizando um perfilador de corrente acústico (ADCP). Este trecho apresenta perturbação hidrodinâmica de um afluente próximo a montante de uma expansão lateral do canal, que varia de 850 para 1750 m e, posteriormente, de 1750 para 2900 m. Os perfis hidrodinâmico e geométrico foram processados nos softwares Matlab e Tecplot, permitindo avaliar e comparar o padrão das linhas de corrente do escoamento formador da CL com informações similares da literatura. Os resultados indicaram ausência de um padrão helicoidal típico. Assim, na maré vazante as linhas de corrente fluem da margem externa para a interna em descendente da superfície para o fundo. Na maré enchente, ocorreu o oposto, com linhas de corrente fluindo da margem interna para a externa em ascendência. Testes estatísticos de hipótese mostraram que fatores físicos além da curvatura (rio a montante, expansão geométrica, fases das marés e sazonalidade) restringiram a formação do padrão helicoidal esperado na seção de estudo. Concluímos que apesar destes fatores a intensidade do fluxo secundário foi mais influenciada pela fase da maré, onde o menor valor de Vy((Transversal)/Vx(Longitudinal) ocorreu na fase vazante (≈ 0,091) e o maior na fase enchente (≈ 0,169). Assim, CL variou no intervalo [≈10% ≤ CL ≤ ≈17%], representando uma considerável forçante física de mistura no escoamento, mesmo em rios com curvaturas relativamente baixas como a apresentada no Rio Araguari no presente estudo.

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“…Low shear enhances flocculation, and the high settling velocity of larger flocs results in reduced SSC; at high shear, flocs disintegrate and their settling velocity decreases, as a consequence of which the resulting small flocs remain in suspension and SSC increases (Burban et al 1989;Dyer and Manning 1999;Safak et al 2013;Razaz et al 2015). In other words, floc formation and destruction are controlled mainly by turbulence and SSC (Shi 2010;Razaz et al 2015). Dyer and Manning (1999) suggested that the effect of SSC appears to be greater than that of turbulent shear, whereas Wang et al (2013) indicated that floc size appears to be controlled by turbulent shear more than by any other parameter.…”

Section: Introductionmentioning

confidence: 99%

On the variability of near-bed floc size due to complex interactions between turbulence, SSC, settling velocity, effective density and the fractal dimension of flocs

Yang

Wang

et al. 2016

Geo-Mar Lett

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Interactions between turbulence, suspended sediment concentration (SSC), settling velocity, effective density, fractal dimension, and floc size were studied on the tide-dominated, muddy coastal shelf of the southwestern Yellow Sea, China. The measurements were carried out in July 2013 at two sites located in water depths of 21.2 and 22.1 m. Negative correlations were observed between shear rate, SSC, effective density, and mean floc size, which supports the results of previous numerical, experimental, and field studies. A significant positive correlation was observed between near-bed SSC and shear rate, an indication that SSC variations are controlled by turbulence and re-suspension. In addition, significant linear relationships were found between settling velocity and other parameters (floc size, turbulence, SSC, effective density, and fractal dimension) at the two sites, indicating that the controlling factors on settling velocity are spatially variable. Principal component analysis was applied to determine the relative importance of turbulence, flocculation ability, and SSC as controls on floc size in situ. The relative contributions of turbulence, flocculation ability, and SSC to floc size (at both sites) were~33.0%, 30.3%, and 29.7%, respectively, this being a new field-based quantitative analysis of the controls on floc size. The findings demonstrate that, in nature, flocculation ability affects floc size to the same degree as turbulence and SSC. Therefore, predictions of floc size in coastal marine environments require constraints not only on turbulence and SSC, but also on flocculation ability.

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Tide-driven controls on maximum near-bed floc size in a tidal estuary

Cited by 6 publications

References 20 publications

Suspended particulate matter concentration in response to tidal hydrodynamics in a long mesotidal floodway

Suspended particulate matter concentration in response to tidal hydrodynamics in a long mesotidal floodway

Circulação secundária atípica em meandro fluviomarinho como parâmetro hidrodinâmico em ecossistema aquático amazônico

On the variability of near-bed floc size due to complex interactions between turbulence, SSC, settling velocity, effective density and the fractal dimension of flocs

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