Chapter 14 Sediment Transport Processes in Estuaries

Dyer, K.R.

doi:10.1016/s0070-4571(05)80034-2

Cited by 137 publications

(118 citation statements)

References 37 publications

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“…The general increase in SSC with distance upstream (Table 1) and colocation of the freshwater-saltwater interface suggest an ETM region at or just downstream of section C. ETMs often form at or near the head of salinity intrusion [Dyer, 1995], and section C during low flow captured the freshwater-saltwater interface. The finegrained bed sediment at A and B suggests significant sediment trapping in those locations, but the mud cap imported during low flow did not extend past the upper limit of Cu Lao Dung.…”

Section: Geomorphic Responsementioning

confidence: 99%

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

et al. 2015

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A better understanding of flow and sediment dynamics in the lowermost portions of large‐tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended‐sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high‐seasonal and low‐seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s−1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s−1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr−1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high‐flow sediment export. Exchange‐flow and tidal processes, including local resuspension, were principally responsible for the low‐flow import. The resulting bed‐sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid‐channel islands.

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Section: Geomorphic Responsementioning

confidence: 99%

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

et al. 2015

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“…Neste caso, as correntes residuais podem ser provenientes de dois tipos principais de circulação (Dyer, 1995), sendo eles:…”

Section: Introductionunclassified

“…O importante no processo é observar as velocidades residuais da corrente, pois estas condicionam a direção preferencial do transporte dos sedimentos. Geralmente, na superfície são em direção ao oceano, enquanto que as velocidades residuais no fundo ocorrem em direção ao continente (Dyer, 1995);…”

Section: Introductionunclassified

“…Caso não ocorra contribuição fluvial, será a assimetria gerada entre os estágios de enchente e vazante da maré que dará o sentido predominante do fluxo (Dyer, 1995). Em caso da descarga fluvial sobrepujar o efeito da maré, não permitindo correntes de enchente, o rio bombeará água para fora do estuário.…”

Section: Introductionunclassified

“…Quando a convergência e a fricção são iguais, a altura de maré é constante ao longo do estuário, sendo denominada de sincrônica. Estuários hipossincrônicos são aqueles nos quais o efeito da fricção domina, fazendo com que a altura da maré diminua ao longo do estuário (Nichols & Biggs, 1985;Dyer, 1995;Dyer, 1997). Associado a amplificação ou amortecimento da onda de maré pode ocorrer a deformação da onda, gerando tempos de enchente e vazante desiguais.…”

Section: Introductionunclassified

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Modelagem numérica da dinâmica do sistema estuarino Caravelas - Peruíbe, BA

Santos¹

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Structure of the turbidity field in the Guadalquivir estuary: Analysis of observations and a box model approach

et al. 2014

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A study is presented on the transport of suspended particulate matter (SPM) in the Guadalquivir estuary during low river flow conditions. Observations show that tidally induced SPM exceeds that associated with catchment-derived inputs. The main mechanisms that contribute to longitudinal transport are identified and quantified by analyzing the tidally averaged and depthintegrated SPM flux decomposition over time and space. The net transport is generally directed upstream, although differences in the direction between spring and neap tides are identified. The transport is largely controlled by the mean advection, the tidal pumping associated with the covariance between SPM concentration and current, and the tidal Stokes transport. The convergence of the transport associated to these mechanisms alone explains the presence of primary and secondary estuarine turbidity maxima. The tidal reflection at the upstream dam appears to play a significant role in their generation, as evidenced by the convergence zones of the M4 and M2 induced tidal pumping transports. The spatial structure of the transport motivates the development of a box model that describes the concentration of SPM and its exchange between different stretches along the estuary at subtidal time scales. The model is fed by the net SPM transport obtained from observations. Analysis of the morphodynamical state of the estuary using the box model indicates that erosion is dominant in the stretches close to the estuary mouth and that this sediment is transported upstream and deposited in the middle part of the estuary. This process is more influential during spring tides than during neap tides.

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Chapter 14 Sediment Transport Processes in Estuaries

Cited by 137 publications

References 37 publications

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

Modelagem numérica da dinâmica do sistema estuarino Caravelas - Peruíbe, BA

Structure of the turbidity field in the Guadalquivir estuary: Analysis of observations and a box model approach

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