Lateral Circulation and Associated Sediment Transport in a Convergent Estuary

Chen, Lianghong; Zhang, Heng; Zhu, Lei; Cheng, Weicong

doi:10.1029/2019jc015926

Cited by 17 publications

(8 citation statements)

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“…The Coriolis force was small but always westward, and therefore enhanced the westward deflection of the seaward flow. The lateral circulation due to lateral baroclinic pressure gradient and Coriolis force deflection of the longitudinal flow had a significant influence on the lateral sediment entrapment (Chen et al, 2020;Huijts et al, 2006). For the sediment transport at the D1 transect, the SSC change rate (   C t ) was low and was mainly balanced by settling (Er) and erosion (Dp) (Figure 17e).…”

Section: Mechanisms Of Wave Effects On Lateral Entrapmentmentioning

confidence: 99%

Wave Effects on Sediment Transport and Entrapment in a Channel‐Shoal Estuary: The Pearl River Estuary in the Dry Winter Season

et al. 2021

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Sediment dynamics have substantial effects on the morphology of estuaries and deltas (Wright & Coleman, 1973) and have an enormous influence on estuarine and marine environments (Turner & Millward, 2002). Sediment transport and distribution in estuaries are heavily affected by river's discharge of freshwater and sediment, and by tides, winds, waves, and bathymetry (Dyer, 1997).The supply of river sediments to many estuarine systems has decreased over the past 50 years, especially in Africa and Asia, due to upstream damming and sand extraction (Syvitski et al., 2005(Syvitski et al., , 2009. This reduction in sediment input alters the morphology of estuaries, deltas, and coasts, and leads to depletion of the Abstract Sediment dynamics have great effects on the morphology of estuaries and deltas. As riverine sediment input has decreased in many estuaries in recent years, the removal and dispersion of sediments by currents and waves inside estuaries has assumed a more dominant role; however, the overall effects of waves are less well understood. In this study, we used the Coupled Ocean Atmosphere Wave Sediment Transport system to model the effects of waves on sediment transport in China's Pearl River Estuary. The results indicate that the presence of waves increased the landward current and sediment transport at the bottom of the channel and the seaward fluxes of water and sediment at the West Shoal, which is the main shallow area that accepts riverine sediment. Relative to the case without waves, the effects of waves increased the estuary's total sediment export by 45% to 9.14 megatons in one typical year, which even exceeded the annual riverine load in the year. The dry winter season shows the highest wave effects on sediment budget, and the sediment export was increased by 86% to 2.59 megatons with waves when compared with that without waves. This increase export was mainly concentrated at the surface near the western shore. Moreover, the waves increased lateral sediment entrapment in the Southwest Shoal, which explains the local geomorphologic evolution in recent decades. This study is of implication for the study on sediment exchange between shoal and channel in estuaries and on the fates of riverine sediment from source to sink.Plain Language Summary Waves have significant impacts on estuarine mixing, circulation, and sediment dynamics, which may affect the morphology of estuaries and deltas, water quality, and the overall estuarine ecosystems. Despite these substantial effects, the mechanisms of wave effects affecting estuarine circulation and lateral sediment entrapment in a channel-shoal estuary have not received adequate attention. Here, we use a validated coupled ocean model system to investigate the wave effects on longitudinal/lateral circulation and sediment transport/entrapment in a channel-shoal estuary. We note that the waves influence the surface and bottom stress, vertical mixing, and sediment resuspension. And in turn, these lead to the enhancement of tidal asymmetries and seaward sediment flux. M...

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Section: Mechanisms Of Wave Effects On Lateral Entrapmentmentioning

confidence: 99%

Wave Effects on Sediment Transport and Entrapment in a Channel‐Shoal Estuary: The Pearl River Estuary in the Dry Winter Season

et al. 2021

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“…As revealed by Lerczak and Geyer (2004) and other researchers (Chen et al, 2020b), lateral processes play important roles in the generation of the longitudinal estuarine circulation. The lateral circulation can modify the longitudinal estuarine circulation by the lateral redistribution of the longitudinal current in a direct way (Lerczak and Geyer, 2004), and change the longitudinal pressure gradient force and the friction in an indirect way.…”

Section: Introductionmentioning

confidence: 82%

“…As mentioned above, the hydrodynamics in the HE experiences distinct seasonal variation. The estuarine circulation during the wet season has been extensively studied before (Chen et al, 2020a;Chen et al, 2020b). Here we choose the dry season to investigate the changes in the estuarine circulation caused by topographic changes in different years.…”

Section: Numerical Model Setting Up and Validationmentioning

confidence: 99%

“…1b): at River 2 by specifying real-time water level data from the MD1 model from 00:00 on March 1, 2010, to 23:00 on March 31, 2010, with a time interval of 1 hour; At River 1 by specifying a constant river discharge of 100 ms -2 . The choice of this constant value was based on the previous simulation experiences (Chen et al, 2020a;Chen et al, 2020b). The salinities at the river inflow boundaries were set to be 0 psu.…”

Section: Numerical Model Setting Up and Validationmentioning

confidence: 99%

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Responses of estuarine circulation to the morphological evolution in a convergent, microtidal estuary

Zhang

Hong

Zhu

et al. 2021

Preprint

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Abstract. The Huangmaohai Estuary (HE) is a funnel-shaped microtidal estuary in the west of the Pearl River Delta (PRD) in southern China. Since China's reform and opening up in 1978, extensive human activities have occurred and greatly changed the estuary's topography, and modified its hydrodynamics. In this study, we examined the morphological evolution by analyzing remote sensing data with ArcGIS tools and studied the responses of hydrodynamics to the changes in topography from 1977 to 2010 by using the Delft3d model. We took the changes in estuarine circulation during neap tides in dry seasons as an example. The results show that human reclamation caused a narrowing of the estuary, and channel dredging deepened the estuary. These human activities changed both the longitudinal and lateral estuarine circulations. The longitudinal circulation was observed to increase with the deepening and narrowing of the estuary. The lateral circulation experienced changes in both the magnitude and pattern. The momentum balance analysis shows that when the depth and width changed simultaneously, the longitudinal estuarine circulation was modulated by both the channel deepening and width reduction, in which the friction, pressure gradient force, and advection terms were altered. The analysis of the longitudinal vortex dynamics indicates that the changes in the vertical shear of the longitudinal flow, lateral salinity gradient, and vertical mixing were responsible for the change in the lateral circulation. The changes in water depth are the dominant factor affecting lateral circulation intensity. This study has implications for sediment transport and morphological evolution in estuaries heavily impacted by human interventions.

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“…Numerous studies about siltation issues have been conducted, focusing on (1) mechanisms for longitudinal convergence of sediment, including ETM dynamics (Burchard et al., 2018); (2) lateral circulation and consequently induced sediment trapping (Chen et al., 2020; Yang et al., 2014); (3) vertical processes in sediment dynamics, including settling and resuspension (Dankers & Winterwerp, 2007; Ge et al., 2018). This research provides some new information about sediment transport, which is important to deposition issues in a highly silted channel‐shoal system.…”

Section: Discussionmentioning

confidence: 99%

Study of Sediment Transport in a Tidal Channel‐Shoal System: Lateral Effects and Slack‐Water Dynamics

Zhou

Maren

et al. 2021

JGR Oceans

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Sediment transport in estuaries directly influences the bed level which in turn impacts the navigability of shipping channels. Sediment dynamics also influence estuarine ecology, for instance through water clarity (and therefore primary production, providing the base of the food chain) and habitat suitability (especially on the intertidal areas)-see Wood (1997). In many systems worldwide, estuarine sediment dynamics are increasingly modified by changes in river and sediment discharges (

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Lateral Circulation and Associated Sediment Transport in a Convergent Estuary

Cited by 17 publications

References 36 publications

Wave Effects on Sediment Transport and Entrapment in a Channel‐Shoal Estuary: The Pearl River Estuary in the Dry Winter Season

Wave Effects on Sediment Transport and Entrapment in a Channel‐Shoal Estuary: The Pearl River Estuary in the Dry Winter Season

Responses of estuarine circulation to the morphological evolution in a convergent, microtidal estuary

Study of Sediment Transport in a Tidal Channel‐Shoal System: Lateral Effects and Slack‐Water Dynamics

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