The influence of human activities on morphodynamics and alteration of sediment source and sink in the Changjiang Estuary

Zhu, Lei; He, Qing; Shen, Jian; Ya, Wang

doi:10.1016/j.geomorph.2016.07.025

Cited by 79 publications

(51 citation statements)

References 47 publications

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“…Here we implement a numerical model based on two bathymetries surveyed in 1997 and in 2010. Although similar studies have been carried out in parts of the YRE (Jiang et al, 2012;Song & Wang, 2013;Zhu et al, 2016), this study is one of the few that focuses on the entire system and explores possible feedbacks between hydrodynamics and morphology. In tidal deltas, hydrodynamic variables including tidal prism and tidal range increase seaward as the estuary width increases.…”

Section: Discussionmentioning

confidence: 99%

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

et al. 2018

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Tidal deltas are fragile systems whose morphology can be easily impacted by variations in water and sediment fluxes caused by natural and human processes. Here we explore the relation between tidal prism and sediment dynamics in tidal deltas using the recent evolution of the Yangtze River estuary, China, as an example. Using the numerical model Delft3D, we examine how changes in delta morphology can trigger variations in tidal signal, suspended and bed load transport, and how these could ultimately cause additional morphological changes. Our results show that a positive feedback between sediment deposition and tidal prism dominates the morphodynamic evolution of the delta. Accretion of the shoals in the delta front increases the dissipation of tides and decreases the tidal prism leading to weaker tidal flows. This reduction in tidal currents lowers the sediment flushing capacity of the system, promoting deposition on the shoals and tidal dissipation. This positive feedback potentially traps more sediment in the delta topset and possibly offsets the decrease in sediment load triggered by the construction of upstream dams, often present in tidal deltas.

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Section: Discussionmentioning

confidence: 99%

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

et al. 2018

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“…A major intervention was engineering work in the North Passage (NP), involving the construction of a nearly 50 km-long double training wall with groins (see Figure 1). The jetties and groins in the NP are so large that they may induce severe erosion in the mouth of the NP and in the region to the east of Hengsha flat (Zhu et al, 2016). The jetties partially block regional horizontal circulation (Zhu et al, 2016), possibly leading to sediment deposition and accretion over the surrounding flats.…”

Section: Introductionmentioning

confidence: 99%

“…The jetties and groins in the NP are so large that they may induce severe erosion in the mouth of the NP and in the region to the east of Hengsha flat (Zhu et al, 2016). The jetties partially block regional horizontal circulation (Zhu et al, 2016), possibly leading to sediment deposition and accretion over the surrounding flats. In addition, intense dredging and dumping activities take place in the NP.…”

Section: Introductionmentioning

confidence: 99%

Decadal morphological evolution of the mouth zone of the Yangtze Estuary in response to human interventions

Zhu

Guo

Maren

et al. 2019

Earth Surf Processes Landf

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The morphology of the Yangtze Estuary has changed substantially at decadal time scales in response to natural processes, local human interference and reduced sediment supply. Due to its high sediment load, the morphodynamic response time of the estuary is short, providing a valuable semi‐natural system to evaluate large‐scale estuarine morphodynamic responses to interference. Previous studies primarily addressed local morphologic changes within the estuary, but since an overall sediment balance is missing, it remains unclear whether the estuary as a whole has shifted from sedimentation to erosion in response to reduced riverine sediment supply (e.g. resulting from construction of the Three Gorges Dam). In this paper we examine the morphological changes of two large shoals in the mouth zone (i.e. the Hengsha flat and the Jiuduan shoal) using bathymetric data collected between 1953 and 2016 and a series of satellite images. We observe that the two shoals accreted at different rates before 2010 but reverted to erosion thereafter. Human activities such as dredging and dumping contribute to erosion, masking the impacts of sediment source reduction. The effects of local human intervention (such as the construction of a navigation channel) are instantaneous and are likely to have already resulted in new dynamic equilibrium conditions. The morphodynamic response time of the mouth zone to riverine sediment decrease is further suggested to be >30 years (starting from the mid‐1980s). Accounting for the different adaptation time scales of various human activities is essential when interpreting morphodynamic changes in large‐scale estuaries and deltas. © 2019 John Wiley & Sons, Ltd.

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“…In coastal environments, the waves generate coastal currents that interact with incident waves and lead to the sediment transportation and the process is favored when the angle between the waves and the coastal line is significant [13][14][15][16]. As a response to coastal hydrodynamics, the alternation of sedimentation and erosion processes in the estuary can generate net sedimentary balances through a tide cycle [17,18].The installation of hydraulic reservoirs in upstream areas affects the hydrodynamic equilibrium and sedimentary balances downstream, due to the flood water regulation and the decrease of the solid sediments supply [19][20][21][22][23][24][25]. Blott) [26] concluded that the morphodynamic evolution of Mersey estuary in England through a period of 150 years was mainly controlled by engineering and rehabilitation works, such as the construction of training walls and dredging.…”

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confidence: 99%

“…Blott) [26] concluded that the morphodynamic evolution of Mersey estuary in England through a period of 150 years was mainly controlled by engineering and rehabilitation works, such as the construction of training walls and dredging. Besides, the importance of other factors, notably sea level change, tide amplitude, wave current, and supply of fresh water was relatively reduced [26].The perturbation of estuarine hydrodynamics is permanently regulated by morphologic transformations through sedimentation and erosion processes mobilized to re-establish the hydrodynamic equilibrium [21,22,27]. The morphodynamic change concerns the estuary outlet, the main channel, and the intertidal plains [19,20,28].…”

mentioning

confidence: 99%

Impact of Anthropogenic Facilities on the Morphodynamic Evolution of an Estuarine System: The Case of Oum Er-Rbia Estuary (Azemmour, Morocco)

Jakani

Ettazarini

Rhinane

et al. 2019

JMSE

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The Oum Er-Rbia estuary is located on the Atlantic littoral of Morocco. It undergoes severe clogging due to the sand deposition in its outlet. The current study examined the indicators of the morphodynamic evolution in the littoral system including the Oum Er-Rbia estuary and the neighboring beaches over 1970-2017. The methodology adopted was based on the analysis and the interpretation of aerial photographs and Google Earth images under a GIS environment and field work. The morphodynamic evolution was discussed by taking into account the evolution of hydraulic facilities installed in the watershed area, especially the construction of dams, as well as the dredging works in the Oum Er-Rbia estuary. The results highlight the morphologic evolution estimated in terms of surface units observed in the estuary and the neighboring beaches. The evolution of the littoral system was mainly influenced by the closest dam location and by the dredging works, in addition to the regulation of the river flow by the installation of hydraulic facilities upstream.anthropogenic factors such as hydraulic facilities, engineering works of protection and rehabilitation, dredging, etc. [6][7][8][9][10].The bathymetry and the morphology of an intertidal plain and transversal section of a shallow bottom estuary cause a tide asymmetry that affects the flow duration, compared to the ebb time, and the celerity of the tide current [1,2,[10][11][12]. In coastal environments, the waves generate coastal currents that interact with incident waves and lead to the sediment transportation and the process is favored when the angle between the waves and the coastal line is significant [13][14][15][16]. As a response to coastal hydrodynamics, the alternation of sedimentation and erosion processes in the estuary can generate net sedimentary balances through a tide cycle [17,18].The installation of hydraulic reservoirs in upstream areas affects the hydrodynamic equilibrium and sedimentary balances downstream, due to the flood water regulation and the decrease of the solid sediments supply [19][20][21][22][23][24][25]. Blott) [26] concluded that the morphodynamic evolution of Mersey estuary in England through a period of 150 years was mainly controlled by engineering and rehabilitation works, such as the construction of training walls and dredging. Besides, the importance of other factors, notably sea level change, tide amplitude, wave current, and supply of fresh water was relatively reduced [26].The perturbation of estuarine hydrodynamics is permanently regulated by morphologic transformations through sedimentation and erosion processes mobilized to re-establish the hydrodynamic equilibrium [21,22,27]. The morphodynamic change concerns the estuary outlet, the main channel, and the intertidal plains [19,20,28]. In addition, the morphodynamic change in the estuary affects the morphology of neighboring littoral areas and, consequently, causes the shoreline fluctuation [3,[29][30][31]. Numerous works have analyzed the morphologic evolution of coastal systems t...

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The influence of human activities on morphodynamics and alteration of sediment source and sink in the Changjiang Estuary

Cited by 79 publications

References 47 publications

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas

Decadal morphological evolution of the mouth zone of the Yangtze Estuary in response to human interventions

Impact of Anthropogenic Facilities on the Morphodynamic Evolution of an Estuarine System: The Case of Oum Er-Rbia Estuary (Azemmour, Morocco)

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