Dynamic analysis of riverbed evolution: Chengtong Reach of Yangtze Estuary

Chen, Yongping; Li, Jiangxia; Wu, Zhigang; Pan, Shunqi

doi:10.2112/si75-041.1

Cited by 8 publications

(6 citation statements)

References 6 publications

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“…Accordingly, a branching channel with decreasing ebb partition ratio presented a declining trend, and vice versa ( Fig. 6; Chen et al, 2016). Meanwhile, depo-centers in declining branches tended to migrate upstream and become located in the upper subreaches, whereas those in developing branches tended to move downstream into the lower sub-reaches, as demonstrated for recent channel-regulation projects (Wu et al, 2013;Yang and Lin, 2013;Ni et al, 2014).…”

Section: Trends In Channel Erosion-deposition and Depo-center Movementmentioning

confidence: 57%

“…This implies that the higher runoff discharge caused flow to divert into these branches, with the opposite occurring in the other waterway branches. It should be noted that field observations by Chen et al (2016) have shown that the east and west branches of the Langshansha Waterway have exhibited developing and declining trends. (Table 2).…”

Section: Resultsmentioning

confidence: 99%

“…Morphological evolution of river systems is important to river management and regulation, and has become a growing issue over the past decades (Li et al, 2014;Zhu et al, 2017;Schletterer et al, 2019). Braided reaches are commonplace in rivers, with alternate development and shrinkage occurring between the main stem and secondary branches; such reaches often extend from the head source to the estuary (Jain and Sinha, 2004;Latrubesse, 2008;Jansen and Nanson, 2010;Chen et al, 2016;Li et al, 2016;Han et al, 2018;Zhu et al, 2017Zhu et al, , 2019. It has been established that differences in evolutional processes between bifurcated branches are primarily caused by changes in lateral flow dynamics, driven by variations in flow discharge (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…It has been established that differences in evolutional processes between bifurcated branches are primarily caused by changes in lateral flow dynamics, driven by variations in flow discharge (i.e. upstream runoff discharge or downstream tidal discharge) (Chen et al, 2016;Han et al, 2018;Zhu et al, 2017, local human activities (e.g. channel improvement works, and sand excavation) (Kuang et al, 2014;Zheng et al, 2018;Dai and Ding, 2019), and Coriolisinduced circulation in estuarine areas (Wang et al, 2013;Li et al, 2011Li et al, , 2014.…”

Section: Introductionmentioning

confidence: 99%

“…net discharge ratios and flow velocities) in the branching channels of the near-estuary reach (Jiang et al, 2012b;Chen et al, 2012Chen et al, , 2016Fan et al, 2017;Zhang and Xu, 2017), but have not considered overall variations in channel morphology and systemic relationships between erosion-deposition patterns and variations in the flow hydrodynamics. This implies that, predictions of the future evolution of branching channels in this reach (Jiang et al, 2012b;Chen et al, 2016) might be unreliable. Moreover, the law of depo-center movement in the branching channels of the near-estuary reach has not been explored.…”

Section: Introductionmentioning

confidence: 99%

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Erosion-deposition patterns and depo-center movements in branching channels at the near-estuary reach of the Yangtze River

et al. 2020

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Channel evolution and depo-center migrations in braided reaches are significantly influenced by variations in runoff. This study examines the effect of runoff variations on the erosion-deposition patterns and depo-center movements within branching channels of the near-estuary reach of the Yangtze River. We assume that variations in annual mean duration days of runoff discharges, ebb partition ratios in branching channels, and the erosional/depositional rates of entire channels and sub-reaches are representative of variations in runoff intensity, flow dynamics in branching channels, and morphological features in the channels. Our results show that the north region of Fujiangsha Waterway, the Liuhaisha branch of Rugaosha Waterway, the west branch of Tongzhousha Waterway, and the west branch of Langshansha Waterway experience deposition or reduced erosion under low runoff intensity, and erosion or reduced deposition under high runoff intensity, with the depo-centers moving upstream and downstream, respectively. Other waterway branches undergo opposite trends in erosion-deposition patterns and depo-center movements as the runoff changes. These morphological changes may be associated with trends in ebb partition ratio as the runoff discharge rises and falls. By flattening the intra-annual distribution of runoff discharge, dam construction in the Yangtze Basin has altered the ebb partition ratios in waterway branches, affecting their erosion-deposition patterns and depo-center movements. Present trends are likely to continue into the future as a succession of large cascade dams is under construction along the upper Yangtze.

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Section: Trends In Channel Erosion-deposition and Depo-center Movementmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Erosion-deposition patterns and depo-center movements in branching channels at the near-estuary reach of the Yangtze River

et al. 2020

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Quantitative relationship between channels and bars in a tidal reach of the lower Yangtze River: Implications for river management

et al. 2021

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Deep-water navigation channels in the tidal reaches of the lower Yangtze River are affected by water and sediment fluxes that produce complex shoals and unstable channel conditions. The Fujiangsha reach is particularly difficult to manage, as it has many braided channels within the tidal fluctuation zone. In this study, hydrologic and topographic data from the Fujiangsha reach from 2012 to 2017 were used to examine the variations in deposition and erosion, flow diversion, shoals, and channel conditions. Since the Three Gorges Dam became operational and water storage was initiated, the Fujiangsha reach has shown an overall tendency toward erosion. Channels deeper than 10 m accounted for 83.7% of the total erosion of the Fujiangsha reach during 2012-2017. Moreover, the dominant channel-forming sediments have gradually changed from suspended sediments to a mixed load of suspended and bed-load sediments. Deposition volumes of these sediments has varied significantly among different channels, but has mainly occurred in the Fubei channel. Furthermore, periodic variations in the Jingjiang point bar have followed a deposition-erosion-deposition pattern, and the downstream Shuangjian shoal mid-channel bar has been scoured and shortened. Approximately 44.0% of the bed load from the upstream Fujiangsha reach is deposited within the 12.5-m deep Fubei channel. The increased erosion and river flow from the Jingjiang point bar and the Shuangjian shoal during the flood season constituted 59.3% and 40.7%, respectively, of the total amount of siltation in the Fubei channel. Keywords: tidal current; fluctuating reach; point and central bar; channel conditions; quantitative relationship; lower reaches of the Yangtze River; Fujiangsha reach

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Critical threshold of periodic point bar scour and sediment body transport path in tidal reaches: A case study of Fujiangsha reach, Yangtze River

et al. 2023

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The evolution of point bars in changing sections of a downstream tidal current limit is periodic. Accordingly, assessing the critical morphology and hydrodynamic characteristics of point bar scour and the sediment transport process of scour sediment bodies can support river regulation and waterway maintenance. The frequent scour of point bars in changing sections of tidal current limits within the Yangtze River directly restricts waterway stability. This study examined the Fujiangsha reach of the Yangtze River, hydrological data on sediment transport, and riverbed topography from 1950. The Jingjiang bank tail exhibited an evolutionary cycle (siltation>scour>siltation), with a primary period ranging from 3-6 years. Additionally, certain morphological and dynamic conditions were necessary for scour. The Datong station flow (Q) ranged from 20,000-40,000 m 3 •s -1 for ≥180 days•yr -1 , enabling the bank silt layers to widen. Scour occurred during flooding and was concentrated in areas 5.0-7.5 km downstream from Ebizui. When Q≥40,000 m 3 •s -1 , scouring occurred in the bank middle and lower reaches, whereas Q≥50,000 m 3 •s -1 for >50 consecutive days, scour occurred at the tail as well. Moreover, the volume of the scour shoals increased with the number of high-flow days (≥60,000 m 3 •s -1 ). Bottom sand transport mainly occurred in the low-bank zone. Before the project's second phase, the longitudinal transport of the scouring sand bodies occurred as follows: Jingjiang bank > low bank on the north side of Shuangjiansha > Fubei anabranch. During the second phase, the longitudinal transport route changed to Jingjiang bank > Fubei anabranch. The Jingjiang bank volume was also reduced; thus, its development was controlled. Owing to changes in the longitudinal transport routes, dredging should be conducted in areas where scouring sand bodies are separately transported from the tail, thereby reducing the load of dredging and maintenance for the Fubei anabranch

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Dynamic analysis of riverbed evolution: Chengtong Reach of Yangtze Estuary

Cited by 8 publications

References 6 publications

Erosion-deposition patterns and depo-center movements in branching channels at the near-estuary reach of the Yangtze River

Erosion-deposition patterns and depo-center movements in branching channels at the near-estuary reach of the Yangtze River

Quantitative relationship between channels and bars in a tidal reach of the lower Yangtze River: Implications for river management

Critical threshold of periodic point bar scour and sediment body transport path in tidal reaches: A case study of Fujiangsha reach, Yangtze River

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