Morphodynamic changes in the Yangtze Estuary under the impact of the Three Gorges Dam, estuarine engineering interventions and climate-induced sea level rise

Cheng, Heqin; Chen, Wei; Li, J.F.; Jiang, Yuehua; Hu, Xinping; Zhang, X.L.; Zhou, Fengnian; Hu, Fangxi; Stive, M.J.F.

doi:10.1016/j.epsl.2022.117385

Cited by 10 publications

(3 citation statements)

References 40 publications

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“…Remarkably, despite their modest longitudinal extents, these reaches manifest significant topographic undulations both in transverse and longitudinal domains. Such pronounced fluctuations in fluvial topography resonate with observations from the Lower Yangtze River, where features such as catenary-bead subaqueous dunes exceeding 4 m in height and channel scarps surmounting 10 m have been documented (Cheng et al, 2022).…”

Section: 1029/2023wr036660supporting

confidence: 75%

Dune Development Dominates Flow Resistance Increase in a Large Dammed River

Hu,

Li,

Deng

et al. 2024

Water Resources Research

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Dunes are important for bedload transport in almost all large river systems and exert an important control flow resistance. Investigating dunes is fundamental for simulating discharge, sediment transport, and flood routing. However, the spatiotemporal dynamics of dunes and flow resistance remain poorly understood in large alluvial river systems mainly due to the lack of high‐resolution data. Here we analyzed in‐field observed data on annual profiles of 450 cross‐sections, river bathymetry, discharge, water levels, and sediment in the Middle Yangtze River, and found that dunes developed and flow resistance increased (+10%) in the post‐Three Gorges Dam period. We ascertain that the development of dunes plays the dominant role in augmenting flow resistance, as evidenced by roughness height change (+29%) using a modified Van Rijn method. Ultimately, dune development was incorporated into a hydrogeomorphic numerical model of the Yangtze River to improve flow resistance quantification, and thus, the water level simulation. Our findings highlight the potential increase in flow resistance in response to upstream damming in large rivers and have important implications for flood management and riverine ecology.

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Section: 1029/2023wr036660supporting

confidence: 75%

Dune Development Dominates Flow Resistance Increase in a Large Dammed River

Hu,

Li,

Deng

et al. 2024

Water Resources Research

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“…Cheng HQ et al [29] analyses morphometric changes in the Yangtze Estuary from fine bathymetric surveys since 2013 and highlight three different drivers of these changes: They show erosions and redeposits of sediment in the estuary with new forms including extensive areas of subaqueous dunes in the estuarine channel with maximum turbidity. These morphodynamic transformations result from a combination of an abrupt decrease in sediment supply resulting from the construction of the Three Gorges Dam (TGD) and hydrodynamic changes caused by sea level rise.…”

Section: Methods and Data To Study Coastal Dynamics In Estuaries And ...mentioning

confidence: 99%

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2023

EIMBO

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The river streams meet the sea level either by estuaries in which the ocean flows more or less far, or by deltas, large sedimentary constructions reclaimed from the sea. The coastal dynamics of estuaries and deltas is very dependent on the difference in altitude between sea level and the bottom of the riverbed at its mouth, on the sedimentary loading transported by the river at sea, on the erosive force of the tides and on the marine currents. Among these drivers, two are rapidly changing in the Anthropocene: i) The rise of sea level due to climate change or various digging engineering works, ii) The rate of sediment transported by rivers due to the multiplication of large dams or more land husbandry inside the watershed. This review paper recalls the importance of estuaries and deltas, places with high populations due to the port sites they shelter, the richness of the alluvial lands or the importance of mangroves for natural resources and biodiversity. They indicate the principles that drive their formation and evolution. They show from the literature the important changes at the mouths of major rivers during the Anthropocene. Finally, they detail the evolution of the Medjerda Delta in Tunisia, well known since antiquity. Recent studies show the speed of its construction since the Punic period and the even faster reopening of the Gulf of Utica since the construction of large dams, the recent change of land use in the river basin and the rise in sea level. They conclude with a discussion on this global trend of the invasion of estuaries and deltas by the sea.

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“…The identification of these sedimentary structures provides realistic seafloor representation to hydrodynamic simulation models involved in flood risk assessment in coastal areas. The recognition of dunes on the seafloor can also be used in the study of the sand banks erosion [11] and in the changes of the morpho-sedimentary dynamics of the seafloor [12]. They also contribute to the temporal monitoring of marine habitats [13].…”

Section: Introductionmentioning

confidence: 99%

An Approach for the Automatic Characterization of Underwater Dunes in Fluviomarine Context

2022

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The identification of underwater landforms represents an important role in the study of the seafloor morphology. In this context, the segmentation and characterization of underwater dunes allow a better understanding of the dynamism of the seafloor, since the formation of these structures is directly related to environmental conditions, such as current, tide, grain size, etc. In addition, it helps to ensure safe navigation, especially in the context of navigation channels requiring periodic maintenance. This paper proposes a novel method to automatically characterize the underwater dunes. Its originality relies on the extraction of morphological descriptors not only related to the dune itself, but also to the fields where the dunes are located. Furthermore, the proposed approach involves the entire surface of the dunes, rather than profiles or group of pixels as generally found in previous works. Considering the surface modelled by a digital bathymetric model (DBM), the salient features of the dunes (i.e., crest line, stoss trough, and lee trough) are first identified using a geomorphometric analysis of the DBM. The individual dunes are built by matching the crest lines with their respective troughs according to an object-oriented approach. Then, a series of morphological descriptors, selected through a literature review, are computed by taking advantage of the dune salient features, surface representation, and spatial distribution in the fields where they are located. The validation of the proposed method has been conducted using more than 1200 dunes in the fluvio-marine context of the Northern Traverse of the Saint Lawrence River.

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Morphodynamic changes in the Yangtze Estuary under the impact of the Three Gorges Dam, estuarine engineering interventions and climate-induced sea level rise

Cited by 10 publications

References 40 publications

Dune Development Dominates Flow Resistance Increase in a Large Dammed River

Dune Development Dominates Flow Resistance Increase in a Large Dammed River

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An Approach for the Automatic Characterization of Underwater Dunes in Fluviomarine Context

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