Morphodynamic impacts of large-scale engineering projects in the Yangtze River delta

Luan, Hua Long; Ding, Pingxing; Wang, Zheng Bing; Yang, S.L.; Lu, Jin-You

doi:10.1016/j.coastaleng.2018.08.013

Cited by 55 publications

(21 citation statements)

References 70 publications

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“…This process is primarily achieved through the transport and accumulation of river sediments and is manifested in the macro‐geomorphology of the channel scour, dynamic equilibrium, and siltation (Zheng et al, 2018). However, if the intensity of external disturbances exceeds the channel strain threshold, destabilization phenomena, such as severe erosion, deposition, and bank collapse, may occur (Luan, Ding, Wang, Yang, & Lu, 2018; Zheng et al, 2018). Besides, human activities also can change channel topography.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have shown that the operation of the Three Gorges Dam (TGD) has reduced the sediment load by 74% compared to that in 1950–1985 (Guo et al, 2019; Zhu et al, 2019). Numerous harbors and human infrastructure have been constructed in the upper reaches of YE, which have a profound impact on channel morphological deformation (Luan et al, 2018). For example, Wang et al (2009) reported that the Jiangsu reach of the YR changed from a depositional environment to an erosion environment around 1985.…”

Section: Introductionmentioning

confidence: 99%

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Morphological response of the upper Yangtze Estuary to changes in natural and anthropogenic factors

Zhang

Wang

Dong

et al. 2022

River Research & Apps

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Globally, over the past few decades, extreme river channel deformation has been observed downstream of dams. Specially, estuarine channel deformation and its response to natural and anthropogenic factors are key issues influencing channel regulation and prediction of long‐term stability in large estuarine deltas. Herein, bathymetry data for the upper reaches of the Yangtze Estuary (YE), China was collected for the years 1995, 2003, 2008, 2013, and 2019 to analyze the channel deformation process. Our findings show that the total erosion volume was approximately 11.22 × 108 m3, an equivalent of 15.7 × 108 t of sediment assuming a bulk density of 1.4 t/m3 for the riverbed material during 1995–2019. Meanwhile, the annual erosion rate is 0.63 Mt/year in 1995–2019, and the annual erosion rate is 0.90, 0.12, 0.40 Mt/year in 1995–2003, 2008–2013 and 2013–2019, respectively. Meanwhile, the annual deposition rate is 0.7 Mt/year during 2003–2008. Further analysis indicated that continuous reduction of the sediment load due to the construction of dams (e.g., the Three Gorges Dam) in the basin was a key factor influencing channel erosion over the past 24 years. The channel deformation process was characterized by severe erosion during 1995–2003, a deposition period during 2003–2008, a dynamic equilibrium period from 2008–2013, and an erosion period after 2013. Due to floods with maximum peak discharge lower than 70,000 m3/s, despite the annual sediment load is reduced, the channel deposition phenomenon occurred in 2003–2008. The channel changed from a depositional system to an erosion system during 2008–2013. After 2013, the channel was dominated by extensive erosion, severe local deposition, or severe local erosion as a response to anthropogenic interventions. These findings are of great significance to river management and regulation, as well as to the navigational safety.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Morphological response of the upper Yangtze Estuary to changes in natural and anthropogenic factors

Zhang

Wang

Dong

et al. 2022

River Research & Apps

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“…This was done to evaluate the future capacity of these highly modified/novel ecosystems to provide sustainable riparian habitat, and to determine the potential ecological benefits of dismantling the engineered structures as part of a river-wide restoration program (Thorel et al, 2018). Though the particular configuration, timing and scale of the river transformation is specific to the Rhône River, the fact that these same influences have been imposed on many large, multi-use rivers in Europe (e.g., Arnaud et al, 2015;Hein et al, 2016), North America (e.g., Alexander et al, 2012Johnson et al, 2015) and elsewhere (e.g., Luan et al, 2018;Wohl, 2019) highlights the applicability of this study to other regions globally.…”

Section: Introductionmentioning

confidence: 99%

Long-term river management legacies strongly alter riparian forest attributes and constrain restoration strategies along a large, multi-use river

Janssen

Stella

Räpple

et al. 2021

Journal of Environmental Management

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Many terrestrial ecosystems have undergone profound transformation under the pressure of multiple human stressors. This may have oriented altered ecosystems toward transient or new states. Understanding how these cumulative impacts influence ecosystem functions, services and ecological trajectories is therefore essential to defining effective restoration strategies. This is particularly the case in riverine ecosystems, where the profound alteration of natural disturbance regimes can make the effectiveness of restoration operations questionable. Using the case study of legacy dike fields, i.e., area delimited by longitudinal and lateral dikes, along the regulated Rhône River, we studied the impacts of long-term channelization and flow regulation on environmental conditions and riparian forests attributes along a 200km climatic gradient. We characterized the imprint of human stressors on these forests by comparing the dike field stands to more natural stands in both young and mature vegetation stages. Across four reaches of the river between Lyon and the Mediterranean Sea, we found that channelization consistently promoted high rate of overbank sedimentation and rapid disconnection of dike field surfaces from the channel. The rapid terrestrialisation of dike field surfaces, i.e., the process by which former aquatic areas transition to a terrestrial ecosystem as a result of dewatering or sedimentation, fostered a pulse of riparian forest regeneration in these resource-rich environments that differs from more natural sites in structure and composition. Within the dike fields, older pre-dam stands are dominated by post-pioneer and exotic species, and post-dam stands support large, aging pioneer trees with a largely exotic understory regeneration layer. These patterns were associated with differences in the relative surface elevation among dike fields, whereas species shifts generally followed the river's longitudinal climate gradient. To enhance the functionality of these human-made ecosystems, restoration strategies should target the reconnection of dike fields to the river by dismantling part of the dikes to promote lateral erosion, forest initiation and community succession, as well as increasing minimum flows in channels to improve connection with groundwater. However, since a river-wide return to a pre-disturbance state is very unlikely, a pragmatic approach should be favoured, focusing on local 3 actions that can improve abiotic and biotic function, and ultimately enhancing ecosystem services such biodiversity, habitat, and recreation opportunities.

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“…The main drawback of the latter is that these simulations require extensive calibration and validation which is not easy to perform [5]. However, there are still some aspects of the dynamics of these systems that have not been analyzed in depth, despite the fact that a significant number of the world's main bays and estuaries are made up of interconnected basins, including the San Francisco Bay [19,20], the Chesapeake Bay [21], the Yangtze River estuary [22,23] or the Harvey River estuary [24].…”

Section: Introductionmentioning

confidence: 99%

Beyond Human Interventions on Complex Bays: Effects on Water and Wave Dynamics (Study Case Cádiz Bay, Spain)

Zarzuelo

López‐Ruiz

Ortega-Sánchez

2020

Water

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Bays are coastal environments with significant socio-economic importance, which has led to the development of human interventions in their interior that can have an important impact on the water and wave dynamics, which in turn modify their morphodynamics and water renewal capacity. In order to deepen our understanding of these impacts, numerical modeling was used in a bay in southern Spain to analyze the effect of inner harbor expansion and channel deepening, including the baroclinic and wave propagation effects, as well as variations in salinity and temperature. The results show that the deepening of the channel decreases the amplitude and speed of the tidal wave as it propagates through the bay, reducing the effects of friction and increasing the flushing time. The system evolves from convergent to a damping system that can potentially reduce the effects produced by projected sea level rise. In addition, the seasonal variability of salinity and temperature is reduced, increasing the bed shear stresses and resulting in increased turbidity that can affect the biogeochemistry of the bay. Finally, wave heights decrease along the main waterway, although the yearly-average wave energy flux is only slightly modified on the interior beaches of the bay. However, significant variations are observed during storms, which could affect the morphodynamics of these beaches.

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Morphodynamic impacts of large-scale engineering projects in the Yangtze River delta

Cited by 55 publications

References 70 publications

Morphological response of the upper Yangtze Estuary to changes in natural and anthropogenic factors

Morphological response of the upper Yangtze Estuary to changes in natural and anthropogenic factors

Long-term river management legacies strongly alter riparian forest attributes and constrain restoration strategies along a large, multi-use river

Beyond Human Interventions on Complex Bays: Effects on Water and Wave Dynamics (Study Case Cádiz Bay, Spain)

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