Y. Kuai
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1
Journal article
(2025)
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Zaiyang Zhou, Yu Kuai, Jianzhong Ge, Bas van Maren, Zhenwu Wang, Kailin Huang, Pingxing Ding, Zhengbing Wang
Physics-informed neural networks (PINNs) are increasingly being used in various scientific disciplines. However, dealing with non-stationary physical processes remains a significant challenge in such models, whereas fluid motions are typically non-stationary. In this study, a PINN-based method was designed and optimized to solve non-stationary fluid dynamics with shallow water equations in a polar coordinate system (PINN-SWEP). It was developed and validated with a classic circular basin case that is well-documented in scientific literature. In the validation case, the wind-induced water surface fluctuations are less than 1 cm, posing challenges in modeling. However, our PINN-SWEP model can accurately simulate such tiny water surface fluctuations and resolve complex fluid motions based on limited and sparse data. A boundary discontinuity problem associated with the use of a polar coordinate system is further discussed and improved, thereby enhancing the applicability of PINN in water research. The methodology can provide an alternative solution for numerical or analytical solutions with high accuracy.
...
Physics-informed neural networks (PINNs) are increasingly being used in various scientific disciplines. However, dealing with non-stationary physical processes remains a significant challenge in such models, whereas fluid motions are typically non-stationary. In this study, a PINN-based method was designed and optimized to solve non-stationary fluid dynamics with shallow water equations in a polar coordinate system (PINN-SWEP). It was developed and validated with a classic circular basin case that is well-documented in scientific literature. In the validation case, the wind-induced water surface fluctuations are less than 1 cm, posing challenges in modeling. However, our PINN-SWEP model can accurately simulate such tiny water surface fluctuations and resolve complex fluid motions based on limited and sparse data. A boundary discontinuity problem associated with the use of a polar coordinate system is further discussed and improved, thereby enhancing the applicability of PINN in water research. The methodology can provide an alternative solution for numerical or analytical solutions with high accuracy.
Journal article
(2025)
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Zaiyang Zhou, Yu Kuai, Kailin Huang, Dirk Sebastiaan van Maren, Jialin Pang, Zhenwu Wang, Yonghui Zhu, Jianzhong Ge
Accurate and efficient prediction of spatiotemporal variations in the distribution of substances in fluids (SIFs) is crucial for various aspects of fluid mechanics related research and applications, involving for instance, material transport quantification, water quality assessment, and engineering condition analysis. This study proposes a framework for resolving the spatiotemporal distribution of SIFs such as salt and suspended sediment based on water levels and flow velocities. The framework incorporates a deep learning model based on a classic neural operator (DeepONet) architecture, which consists of a feature network and a position network to encode the characteristics of input variables and the problem domain. Numerical simulations were performed to generate the needed datasets. The framework was well-validated by predicting salinity and suspended sediment concentration (SSC) distributions in two idealized cases and a real-word case, demonstrating its efficacy and robustness. Time-series validation further demonstrated the prediction accuracy of the framework. The deep learning model is also capable of enhanced-resolution predictions, enabling the generation of high-resolution spatial distributions of SIFs from low-resolution hydrodynamic data. Both bottom and surface layers of the water column were analyzed, revealing that the mapping relationships between hydrodynamics and SIF distributions can be accurately captured throughout the water column, despite variations in correlation coefficients. Due to these capabilities and advantages, additional data sources can be integrated into the framework in the future, highlighting its considerable potential for broader applications in aquatic environments.
...
Accurate and efficient prediction of spatiotemporal variations in the distribution of substances in fluids (SIFs) is crucial for various aspects of fluid mechanics related research and applications, involving for instance, material transport quantification, water quality assessment, and engineering condition analysis. This study proposes a framework for resolving the spatiotemporal distribution of SIFs such as salt and suspended sediment based on water levels and flow velocities. The framework incorporates a deep learning model based on a classic neural operator (DeepONet) architecture, which consists of a feature network and a position network to encode the characteristics of input variables and the problem domain. Numerical simulations were performed to generate the needed datasets. The framework was well-validated by predicting salinity and suspended sediment concentration (SSC) distributions in two idealized cases and a real-word case, demonstrating its efficacy and robustness. Time-series validation further demonstrated the prediction accuracy of the framework. The deep learning model is also capable of enhanced-resolution predictions, enabling the generation of high-resolution spatial distributions of SIFs from low-resolution hydrodynamic data. Both bottom and surface layers of the water column were analyzed, revealing that the mapping relationships between hydrodynamics and SIF distributions can be accurately captured throughout the water column, despite variations in correlation coefficients. Due to these capabilities and advantages, additional data sources can be integrated into the framework in the future, highlighting its considerable potential for broader applications in aquatic environments.
Journal article
(2025)
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Zaiyang Zhou, Jianzhong Ge, Dirk Sebastiaan Van Maren, Hualong Luan, Wenyun Guo, Jianfei Ma, Yingjia Tao, Peng Xu, Yu Kuai, More Authors...
A comprehensive multi-year field campaign, the North Passage Channel Measurements (NP-ChaM), was designed and executed to enhance our understanding of the hydrodynamics and sediment dynamics in the North Passage, the primary navigation channel of the Changjiang Estuary, China. The NP-ChaM campaign comprised eight observational sites and spanned 50 d, distributed over 4 years, including two dry seasons and two wet seasons. A series of tripod systems, equipped with multiple instruments, were deployed on the seabed to monitor near-bed physical processes reliably.
The resulting dataset comprises the following: (i) fluid motions, encompassing pressure, flow velocity and direction (at the bottom and throughout the entire water column), and wave patterns; (ii) near-bed environmental conditions, including temperature, salinity, and turbidity (at the bottom and across a near-bed 1-meter range); (iii) supplementary meteorological data sourced from credible providers; and (iv) preliminary results from post-processing, showcasing the practical application of the data, such as lateral flows and turbulent kinetic energy characterizations.
This dataset is especially valuable due to its extensive temporal and spatial coverage, as well as the high concentrations characterizing many of the observations (from several grams per liter to tens of grams per liter). Conducted annually from 2015 to 2018, the NP-ChaM campaign facilitated detailed observations of seasonal variations in environmental conditions and associated physical processes. The eight observational sites, positioned on either side of the deep channel, enable quantifications of channel–shoal exchanges, along-channel flow dynamics, and saltwater intrusion. This dataset is suitable for advancing our understanding of along-channel and cross-channel dynamics in a channel–shoal system and for calibrating numerical models. The dataset has undergone rigorous quality control to ensure reliability and accuracy. ...
The resulting dataset comprises the following: (i) fluid motions, encompassing pressure, flow velocity and direction (at the bottom and throughout the entire water column), and wave patterns; (ii) near-bed environmental conditions, including temperature, salinity, and turbidity (at the bottom and across a near-bed 1-meter range); (iii) supplementary meteorological data sourced from credible providers; and (iv) preliminary results from post-processing, showcasing the practical application of the data, such as lateral flows and turbulent kinetic energy characterizations.
This dataset is especially valuable due to its extensive temporal and spatial coverage, as well as the high concentrations characterizing many of the observations (from several grams per liter to tens of grams per liter). Conducted annually from 2015 to 2018, the NP-ChaM campaign facilitated detailed observations of seasonal variations in environmental conditions and associated physical processes. The eight observational sites, positioned on either side of the deep channel, enable quantifications of channel–shoal exchanges, along-channel flow dynamics, and saltwater intrusion. This dataset is suitable for advancing our understanding of along-channel and cross-channel dynamics in a channel–shoal system and for calibrating numerical models. The dataset has undergone rigorous quality control to ensure reliability and accuracy. ...
A comprehensive multi-year field campaign, the North Passage Channel Measurements (NP-ChaM), was designed and executed to enhance our understanding of the hydrodynamics and sediment dynamics in the North Passage, the primary navigation channel of the Changjiang Estuary, China. The NP-ChaM campaign comprised eight observational sites and spanned 50 d, distributed over 4 years, including two dry seasons and two wet seasons. A series of tripod systems, equipped with multiple instruments, were deployed on the seabed to monitor near-bed physical processes reliably.
The resulting dataset comprises the following: (i) fluid motions, encompassing pressure, flow velocity and direction (at the bottom and throughout the entire water column), and wave patterns; (ii) near-bed environmental conditions, including temperature, salinity, and turbidity (at the bottom and across a near-bed 1-meter range); (iii) supplementary meteorological data sourced from credible providers; and (iv) preliminary results from post-processing, showcasing the practical application of the data, such as lateral flows and turbulent kinetic energy characterizations.
This dataset is especially valuable due to its extensive temporal and spatial coverage, as well as the high concentrations characterizing many of the observations (from several grams per liter to tens of grams per liter). Conducted annually from 2015 to 2018, the NP-ChaM campaign facilitated detailed observations of seasonal variations in environmental conditions and associated physical processes. The eight observational sites, positioned on either side of the deep channel, enable quantifications of channel–shoal exchanges, along-channel flow dynamics, and saltwater intrusion. This dataset is suitable for advancing our understanding of along-channel and cross-channel dynamics in a channel–shoal system and for calibrating numerical models. The dataset has undergone rigorous quality control to ensure reliability and accuracy.
The resulting dataset comprises the following: (i) fluid motions, encompassing pressure, flow velocity and direction (at the bottom and throughout the entire water column), and wave patterns; (ii) near-bed environmental conditions, including temperature, salinity, and turbidity (at the bottom and across a near-bed 1-meter range); (iii) supplementary meteorological data sourced from credible providers; and (iv) preliminary results from post-processing, showcasing the practical application of the data, such as lateral flows and turbulent kinetic energy characterizations.
This dataset is especially valuable due to its extensive temporal and spatial coverage, as well as the high concentrations characterizing many of the observations (from several grams per liter to tens of grams per liter). Conducted annually from 2015 to 2018, the NP-ChaM campaign facilitated detailed observations of seasonal variations in environmental conditions and associated physical processes. The eight observational sites, positioned on either side of the deep channel, enable quantifications of channel–shoal exchanges, along-channel flow dynamics, and saltwater intrusion. This dataset is suitable for advancing our understanding of along-channel and cross-channel dynamics in a channel–shoal system and for calibrating numerical models. The dataset has undergone rigorous quality control to ensure reliability and accuracy.
Sustainable management of muddy tidal flats
A case study of the Jiangsu coast, China
Tidal flats play a critical role in coastal systems. They serve as essential buffers that protect inland communities from flooding by storm surges, contribute significantly to the maintenance of coastal biodiversity, and function as crucial sites for carbon sequestration. Moreover, they are indispensable for land reclamation projects, supporting economic activities such as agriculture and aquaculture. However, rapid coastal economic development and assertive human interventions have intensified conflicts of interest between socio-economic demands and the preservation of these fragile ecosystems. This increasing tension underscores the necessity for a detailed understanding of tidal flat evolution and the complex interplay between natural processes and anthropogenic activities.
This research aims to deepen our understanding of unvegetated tidal flat morphodynamics by examining both natural processes and the impacts of human interventions. The insights gained will provide valuable theoretical guidance for the sustainable and effective management of tidal flat resources in the future. To achieve this, the study focuses on tidal flats along the Jiangsu Coast in China as a case study. Because it is a typical example famous for its extensive and diverse tidal flat systems. At the same time, it has a long history of coastal land reclamations. A multi-faceted approach is adopted, combining field dataset analysis, a process-based Delft3D model, and a hybrid DET-ESTMORF model, which together provide a robust foundation for theoretical insights in sustainable coastal management.
Based on a unique field measurement data along the Jiangsu Coast, the morphology and sediment characteristics of the unvegetated intertidal flats along this coast are analysed. Both cross-shore and alongshore variations are observed. In the cross-shore direction, sediments exhibit a pronounced coarsening from the landward to the seaward side, indicating tide-dominated forcing. In the alongshore direction, the coast is divided into two parts depending on its morphological state. The northern coast, which is predominantly eroding, exhibits steeper intertidal slopes and a complex mix of sediment types, ranging from extremely fine to coarse deposits. The variation in sediment composition is attributed to natural processes such as self-weight consolidation and surface armouring. In the accreting southern coast, while tidal flat slopes are generally becoming milder towards the south, the corresponding bed surface sediment grain size is becoming coarser southward. This relationship between slope and sediment grain size in the southern coast is opposite to the findings on other muddy tidal flats.
In order to investigate the mechanism behind the region-specific alongshore pattern of the southern Jiangsu Coast, we formulate a conceptual model with special focus on describing the alongshore variations in hydrodynamics and shoreline evolution. Subsequently, a highly schematized Delft3D numerical model is employed in diagnostic mode. By integrating these approaches, the sediment provenance is found to be the sole factor capable of explaining the observed pattern.
Apart from natural processes, anthropogenic activities can also induce significant changes in tidal flat morphology. Available information on the tidal flat morphological responses to human interventions is limited based on the single-time measurements data. We therefore evaluate the resilience of tidal flats to anthropogenic disturbances (specifically, upper flat enclosure reclamation) using an extended DET-ESTMORF model. A series of sensitivity tests under various environmental conditions is conducted with this model. Our findings indicate that the concave or convex shape of tidal flat profiles is primarily governed by dominant hydrodynamic forces (whether tidal or wave-driven), while other variables modulate the profile slope. For a tidal flat to revert to its pre-reclamation configuration, it must exhibit continuous seaward progradation under natural conditions. Such restoration typically occurs in environments with abundant sediment supply, subdued wave activity, and the absence of cross-shore constraints imposed by shore-parallel tidal channels.
Overall, the insights derived from this study enhance our understanding of the interactions between natural hydrodynamic processes, sediment dynamics, morphology change and human-induced alterations. The findings highlight the importance of continuous monitoring and the adoption of adaptive management strategies to ensure that coastal development preserves the ecological integrity and long-term stability of tidal flat systems.
...
This research aims to deepen our understanding of unvegetated tidal flat morphodynamics by examining both natural processes and the impacts of human interventions. The insights gained will provide valuable theoretical guidance for the sustainable and effective management of tidal flat resources in the future. To achieve this, the study focuses on tidal flats along the Jiangsu Coast in China as a case study. Because it is a typical example famous for its extensive and diverse tidal flat systems. At the same time, it has a long history of coastal land reclamations. A multi-faceted approach is adopted, combining field dataset analysis, a process-based Delft3D model, and a hybrid DET-ESTMORF model, which together provide a robust foundation for theoretical insights in sustainable coastal management.
Based on a unique field measurement data along the Jiangsu Coast, the morphology and sediment characteristics of the unvegetated intertidal flats along this coast are analysed. Both cross-shore and alongshore variations are observed. In the cross-shore direction, sediments exhibit a pronounced coarsening from the landward to the seaward side, indicating tide-dominated forcing. In the alongshore direction, the coast is divided into two parts depending on its morphological state. The northern coast, which is predominantly eroding, exhibits steeper intertidal slopes and a complex mix of sediment types, ranging from extremely fine to coarse deposits. The variation in sediment composition is attributed to natural processes such as self-weight consolidation and surface armouring. In the accreting southern coast, while tidal flat slopes are generally becoming milder towards the south, the corresponding bed surface sediment grain size is becoming coarser southward. This relationship between slope and sediment grain size in the southern coast is opposite to the findings on other muddy tidal flats.
In order to investigate the mechanism behind the region-specific alongshore pattern of the southern Jiangsu Coast, we formulate a conceptual model with special focus on describing the alongshore variations in hydrodynamics and shoreline evolution. Subsequently, a highly schematized Delft3D numerical model is employed in diagnostic mode. By integrating these approaches, the sediment provenance is found to be the sole factor capable of explaining the observed pattern.
Apart from natural processes, anthropogenic activities can also induce significant changes in tidal flat morphology. Available information on the tidal flat morphological responses to human interventions is limited based on the single-time measurements data. We therefore evaluate the resilience of tidal flats to anthropogenic disturbances (specifically, upper flat enclosure reclamation) using an extended DET-ESTMORF model. A series of sensitivity tests under various environmental conditions is conducted with this model. Our findings indicate that the concave or convex shape of tidal flat profiles is primarily governed by dominant hydrodynamic forces (whether tidal or wave-driven), while other variables modulate the profile slope. For a tidal flat to revert to its pre-reclamation configuration, it must exhibit continuous seaward progradation under natural conditions. Such restoration typically occurs in environments with abundant sediment supply, subdued wave activity, and the absence of cross-shore constraints imposed by shore-parallel tidal channels.
Overall, the insights derived from this study enhance our understanding of the interactions between natural hydrodynamic processes, sediment dynamics, morphology change and human-induced alterations. The findings highlight the importance of continuous monitoring and the adoption of adaptive management strategies to ensure that coastal development preserves the ecological integrity and long-term stability of tidal flat systems.
...
Tidal flats play a critical role in coastal systems. They serve as essential buffers that protect inland communities from flooding by storm surges, contribute significantly to the maintenance of coastal biodiversity, and function as crucial sites for carbon sequestration. Moreover, they are indispensable for land reclamation projects, supporting economic activities such as agriculture and aquaculture. However, rapid coastal economic development and assertive human interventions have intensified conflicts of interest between socio-economic demands and the preservation of these fragile ecosystems. This increasing tension underscores the necessity for a detailed understanding of tidal flat evolution and the complex interplay between natural processes and anthropogenic activities.
This research aims to deepen our understanding of unvegetated tidal flat morphodynamics by examining both natural processes and the impacts of human interventions. The insights gained will provide valuable theoretical guidance for the sustainable and effective management of tidal flat resources in the future. To achieve this, the study focuses on tidal flats along the Jiangsu Coast in China as a case study. Because it is a typical example famous for its extensive and diverse tidal flat systems. At the same time, it has a long history of coastal land reclamations. A multi-faceted approach is adopted, combining field dataset analysis, a process-based Delft3D model, and a hybrid DET-ESTMORF model, which together provide a robust foundation for theoretical insights in sustainable coastal management.
Based on a unique field measurement data along the Jiangsu Coast, the morphology and sediment characteristics of the unvegetated intertidal flats along this coast are analysed. Both cross-shore and alongshore variations are observed. In the cross-shore direction, sediments exhibit a pronounced coarsening from the landward to the seaward side, indicating tide-dominated forcing. In the alongshore direction, the coast is divided into two parts depending on its morphological state. The northern coast, which is predominantly eroding, exhibits steeper intertidal slopes and a complex mix of sediment types, ranging from extremely fine to coarse deposits. The variation in sediment composition is attributed to natural processes such as self-weight consolidation and surface armouring. In the accreting southern coast, while tidal flat slopes are generally becoming milder towards the south, the corresponding bed surface sediment grain size is becoming coarser southward. This relationship between slope and sediment grain size in the southern coast is opposite to the findings on other muddy tidal flats.
In order to investigate the mechanism behind the region-specific alongshore pattern of the southern Jiangsu Coast, we formulate a conceptual model with special focus on describing the alongshore variations in hydrodynamics and shoreline evolution. Subsequently, a highly schematized Delft3D numerical model is employed in diagnostic mode. By integrating these approaches, the sediment provenance is found to be the sole factor capable of explaining the observed pattern.
Apart from natural processes, anthropogenic activities can also induce significant changes in tidal flat morphology. Available information on the tidal flat morphological responses to human interventions is limited based on the single-time measurements data. We therefore evaluate the resilience of tidal flats to anthropogenic disturbances (specifically, upper flat enclosure reclamation) using an extended DET-ESTMORF model. A series of sensitivity tests under various environmental conditions is conducted with this model. Our findings indicate that the concave or convex shape of tidal flat profiles is primarily governed by dominant hydrodynamic forces (whether tidal or wave-driven), while other variables modulate the profile slope. For a tidal flat to revert to its pre-reclamation configuration, it must exhibit continuous seaward progradation under natural conditions. Such restoration typically occurs in environments with abundant sediment supply, subdued wave activity, and the absence of cross-shore constraints imposed by shore-parallel tidal channels.
Overall, the insights derived from this study enhance our understanding of the interactions between natural hydrodynamic processes, sediment dynamics, morphology change and human-induced alterations. The findings highlight the importance of continuous monitoring and the adoption of adaptive management strategies to ensure that coastal development preserves the ecological integrity and long-term stability of tidal flat systems.
This research aims to deepen our understanding of unvegetated tidal flat morphodynamics by examining both natural processes and the impacts of human interventions. The insights gained will provide valuable theoretical guidance for the sustainable and effective management of tidal flat resources in the future. To achieve this, the study focuses on tidal flats along the Jiangsu Coast in China as a case study. Because it is a typical example famous for its extensive and diverse tidal flat systems. At the same time, it has a long history of coastal land reclamations. A multi-faceted approach is adopted, combining field dataset analysis, a process-based Delft3D model, and a hybrid DET-ESTMORF model, which together provide a robust foundation for theoretical insights in sustainable coastal management.
Based on a unique field measurement data along the Jiangsu Coast, the morphology and sediment characteristics of the unvegetated intertidal flats along this coast are analysed. Both cross-shore and alongshore variations are observed. In the cross-shore direction, sediments exhibit a pronounced coarsening from the landward to the seaward side, indicating tide-dominated forcing. In the alongshore direction, the coast is divided into two parts depending on its morphological state. The northern coast, which is predominantly eroding, exhibits steeper intertidal slopes and a complex mix of sediment types, ranging from extremely fine to coarse deposits. The variation in sediment composition is attributed to natural processes such as self-weight consolidation and surface armouring. In the accreting southern coast, while tidal flat slopes are generally becoming milder towards the south, the corresponding bed surface sediment grain size is becoming coarser southward. This relationship between slope and sediment grain size in the southern coast is opposite to the findings on other muddy tidal flats.
In order to investigate the mechanism behind the region-specific alongshore pattern of the southern Jiangsu Coast, we formulate a conceptual model with special focus on describing the alongshore variations in hydrodynamics and shoreline evolution. Subsequently, a highly schematized Delft3D numerical model is employed in diagnostic mode. By integrating these approaches, the sediment provenance is found to be the sole factor capable of explaining the observed pattern.
Apart from natural processes, anthropogenic activities can also induce significant changes in tidal flat morphology. Available information on the tidal flat morphological responses to human interventions is limited based on the single-time measurements data. We therefore evaluate the resilience of tidal flats to anthropogenic disturbances (specifically, upper flat enclosure reclamation) using an extended DET-ESTMORF model. A series of sensitivity tests under various environmental conditions is conducted with this model. Our findings indicate that the concave or convex shape of tidal flat profiles is primarily governed by dominant hydrodynamic forces (whether tidal or wave-driven), while other variables modulate the profile slope. For a tidal flat to revert to its pre-reclamation configuration, it must exhibit continuous seaward progradation under natural conditions. Such restoration typically occurs in environments with abundant sediment supply, subdued wave activity, and the absence of cross-shore constraints imposed by shore-parallel tidal channels.
Overall, the insights derived from this study enhance our understanding of the interactions between natural hydrodynamic processes, sediment dynamics, morphology change and human-induced alterations. The findings highlight the importance of continuous monitoring and the adoption of adaptive management strategies to ensure that coastal development preserves the ecological integrity and long-term stability of tidal flat systems.
Journal article
(2023)
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Zaiyang Zhou, Jianzhong Ge, D. S. Van Maren, Yu Kuai, Pingxing Ding, Zheng Bing Wang
Existing knowledge about groyne-induced effects is primarily based on riverine or coastal environments where salinity gradients are absent or limited. However, in estuaries, salinity gradients drive physical processes such as longitudinal and lateral residual flows. The effect of groynes is much more complex because they can modulate channel hydrodynamics and directly affect lateral salinity gradients. In this study, an idealized model is applied to investigate the effects of groyne layouts in estuarine environments, including effects on (1) channel hydrodynamics, (2) lateral water exchange, (3) Coriolis effects, and (4) saltwater intrusion. Model results show that the aspect ratio (the width of groyne fields to the length of groynes) of groyne fields plays an important role. Groynes also induce asymmetry of lateral flows, for example, increasing near-bottom shoal-to-channel flows during low water slack. The aspect ratio has opposite effects on horizontal and vertical components of water exchange. A large aspect ratio strengthens horizontal exchange and weakens density-driven currents. For a large-scale groyne field (several kilometers), Coriolis effects introduce a substantial difference in exchange mechanisms along the north and south banks. A medium range of aspect ratio (2.0-3.0) leads to the strongest saltwater intrusion during both neap and spring tides.
...
Existing knowledge about groyne-induced effects is primarily based on riverine or coastal environments where salinity gradients are absent or limited. However, in estuaries, salinity gradients drive physical processes such as longitudinal and lateral residual flows. The effect of groynes is much more complex because they can modulate channel hydrodynamics and directly affect lateral salinity gradients. In this study, an idealized model is applied to investigate the effects of groyne layouts in estuarine environments, including effects on (1) channel hydrodynamics, (2) lateral water exchange, (3) Coriolis effects, and (4) saltwater intrusion. Model results show that the aspect ratio (the width of groyne fields to the length of groynes) of groyne fields plays an important role. Groynes also induce asymmetry of lateral flows, for example, increasing near-bottom shoal-to-channel flows during low water slack. The aspect ratio has opposite effects on horizontal and vertical components of water exchange. A large aspect ratio strengthens horizontal exchange and weakens density-driven currents. For a large-scale groyne field (several kilometers), Coriolis effects introduce a substantial difference in exchange mechanisms along the north and south banks. A medium range of aspect ratio (2.0-3.0) leads to the strongest saltwater intrusion during both neap and spring tides.
Intertidal flats are of great socio-economic and ecological importance in defending the coastal cities from flooding, providing resources for land reclamations and habits for wildlife. On the intertidal flats, milder profiles are usually featured with finer sediment. However, we find the opposite relationship between the alongshore variation in intertidal slope and sediment grain size on the intertidal flat along the Jiangsu Coast. With a conceptual figure of the hydrodynamics and shoreline evolution on this coast, we hypothesize that the unexpected pattern is caused by the alongshore gradient in hydrodynamic forcing. In order to test our hypothesis, we carry out a series of numerical model simulations in a highly schematized manner to investigate the real mechanism behind this unexpected pattern. Through the analysis, we find that only the southwards coarsening pattern is inconsistent with the shoreline evolution pattern. This inconsistency is not induced by alongshore hydrodynamic gradient, and can only be explained by different sediment provenances. We also find that the alongshore shoreline evolution pattern is not only determined by the alongshore gradient in hydrodynamic forcing, but also influenced by the alongshore variation in bed composition. In the erosion/sedimentation transition zone, the bed composition factor plays the major role.
...
Intertidal flats are of great socio-economic and ecological importance in defending the coastal cities from flooding, providing resources for land reclamations and habits for wildlife. On the intertidal flats, milder profiles are usually featured with finer sediment. However, we find the opposite relationship between the alongshore variation in intertidal slope and sediment grain size on the intertidal flat along the Jiangsu Coast. With a conceptual figure of the hydrodynamics and shoreline evolution on this coast, we hypothesize that the unexpected pattern is caused by the alongshore gradient in hydrodynamic forcing. In order to test our hypothesis, we carry out a series of numerical model simulations in a highly schematized manner to investigate the real mechanism behind this unexpected pattern. Through the analysis, we find that only the southwards coarsening pattern is inconsistent with the shoreline evolution pattern. This inconsistency is not induced by alongshore hydrodynamic gradient, and can only be explained by different sediment provenances. We also find that the alongshore shoreline evolution pattern is not only determined by the alongshore gradient in hydrodynamic forcing, but also influenced by the alongshore variation in bed composition. In the erosion/sedimentation transition zone, the bed composition factor plays the major role.
Tidal flats play an important role in promoting coastal biodiversity, defense against flooding, land reclamation and recreation. Many coastal tidal flats, especially the tide-dominant ones, are muddy. However, the number of studies on the profile shape and surficial sediment distribution of muddy tidal flats is small compared to sandy beaches. Based on high spatial-resolution measurements along the tide-dominant Jiangsu Coast, China, we analyzed the morphology and sediment characteristics of the unvegetated intertidal flats along the Jiangsu Coast. The Jiangsu Coast can be divided into an eroding northern part (north coast) and an accreting southern part (south coast). The beach slope of the north coast shows a southward flattening trend, apart from some outliers related to rocky parts of the coastline. We found alternating very fine and coarse sediment (depending on the local clay content) for different locations along the north coast, which can be explained from consolidation and armoring-induced erosion resistance. In the south coast, we found gradual coarsening of bed surface sediment and gradual flattening of beach slopes to the south. This seemingly unexpected pattern is explained by the flood-dominant current causing landward sediment transport, larger tidal range in the south part, sheltering effect of the Radial Sand Ridges, and contribution of different sediment sources, viz. the Abandoned Yellow River Delta and the Radial Sand Ridges. In the cross-shore direction, the sediment grain size decreases landward. Waves are only of secondary importance for the sediment dynamics at the unvegetated tidal flats along the Jiangsu Coast.
...
Tidal flats play an important role in promoting coastal biodiversity, defense against flooding, land reclamation and recreation. Many coastal tidal flats, especially the tide-dominant ones, are muddy. However, the number of studies on the profile shape and surficial sediment distribution of muddy tidal flats is small compared to sandy beaches. Based on high spatial-resolution measurements along the tide-dominant Jiangsu Coast, China, we analyzed the morphology and sediment characteristics of the unvegetated intertidal flats along the Jiangsu Coast. The Jiangsu Coast can be divided into an eroding northern part (north coast) and an accreting southern part (south coast). The beach slope of the north coast shows a southward flattening trend, apart from some outliers related to rocky parts of the coastline. We found alternating very fine and coarse sediment (depending on the local clay content) for different locations along the north coast, which can be explained from consolidation and armoring-induced erosion resistance. In the south coast, we found gradual coarsening of bed surface sediment and gradual flattening of beach slopes to the south. This seemingly unexpected pattern is explained by the flood-dominant current causing landward sediment transport, larger tidal range in the south part, sheltering effect of the Radial Sand Ridges, and contribution of different sediment sources, viz. the Abandoned Yellow River Delta and the Radial Sand Ridges. In the cross-shore direction, the sediment grain size decreases landward. Waves are only of secondary importance for the sediment dynamics at the unvegetated tidal flats along the Jiangsu Coast.
Study of Sediment Transport in a Tidal Channel-Shoal System
Lateral Effects and Slack-Water Dynamics
Journal article
(2021)
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Zaiyang Zhou, Jianzhong Ge, D. S. van Maren, Zheng Bing Wang, Yu Kuai, Pingxing Ding
Lateral flows redistribute sediment and influence the morphodynamics of channel-shoal systems. However, our understanding of lateral transport of suspended sediment during high and low water slack is still fairly limited, especially in engineered estuaries. Human interventions such as dike-groyne structures influence lateral exchange mechanisms. The present study aims to unravel these mechanisms in a heavily engineered, turbid channel-shoal system in the Changjiang Estuary, using a high-resolution unstructured-grid three-dimensional model and in situ observations. Analysis of model results reveals two typical transport patterns during slack-water conditions, that is, shoal-to-channel transport during low water slack and channel-to-shoal transport during high water slack. A momentum balance analysis is carried out to explain mechanisms driving the lateral transport of suspended sediment during high water slack, revealing the importance of lateral pressure gradients, Coriolis force, and the curvature-induced term. Groyne fields play a crucial role in sediment transport, especially during low water slack. A model scenario in which one groyne is removed reveals that groyne fields strongly influence lateral sediment transport. The decomposition of the sediment transport flux reveals that the turbidity maximum is shaped by a balance between seaward advection by residual flows, and landward transport by tidal pumping and gravitational circulation. Within the turbidity maximum, sediment is laterally redistributed by lateral flows during slack-water conditions, greatly influencing estuarine channel morphology.
...
Lateral flows redistribute sediment and influence the morphodynamics of channel-shoal systems. However, our understanding of lateral transport of suspended sediment during high and low water slack is still fairly limited, especially in engineered estuaries. Human interventions such as dike-groyne structures influence lateral exchange mechanisms. The present study aims to unravel these mechanisms in a heavily engineered, turbid channel-shoal system in the Changjiang Estuary, using a high-resolution unstructured-grid three-dimensional model and in situ observations. Analysis of model results reveals two typical transport patterns during slack-water conditions, that is, shoal-to-channel transport during low water slack and channel-to-shoal transport during high water slack. A momentum balance analysis is carried out to explain mechanisms driving the lateral transport of suspended sediment during high water slack, revealing the importance of lateral pressure gradients, Coriolis force, and the curvature-induced term. Groyne fields play a crucial role in sediment transport, especially during low water slack. A model scenario in which one groyne is removed reveals that groyne fields strongly influence lateral sediment transport. The decomposition of the sediment transport flux reveals that the turbidity maximum is shaped by a balance between seaward advection by residual flows, and landward transport by tidal pumping and gravitational circulation. Within the turbidity maximum, sediment is laterally redistributed by lateral flows during slack-water conditions, greatly influencing estuarine channel morphology.