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Qingshu Yang - One of the best experts on this subject based on the ideXlab platform.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
Hydrology and Earth System Sciences, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–River Dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
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Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary, China
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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impacts of three gorges dam s operation on spatial temporal patterns of tide River Dynamics in the yangtze River estuary china
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
2018Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping primarily through a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we also demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e., landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary were used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reach), which suggests an important cumulative effect of residual water level on tide-River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide-River Dynamics and the corresponding residual water level slope under various external forcing conditions. It was shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide-River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide-River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
Huayang Cai - One of the best experts on this subject based on the ideXlab platform.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
Hydrology and Earth System Sciences, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–River Dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
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Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary, China
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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impacts of three gorges dam s operation on spatial temporal patterns of tide River Dynamics in the yangtze River estuary china
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
2018Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping primarily through a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we also demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e., landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary were used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reach), which suggests an important cumulative effect of residual water level on tide-River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide-River Dynamics and the corresponding residual water level slope under various external forcing conditions. It was shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide-River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide-River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
Feng Liu - One of the best experts on this subject based on the ideXlab platform.
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Tertiary Regulation of Cascaded Run-of-the-River Hydropower in the Islanded Renewable Power System Considering Multi-Timescale Dynamics.
arXiv: Optimization and Control, 2020Co-Authors: Yiwei Qiu, Feng Liu, Jin Lin, Ningyi Dai, Yonghua Song, Chen Gang, Lijie DingAbstract:To enable power supply in rural areas and to exploit clean energy, fully renewable power systems consisting of cascaded run-of-the-River hydropower and volatile energies such as pv and wind are built around the world. In islanded operation mode, the primary and secondary frequency control, i.e., hydro governors and automatic generation control (AGC), ensure the frequency stability. However, due to limited water storage capacity of run-of-the-River hydropower and River Dynamics constraints, without coordination between the cascaded plants, the traditional AGC with fixed participation factors cannot fully exploit the adjustability of cascaded hydropower. When imbalances between the volatile energy and load occur, load shedding can be inevitable. To address this issue, this paper proposes a coordinated tertiary control approach by jointly considering power system Dynamics and the River Dynamics that couples the cascaded hydropower plants. The timescales of the power system and River Dynamics are very different. To unify the multi-timescale Dynamics to establish a model predictive controller that coordinates the cascaded plants, the relation between AGC parameters and turbine discharge over a time interval is approximated by a data-based second-order polynomial surrogate model. The cascaded plants are coordinated by optimising AGC participation factors in a receding-horizon manner, and load shedding is minimised. Simulation of a real-life system shows a significant improvement in the proposed method in terms of reducing load shedding.
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Multi-Timescale Coordinated AGC of Islanded Microgrids with Cascaded Run-of-the-River Hydropower and Volatile Energies.
arXiv: Optimization and Control, 2020Co-Authors: Yiwei Qiu, Feng Liu, Jin Lin, Yonghua Song, Chen Gang, Lijie DingAbstract:To enable power supply in rural areas and to exploit clean energy, fully renewable microgrids consisting of cascaded run-of-the-River hydropower and volatile energies such as pv and wind power are built around the world. In islanded operation mode, to ensure frequency stability, the automatic generation control (AGC) of hydropower is essential. However, due to the limited water storage capacity of run-of-the-River hydropower and the River Dynamics constraints, without coordination between the cascaded plants, the traditional AGC with fixed participation factors cannot fully exploit the adjustability of cascaded hydropower. When large variations in the volatile energies or load occur, to avoid frequency instability, load shedding can be inevitable, which deteriorates the power supply reliability. To address this issue, this paper proposes a coordinated AGC by jointly considering power system frequency Dynamics and the River Dynamics that couples the cascaded hydropower plants. The timescales of the power system frequency Dynamics and River Dynamics are very different. To unify the multi-timescale Dynamics to establish a model predictive controller that coordinates the cascaded plants, the frequency Dynamics model is approximated as a quasi-stationary one. The cascaded plants are coordinated by optimizing the AGC participation factors in a receding-horizon manner, and load shedding is minimized. Simulation of a real-life microgrid on PSS/E shows a significant improvement in the proposed controller in terms of power supply reliability.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
Hydrology and Earth System Sciences, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–River Dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
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Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary, China
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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impacts of three gorges dam s operation on spatial temporal patterns of tide River Dynamics in the yangtze River estuary china
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
Leicheng Guo - One of the best experts on this subject based on the ideXlab platform.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
Hydrology and Earth System Sciences, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–River Dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
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Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary, China
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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impacts of three gorges dam s operation on spatial temporal patterns of tide River Dynamics in the yangtze River estuary china
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
2018Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping primarily through a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we also demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e., landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary were used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reach), which suggests an important cumulative effect of residual water level on tide-River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide-River Dynamics and the corresponding residual water level slope under various external forcing conditions. It was shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide-River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide-River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
Min Zhang - One of the best experts on this subject based on the ideXlab platform.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
Hydrology and Earth System Sciences, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–River Dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
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Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary, China
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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impacts of three gorges dam s operation on spatial temporal patterns of tide River Dynamics in the yangtze River estuary china
Ocean Science, 2019Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Qingshu YangAbstract:Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River, is the world's largest hydroelectric station in terms of installed power capacity. It was demonstrated that the TGD had caused considerable modifications in the downstream freshwater discharge due to its seasonal operation mode of multiple utilisation for flood control, irrigation, and power generation. To understand the impacts of the freshwater regulation of the TGD, an analytical model is adopted to explore how the operation of the TGD may affect the spatial–temporal patterns of tide–River Dynamics in the Yangtze River estuary. We evaluated the effect of the TGD by comparing the changes in major tide–River Dynamics in the post-TGD period (2003–2014) with those in the pre-TGD period (1979–1984). The results indicate that the strongest impacts occurred during the autumn and winter, corresponding to a substantial reduction in freshwater discharge during the wet-to-dry transition period and slightly increased discharge during the dry season. The underlying mechanism leading to changes in the tide–River Dynamics lies in the alteration of freshwater discharge, while the impact of geometric change is minimal. Overall, the results suggest that the spatial–temporal pattern of tide–River Dynamics is sensitive to the freshwater regulation of the TGD, so that the ecosystem function of the estuary may undergo profound disturbances. The results obtained from this study can be used to set scientific guidelines for water resource management (e.g. navigation, flood control, salt intrusion) in dam-controlled estuarine systems.
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Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and River discharge for maximum tidal damping
2018Co-Authors: Huayang Cai, Xianyi Zhang, Min Zhang, Leicheng Guo, Feng Liu, Hubert H. G. Savenije, Erwan Garel, Qingshu YangAbstract:Abstract. As a tide propagates into the estuary, River discharge affects tidal damping primarily through a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we also demonstrate a third effect of River discharge that may lead to the weakening of the channel convergence (i.e., landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary were used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of River discharge, beyond which the tidal damping is reduced with increasing River discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reach), which suggests an important cumulative effect of residual water level on tide-River Dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide-River Dynamics and the corresponding residual water level slope under various external forcing conditions. It was shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger River discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing River discharge, owing to the cumulative effect of residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide-River Dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide-River interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.
