Oyster aquaculture farm(OAF)with dense wooden stakes,one of the prevalent large-scale marine culture facilities in estuaries,has the potential to influence estuarine hydrodynamics,sediment dynamics,geomorphological ev...Oyster aquaculture farm(OAF)with dense wooden stakes,one of the prevalent large-scale marine culture facilities in estuaries,has the potential to influence estuarine hydrodynamics,sediment dynamics,geomorphological evolution,and sustainable development.This study investigated these impacts in the Moyang River Estuary(Guangdong Province,China)by combining a two-dimentional coupled current-wave-sediment numerical model with field observations based on the TELEMAC-MASCARET numerical simulation system.The wooden stakes of OAF were represented as rigid cylinders in the model,and key parameters were calibrated through field observations,including stake diameter(0.1 m),spacing(3 m),height(6 m),and drag coefficient.Simulations comparing scenarios with and without OAF quantified the responses of sediment dynamics to estuarine OAF.Tidal currents in the channel were strengthened,with velocity increased by 20%-70%,while currents within the OAF weakened,with the maximum reduction exceeding 0.45 m/s.Significant wave height rapidly attenuated within OAF,with the wave attenuation coefficient exceeding 50%.Concurrently,due to the effects of stronger ebb dynamics caused by OAF,sediments in the channel were eroded,inducing a larger rate of seaward residual transport over a tidal cycle.Additionally,more sediments in the middle bar were resuspended,promoting the formation of a high-concentration zone of suspended sediment(estuarine turbidity maximum)during the ebb period.These changes in sediment dynamics caused by OAF significantly influenced the geomorphological evolution of the mouth bar,driving seaward channel extension and deepening,while causing progressive vertical accretion and lateral expansion in the top and outer slope of the middle bar.Sediment resuspension and redistribution within the mouth bar facilitated net transport and redeposition along the OAF periphery.Furthermore,it is crucial to appropriately increase the stakes spacing in the management of oyster farms to ensure a stable flow of water within the OAF.These findings provide a transferable framework for investigating sediment dynamics and a scientific basis for evaluating marine aquaculture practices in other estuaries with OAF or similar anthropogenic structures worldwide.展开更多
Knowledge of sediment variation processes is essential to understand the evolution mechanism of beach morphology changes.Thus,a field measurement was conducted at the Heisha Beach,located on the west coast of the Zhuj...Knowledge of sediment variation processes is essential to understand the evolution mechanism of beach morphology changes.Thus,a field measurement was conducted at the Heisha Beach,located on the west coast of the Zhujiang River(Pearl River)Estuary,to investigate the short-term variation in suspended sediment concentrations(SSCs)and the relationship between the SSC and turbulent kinetic energy,bottom shear stress(BSS),and relative wave height.Based on extreme event analysis results,extreme events have a greater influence on turbulent kinetic energy than SSC.Although a portion of the turbulent kinetic energy dissipates directly into the water column,it plays an important role in suspended sediment motion.Most of the time,the wave-current interaction is strong enough to drive sediment incipience and resuspension.When combined,the wave-current interaction and wave-induced BSSs have a greater influence on suspended sediment transport and SSC variation than current-induced BSS alone.The relative wave height also has a strong correlation with SSC,indicating that the combined effect of water depth and wave height significantly impacts SSC variation.Water depth is mainly controlled by the tide on the beaches;thus,the effects of tides and waves should be conjunctively considered when analyzing the factors influencing SSC.展开更多
基金The Yangjiang Waterway Affairs Center of Guangdong Province Program under contract No.HLSJCG-20220103the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Program under contract No.SML2023SP220.
文摘Oyster aquaculture farm(OAF)with dense wooden stakes,one of the prevalent large-scale marine culture facilities in estuaries,has the potential to influence estuarine hydrodynamics,sediment dynamics,geomorphological evolution,and sustainable development.This study investigated these impacts in the Moyang River Estuary(Guangdong Province,China)by combining a two-dimentional coupled current-wave-sediment numerical model with field observations based on the TELEMAC-MASCARET numerical simulation system.The wooden stakes of OAF were represented as rigid cylinders in the model,and key parameters were calibrated through field observations,including stake diameter(0.1 m),spacing(3 m),height(6 m),and drag coefficient.Simulations comparing scenarios with and without OAF quantified the responses of sediment dynamics to estuarine OAF.Tidal currents in the channel were strengthened,with velocity increased by 20%-70%,while currents within the OAF weakened,with the maximum reduction exceeding 0.45 m/s.Significant wave height rapidly attenuated within OAF,with the wave attenuation coefficient exceeding 50%.Concurrently,due to the effects of stronger ebb dynamics caused by OAF,sediments in the channel were eroded,inducing a larger rate of seaward residual transport over a tidal cycle.Additionally,more sediments in the middle bar were resuspended,promoting the formation of a high-concentration zone of suspended sediment(estuarine turbidity maximum)during the ebb period.These changes in sediment dynamics caused by OAF significantly influenced the geomorphological evolution of the mouth bar,driving seaward channel extension and deepening,while causing progressive vertical accretion and lateral expansion in the top and outer slope of the middle bar.Sediment resuspension and redistribution within the mouth bar facilitated net transport and redeposition along the OAF periphery.Furthermore,it is crucial to appropriately increase the stakes spacing in the management of oyster farms to ensure a stable flow of water within the OAF.These findings provide a transferable framework for investigating sediment dynamics and a scientific basis for evaluating marine aquaculture practices in other estuaries with OAF or similar anthropogenic structures worldwide.
基金The National Key Research and Development Program of China under contract No.2016YFC0402603the Guangdong Provincial Department of Natural Resources Project under contract No.42090038the Guangdong Provincial Department of Ocean and Fisheries Project under contract No.42090033.
文摘Knowledge of sediment variation processes is essential to understand the evolution mechanism of beach morphology changes.Thus,a field measurement was conducted at the Heisha Beach,located on the west coast of the Zhujiang River(Pearl River)Estuary,to investigate the short-term variation in suspended sediment concentrations(SSCs)and the relationship between the SSC and turbulent kinetic energy,bottom shear stress(BSS),and relative wave height.Based on extreme event analysis results,extreme events have a greater influence on turbulent kinetic energy than SSC.Although a portion of the turbulent kinetic energy dissipates directly into the water column,it plays an important role in suspended sediment motion.Most of the time,the wave-current interaction is strong enough to drive sediment incipience and resuspension.When combined,the wave-current interaction and wave-induced BSSs have a greater influence on suspended sediment transport and SSC variation than current-induced BSS alone.The relative wave height also has a strong correlation with SSC,indicating that the combined effect of water depth and wave height significantly impacts SSC variation.Water depth is mainly controlled by the tide on the beaches;thus,the effects of tides and waves should be conjunctively considered when analyzing the factors influencing SSC.
