Numerical Study On The Impact Of Sanjiangkou Reclamation In Wenzhou On Coastal Hydrodynamics

Wenzhou Sanjiangkou(Oujiang,Aojiang and Feiyunjiang)is rich in tidal flat and islands.In order to adjust the industrial structure and promote the sustainable development of the local economy and society,Wenzhou City completed a number of estuary reclamation projects from 1996 to 2012.Wenzhou is located on the southeastern coast of China and is hit by typhoons every year.Therefore,considering the hydrodynamic impact of the reclamation project under extreme conditions such as typhoon weather on the Sanjiangkou of Wenzhou,has a reference value for the subsequent development and utilization of this sea area,disaster prevention and mitigation,and it also lays a foundation for the study of the material transport of the reclamation project in this sea area.Based on the tidal current module and the FVCOM-SWAVE module in the FVCOM model,this paper establishes a hydrodynamic model of the waters near the Sanjiangkou of Wenzhou,and uses CCMP wind field as background wind field combining with the Holland wind field as the driving wind field to establish hydrodynamic model under storm surge conditions,and the models were verified separately.Combining satellite remote sensing image data and field observation data,taking the impact of the Wenzhou Sanjiangkou reclamation projects on the shoreline from 1996 to 2012 as the background,taking into account the impact of the estuary runoff,etc.,the numerical simulation and analysis of the impact of Wenzhou Sanjiangkou reclamation(1996 to 2012))on tidal field in the nearby sea area were finished;Taking the typhoon “Fung-wong” passing through the area as background,the impact of the Sanjiangkou reclamation in Wenzhou(1996-2012)on the storm surge in the nearby sea area during the typhoon was numerically analyzed;On this basis,considering the coupling effects of typhoon and waves,the effects of the reclamation of Sanjiangkou in Wenzhou(1996-2012)on the coupled motion of typhoon waves and storm surges in the nearby sea area during the typhoon were numerically analyzed.The research results show that the Wenzhou Sanjiangkou reclamation project has little effect on the tidal level and tidal current of the sea area.The main affected area is concentrated near the estuary reclamation project,and the flow velocity only increases slightly on the north side of the Oujiang River estuary,and the change of tidal level and velocity at other estuaries is not obvious.In typhoon weather,extreme conditions increase the complexity and instability of tidal levels and tidal currents near the reclamation project.Overall,the flow velocity and tidal level have increased compared with normal conditions,but the increase of value is smaller.The estuary velocity and tidal level in the calculation domain were affected by typhoon.The reclamation caused a difference in tidal levels on the north and south sides of the Lingni Embankment,a large increase in water near the estuary,and a rise and fall in the tidal level near the estuary.Under the influence of storm surges,the velocity of most characteristic points at the rush moment in the Sanjiangkou sea area increased more than before the reclamation,and the velocity of most characteristic points at the ebb moment decreased,which may be related to the combined effects of river flow,typhoon wind direction and tidal current direction.The influence of typhoon waves and storm surges,typhoon waves and astronomical tides on the estuary has caused a significant increase in the characteristic point velocity on the north side of the Oujiang Estuary,with a maximum increase of more than 400%,which may be caused by the reclamation project on the north side of the estuary,which narrows the river outlet and causes the increase of the flow rate.The velocity of characteristic points on the southern side of the Oujiang River Estuary decreased at the ebb moment after the reclamation,which may be due to the reclamation of shoal in Oujiang River Estuary and the construction of the Lingni Embankment,which prevented the flow of water that originally flowed out of the northern side of the estuary to the southern side,and under the influence of typhoon waves and storm surges,the flow velocities of the Feiyun River and Aojiang River estuary before and after reclamation decreased significantly at the ebb moment,with a decrease of between 30% and 80%.