Influence Of Reclamation Activities On The Shoreline And Hydrodynamic Environment Of Bohai Bay

Land space for industrialization and urbanization in China is relatively scarce,which has restricted and limited the advancement of national economic construction and the improvement quality of life.As a result,coastal reclamation has become an effective way to ease the contradiction between supply and demand of land.Since the21st century,coastal reclamation are greatly improved with faster speed and larger scale.Taking Bohai Bay as an example,from 2000 to 2015,the coastal area has been reduced by 1178km~2 because of reclamation activities.Such a large-scale human activities will inevitably have an impact on the marine environment.In order to study the influence of reclamation on the hydrodynamic environment of Bohai Bay,this paper analyzes the temporal and spatial variation of the coastline in the past 30 years by using satellite remote sensing image and chart data.The changes of the tidal volume are calculated.The dynamic changes of the tidal current were simulated by using the MIKE21 hydrodynamic model.Besides,the effect of the reclamation on the marine environment was discussed based on the data and the simulation results.The results show that the period of shoreline change in Bohai Bay can be divided into two part:1984 to 2005 and 2005 to 2016.In the first 20 years,the main reclamation was around coastal intertidal zone,which was used for fishing and salt production.The shoreline grew offshore in a small area.The more obvious change was the disappearance of large tracts in the south part.In the past 10 years,the newly increased land area of Bohai Bay mainly extended to the sea area due to the construction of large ports,Artificial shoreline grew rapidly.Compared with the year2000,the tidal volume in the Bohai Bay decreased by 6%in 2015,and the correlation between sea area and tidal level reduced too.The influence of reclamation on the hydrodynamic characteristics was not significant,while the change of tide and current around the engineering area was more obvious.The current speed of fluctuations of the whole sea area decreased slightly,and the decreased amount of velocity and area during flood peak were larger than that during minimum flood.The velocity of the nearshore area between 0 to-6 m isobaths was reduced while the change of current speed of fluctuations outside the area of-6 m isobaric was not obvious.