Study On The Dynamic Characteristics Of The Tidal Flats In The South Yellow Sea

Radial Sand Ridges Area in the South Yellow Sea with muddy coast is in the middle part of Jiangsu coastal area.The morphodynamic process is complex and coastal evolution changed greatly.The research of coastal evolution is important to the protection of ocean resource,the construction of ocean engineering and the management of coastal zone.On the basis of collecting previous data in Radial Sand Ridges Area,combined with remote sensing,GIS and DSAS techniques,this paper analyzed the change of tidal flat area above Om and coastal evolution from 1995 to 2015.The paper also discussed different driving force of the coastal evolution from hydrological dynamics,sediment source and so on.The paper estimated the mean high water spring,mean low water spring and 0m through tide correction and waterline techniques.The results showed that the coast slope is stable and sharping from 1995-2015.The results indicate that the whole artificial shoreline showed a trend of accretion and slowed down gradually during the study process.In order to meet the requirements of social and economic development,massive reclamation activities have been carried out in this area.As a result,the reclamation elevation is approaching the mean low water spring and under the mean high water spring.The mean low water spring showed a trend of erosion from the Sheyang River Estuary to the Doulong port and advanced to the southern part during 2002-2009.This coast transferred from silting to erosion.The 0m showed a trend of erosion in the whole area,especially in the subtidal,advanced in 1995-2009 and slowed down during 2009-2015.During the study period,the tidal flat area above 0m changed a little from 1995-2015.From the aspect of time frame and the space distribution of coast,most coast showed a trend of accretion in 1995-2002.However,the most coast showed a trend of erosion from 2009-2015.Therefore,the year of 2002 is most likely the time turning point of coastal erosion.The northern part of Zhugang port and the southern part of Dayang port both showed the trend of erosion in 0m and mean low water spring.Addtionally,the southern part of Zhugang port to Xyangkou coast showed a trend of accretion.In the whole coast the accretion and erosion velocity both decreased yearly.Xiaoyangkou coast to Yaowanggang port showed a trend of accretion and erosion obviously,followed to new banlance of accretion and erosion.Therefore,Zhugang port nearby may be a new spatial turing point of the study area.The analysis of coastal erosion mechanisms showed that the main driving force was the sediment source,ocean power and other natural factors in the northern part of radial sandbanks,inner part and the middle part.Besides this,the aquaculture,port construction and other human activities also play an important role in the coastal evolution in the southern part of radial sandbanks.