东海大桥邻近海域沉积动力环境变化OA北大核心CSTPCD

[Objective]The East China Sea Bridge is located in the important passage between Hangzhou Bay and the Yangtze River Estuary where the exchange of water and suspended sediment occurs,which has a significant im-pact on the distribution and transportation of the suspended sediment in the adjacent area.Therefore,the variation characteristics of suspended sediment concentration(SSC)on both sides of the East China Sea Bridge for the tidal cy-cle,seasonal,and interannual scales are studied.[Methods]Based on 26 days of high-quality Geostationary Ocean Color Imager(GOCI)images with 8 continuous tidal hour per day from 2011 to 2020,the inversion equation was es-tablished to transfer remote sensing reflectance to SSC in the adjacent waters around the East China Sea Bridge.In addition,combined with the ideal numerical model and the observation data of seabed sediment,the influence of the East China Sea Bridge on the changes of suspended sediment and seabed sediment distribution at different time scales was studied.[Results]The results show that the SSC on both sides of the East China Sea Bridge presents an obvious gradient distribution,with the higher value on the lee side and lower value on the upstream face of the bridge during both the flood and ebb periods.The SSC difference reaches 300%,which is related to the vertical movement caused by the lower water level on the lee side of the bridge and strengthened disturbance induced by the vortex behind the piers.During the ebb and flood maximum times,the difference in SSC between the two sides of the bridge is the largest,and the difference between the two sides at the flood slack and fall is the smallest.During the ebb period,the difference of SSC on both sides of the bridge is significantly greater than that of high tide.The gradient distribution of SSC on the two sides of the bridge is not significantly different during the ebb and flood periods in different seasons,but the concentration difference is different.The difference of SSC on both sides of the bridge in winter is less than 300 mg/L,which is less than the value in summer that reaches 500 mg/L.Spring is the transitional season,and the difference of SSC on both sides of the bridge in spring is between winter and summer.From the changes over the years,the SSC gradient on both sides of the East China Sea Bridge has little changed.Comparing the grain size chang-es of seabed sediments near the bridge after 11 years of bridge construction,the seabed sediments in the adjacent waters become finer,which may be related to the weakening of the current velocity due to the water blockage effect by the bridge.[Conclusion]This study concludes SSC gradient distribution between the two sides of the bridge with higher value in the leeside while lower value in the upstream face,which does not vary seasonally or annually.This study is of great significance to improve the research on the impact of cross sea bridges on the marine environment at different time scales.