RECENT ACCUMULATION RATES IN THE COASTAL AREA BETWEEN CHANGJIANG ESTUARY AND HANGZHOU BAY

摘要

Total 15 sediment cores were collected in the coastal area between Changjiang estuary and Hangzhou bay. Using the ~(210)Pb and ~(137)Cs dating methods, the recent accumulation rates for the cores are estimated. The results show the obvious spatial distribution of deposition. To the east of the Shijiao Channel, less Changjiang's sediment input leads to the lower accumulation rates around Maan Islands. To the west of the Channel, the coastal area is the main passage of the Changjiang's sediment southward diffusion. In the middle shoal area of Hangzhou bay, the accumulation rate reaches 3 cm·yr~(-1) because of the sediment transportation effects of tidal front. In the water area of the Yangshan harbor, the area deeper than 20m has been eroded while the shallow area is slowly accumulated with 0.3 cm·a~(-1)-1.6cm·a~(-1) rate. At the Majishan harbor, being located at a muddy slope along the typical tidal channel, the accumulation process is unstable. Although the normal accumulation rate is 0.7 cm·yr~(-1)-3.4 cm·yr~(-1), rapid accumulation and slipping of subbottom layer also frequently occur.