GEOGRAPHICAL RESEARCH ›› 2010, Vol. 29 ›› Issue (5): 909-916.doi: 10.11821/yj2010050015

• Earth Surface Processes • Previous Articles     Next Articles

Recent morphological changes of tidal flat at Yuantuojiao Point,estuary of the north branch of the Yangtze River

ZHANG Zhen-ke, XIE Li, CONG Ning, LI Ying, WANG Xiu-ling, HE Hua-chun   

  1. School of Geographic and Oceanographic Sciences, MOE Key Lab. of Coast &|Island Development, Nanjing University, Nanjing 210093, China
  • Received:2009-04-17 Revised:2009-09-19 Online:2010-05-20 Published:2010-05-20

Abstract:

Yuantuojiao Point is located at intersecting point of the coastal lines of the north branch of the Yangtze River and the south Yellow Sea. The specific geographic location with the salt marsh environment (tidal flat) and the complexity of regional morphological dynamics that determined the tidal flat at Yuantuojiao Point had the sensitive response to the environmental changes. Because of the rapid sea reclamation, the coastline has shifted eastward over 6 km in the past 40 years. Based on the field investigation, grain size analysis of the surface sediments in the tidal flat and the 137 Cs dating analysis of the short core samples, the tidal flat at Yuantuojiao Point has experienced the extensive siltation since 2006. The annual average sedimentation rate was about 2.3 cm/a from 1963 to 2006 according to the 137 Cs dating analysis. From 2006 to 2008 the observed sedimentation rate was more than 4.0 cm/a in the salt marsh region and even high sedimentation rate occurred on the muddy tidal flat. The front cliff of the salt marsh retreated under the storm surge condition compounding with the increasing sedimentation in the muddy tidal flat, which resulted in the extinction of the cliff. The recent morphological changes of the tidal flat at Yuangtuojiao Point was the response to the sea reclamation, storm surge and the tide process. Both the salt marsh and the muddy tidal flat that experienced the accelerating sedimentation are the main characteristics of the morphological changes of the tidal flat at Yuantuojiao Point.

Key words: north branch of the Yangtze River, estuary, siltation, tidal flat, morphological changes, Yuantuojiao Point