SURFACE SEDIMENT DISTRIBUTION PATTERN AND TRANSPORT TRENDS OF SANDY BEACH NEAR YUANTUOJIAO POINT, ESTUARY OF THE NORTH BRANCH OF CHANGJIANG RIVER

Based on the grain size analysis of the surface sediments sampled in August, 2011 at the sandy beach close to the Yuantuojiao Point, the sediments distribution pattern and sands transportation trend were discussed in this paper. The Yuantuojiao Point is located at the transition site between the north branch of the Yangtze River and the Jiangsu coast, and experienced rapid sedimentation in the past decades. The grain size data, such as the mean grain size,sorting coefficient, skewness and kurtosis, were analyzed. The results showed that the sediments were mainly composed of well sorted fine sand with positive skewness. The grain size data was processed using the Gao-Collins model for the purpose of grain size trend analysis. It is found that the sandy beach sediments were transported from sea to the shore in general and the sediment transport trend is strongly influenced by topography. In front of the dike, sediments are transported to the sea. And through the analysis of a series of remote sensing images of the bar near the Yuantuojiao Point, we found that the extending direction of the bar is parallel to the coastline. There is a spit developing in the front of the bar, extending to the southeast.