Formation of Equilibrium Beach Profile of the Abandoned Yellow River Delta Coast in North Jiangsu

The abandoned Yellow River Delta coast is a typical erodible silty and muddy coast in China. The paper analyses the marine dynamic characteristics and the mechanism of beach erosion of this area. Analysis and calculation show that in this sea area wave and tidal current action should be considered. Based on the above analysis, an equilibrium beach profile calculation model is developed, in which the wave-current interaction is considered while sediment supply and sediment re-deposition are neglected. The model consists of four parts: (1) calculation of wave parameters, (2) calculation of velocity due to wave-current interaction at different water depth, (3) calculation of friction velocity and shear stress at different water depths, and (4) calculation of the amount of sediment erosion, erosion intensity and variation of beach profile. Calculated results are in good agreement with observed data. Finally, the evolution tendency is discussed and the equilibrium beach profile of this coast is calculated. B

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta, northern Jiangsu

The delta evolution and erosion process of the abandoned Yellow River Delta （AYRD） have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model, In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance （De） with the average range value （Ao） of grain size parameter. Filtering method （removing data that not at a sampling station） is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta （AS） is better than that in the northern part of the abandoned Yellow River Delta （AN）. Sediment in the area is found to be anisotropy at the northeast-southeast direc- tion. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between Do, Ao, sediment transport and delta evolution shows a close link between Do and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.

Effects of Coastline Changes on Tide System of Yellow Sea off Jiangsu Coast,China

On the basis of historical documents, this paper studies the evolutionary processes of the Jiangsu coast and re-estahhshes the positions of the shoreline in different periods. The East China Sea and the Yellow Sea mathematical models are applied to simulate and analyze the large-scale tidal waves changes under the influence of the coastal change in Jiangsu since 1855 when the Yellow River changed its lower course into the Bohai Sea. Results from this study can be summa- rized in the following aspects： （1） the coastline change strongly affects tidal waves in the region. Generally, the tidal amphtude decreases when the coastline changes in the north coast area of the abandoned Yellow River Delta, whilst increases in the south of this region. The maximum variation of tidal amphtude takes place near the Radial Sandbank. （2） Following the erosion of the abandoned Yellow River Delta in the past century, the non-tidal points of M2 and K1 partial tides move to southwest gradually. （3） During the early 20th century, with the coastline changing, tidal range decreased 30 - 60 cm. From the abandoned Yellow River mouth to the Lvsi Port, the maximum increase of tidal range can exceed nearly 150 cm. From the early 20th century to the early 21st century, the tidal range increases by 20- 50 cm outside the Radial Sandbank. Whereas, the tidal range reduced near the abandoned Yellow River mouth by 30 ~ 50 cm.