Increase in Suspended Sediment Contents by a Storm Surge in Southern Bohai Sea, China

Abstract

Most of the existing results were related to the impact of land storms on sediment, and few explained the impact of storms on sediment movement and its formation law from the mechanism. At present, the research on the impact of storm on sediment suspension on the North Bank of Longkou City in the south of Bohai Sea was not clear. Therefore, this study aimed to explore the formation and mechanism of storm on suspended sediment from the perspective of hydrodynamic characteristics and sediment distribution by monitoring the impact of storm on sediment suspension in the south of Bohai Sea. A storm with wind speeds of 4.5–13.5 m/s occurred in the coastal area of the north side of Longkou City located in Southern Bohai Sea in April, 2015. Suspended sediment samples were obtained using automatic samplers, and the results showed that the suspended sediment content was 7.8 mg/L under normal weather conditions, which reached 121.2 mg/L at the highest during the storm event. Waves and tides were synchronously observed by acoustic Doppler current meter. Wave height was more closely correlated with wind speed when the wind veered to north, and the maximum wave height was 243 cm. The reciprocating motion of the current at the sampling site was strong, with the maximum current speed of 43.8 cm/s and a water depth of 10 m. The results of laser analysis showed that the bottom sediments were composed of 92% sand and 8% silt, with a medium diameter of 0.102 mm. From the experimental observation and result analysis, it was known that the strong dynamic process during storm surge led to the movement of sediment surface and the resuspension of sediment.