Mechanism of Silt-mud Couplet of Mud Tidal Flat and Discrimination Criteria of Storm Surge Sedimentation in the Middle Jiangsu Province

Key words: 
• tidal couplet /
• mechanism /
• storm surge /
• discrimination criteria /
• middle Jiangsu province

Abstract: Field observation on the formation and development process of silt-mud couplets is carried out on tidal flat of the middle Jiangsu province. Combined the observation result with the calculation of sedimentation quantity and the analysis of grain-size and roundness of sedimentary particles, the mechanism of silt-mud couplets is revealed in this area. One thin silt-mud couplet with the thickness of millimeters is formed during a flood-ebb tidal cycle, and one thick couplet with the thickness of centimeters is formed during a spring-neap tidal cycle.
In addition to the research on the formation of silt-mud couplets, the field observation on the tidal flat is carried out before and after the storm surge for typhoon No. 9711. The result shows that even during storm surge period, high tidal flat can still be in sedimentation over some places, no erosion occurred. Compared with the normal tidal flat sedimentation, the storm sedimentation has the characteristics of coarse particle, bad sorting, relatively high roundness, obviously graded bedding, typical parallel bedding, cross bedding.