Author(s): Liqin Zuo; Yongjun Lu; Rongyao Ji
Linked Author(s): Yongjun Lu
Keywords: Mouth bar; Siltation; Muddy coast; Strong-tidal estuary; Wave-induced sedimentation; Aojiang estuary
Abstract: Aojiang estuary, located at west side of East China Sea, is a typical strong-tidal and muddy estuary, with mouth bars at its entrance. This paper focuses on the back silting in its estuarine mouth bar. Data analysis of measured back silting in a trial tunnel and a 2D mathematical model for sediment transport under co-action of waves and tidal currents were used. Tidal currents from upstream diffuse at the entrance as the river mouth widens, thus deposition happens. Meanwhile, the maximum turbidity zone provides sufficient sediment sources. These are the main causes of Aojiang mouth bar ’s formation. Results showed that, the back silting in Aojiang estuary mouth bar is mainly influenced by wind-waves. The sediment in surrounding beach which is stirred and carried during windy days is the main source of back siltation. The main back silting after dredging happens in representative wave days, sudden siltation often happens in typhoon days and back silting is relatively less in current days. After storm events, the siltation depth decreases. Preliminary analysis showed that this phenomenon is caused by fluid mud density compacting. Compared with other muddy coasts such as Tianjing Port, it could be concluded that, strong hydrodynamic conditions and abundant sediment source are the main reasons for sudden siltation in Aojiang estuary. In addition, regulation methods are discussed for mouth bar channel of this type.
Year: 2013