Abstract

Based on the sediment transport theory and water flow energy equilibrium theory, an expression of semi-tidal period averaged suspended sediment concentration in estuaries is developed for different conditions of water flow, and a case study is conducted for the Yangtze River Estuary. The separation of sediment concentration is helpful to the interpretation of the characteristics of erosion and siltation in estuaries by means of sediment load transported by water flow and suspended sediment from the riverbed. For the Yangtze River Estuary, load transported is the main form of sediment transport and the possibility of silting is large in the flood season, while suspension of sediment from the riverbed is predominant and riverbed erosion is serious in the dry season, i.e. “siltation in the flood season and erosion in the dry season” in the Yangtze River Estuary. The results show that suspended sediment concentration in estuaries consists of sediment load transported by water flow and suspended from the riverbed, and the concentration is also influenced by other dynamical factors such as wind, wave, etc. Besides, the present expression of sediment concentration has laid a foundation for calculating the semi-tidal period averaged sediment-carrying capability for estuaries.

Keywords: tidal estuary, flow energy, suspended sediment concentration, correlation analysis