Sediment transport in response to changes in river discharge and tidal mixing in a funnel-shaped micro-tidal estuary

• We investigate sediment transport in the Huangmaohai Estuary, Pearl River Delta, China.
• The sediment dynamics is largely controlled by tidal asymmetry.
• The sediment transport is landward in the channel and seaward on the shoals.
• Sediment is imported from the East Opening and exported through the Middle Opening.
• Enhanced tidal mixing or increased river discharge result in a predominantly seaward transport.

Huangmaohai Estuary is a micro-tidal funnel-shaped estuary, located along the southwestern side of the Pearl River Delta complex. Variations of sediment transport patterns under different conditions of river discharge and tidal mixing are investigated by using field measurements and data analysis during both dry and wet seasons, respectively. The intratidal variation of sediment dynamics is largely controlled by the tidal asymmetry. The typical pattern of 25-hour mean sediment transport during the dry season is that the transport is landward in the channel and seaward on the shoals. A bifurcation pathway of sediment transport shows that sediments are imported from the East Opening and exported through the Middle Opening. However, this pattern can be altered by mixing processes and river discharge. Enhanced mixing or increased discharge can result in a predominantly seaward transport. Conversely, weak mixing can result in an emphatic landward transport. In general, the sediment transport is closely associated with the morphological evolution in the estuary.