Abstract

The major mechanism of regulation of sediment concentration distribution at the tidal river mouths is the estuary circulation. Resulting movement of water upstream near the bottom, the high velocities of flood tidal currents, and increased turbulence result in occurrence of the zone of turbidity maximum (so-called “silty plug” and “fluid mud”). In this place, the concentration of suspended sediments is higher, than in river and sea waters. The presence of turbidity maximum is typical of estuaries of the Mezen River in Russia, and the Gironde, Seine, Loire rivers in France and leads to the accumulation of suspended sediments and to the deterioration of navigation conditions in estuaries.

Keywords: The tidal river mouths, estuary circulation, sediment, turbidity maximum.