Currents in Estuaries
Currents in estuaries are caused primarily by tidal action and river flow. Currents are generally confined to channels but velocities up to several knots can occur. The highest velocities occur in the middle whereas in the bottom and side bank the velocity is lowest. The erosion and deposition in the estuaries are due to currents which is a natural cycle.
However, in estuaries deposition exceeds erosion so there is a net accumulation of silt. During dry part of the year water movement is severely reduced leading to stagnation, reduced oxygen content, formation of algal blooms and incidence of fish kills.