Estuary Circulation Patterns

Patterns of estuarine circulation play an important role in sedimentation within the estuary and the distribution of different ecosystems in the estuary. Fundamental control on the types of circulation patterns can be linked to the relative relationships of freshwater input, the tidal range, velocity and direction of winds, and currents created by waves. Each of these is capable of creating currents within the estuary and thus control how freshwater and saltwater interact in the estuary and where sediment can accumulate within an estuary. For example, during periods of low river inflow to an estuary, wind-driven saltwater may move farther into an estuary than it would during high river discharge into the estuary. During intervals of high freshwater run off, freshwater and sediment may extend well into the estuary and lead to sedimentation near the mouth of the estuary in a location where sedimentation by rivers is typically low.