11-13 



Unrestricted river entrances and embayments dominate the 

 estuarine zone and are rather evenly distributed throughout all the 

 regions, with the common type of estuarine system being a coastal 

 embayment with drainage from only the local coastal area. Many 

 of these latter embayments have large marsh areas, but the Middle 

 Atlantic, South Atlantic, and Gulf are the regions in which marshes 

 are the predominant feature in some parts of the estuarine zone. 



The Hater 



The unique nature of water movement and circulation patterns in 

 the estuarine zone are the result of the meeting and mixing of fresh 

 river water and salty ocean water of slightly greater density under 

 the oscillating influence of the tide. There may be additional 

 complicating factors such as temperature and wind action, but the 

 resulting circulation nearly always reflects the interaction of 

 river flow and estuary shape with the tidal flow of the ocean water. 

 General water movement patterns are predictable for each category 

 of estuarine shape. 



It is where moderately large rivers and streams meet the sea that 

 the unique estuarine circulation patterns occur most frequently. 

 Large fresh water flows in well-defined channels tend to slide 

 over the top of the denser sea water without rapid mixing. Water 



movement in such cases exhibits various degrees of stratification. 

 With wider channels, smaller river flows, and greater tidal ranges 



