An estuary. is a partly enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments.
The features of an estuary are determined by a region's geology, and influenced by physical, chemical, and climatic conditions.For example, movements in the Earths crust elevate or lower the coastline, changing the amount of seawater that enters an estuary from the ocean.he amounts of seawater and fresh water flowing into an estuary are never constant. The quantity of seawater in an estuary changes with the changing tides, and the quantity of fresh water flowing into an estuary increases and decreases with rainfall and snowmelt.
An estuary is a sheltered, enclosed or semi-enclosed body of water where fresh and salt water mix. Estuaries generally have large sand and mud flats which are exposed at low tide and covered at high tide.There can be several estuaries within a harbour.here fresh and salt water mix. The mixing of fresh water and sea water is an important and distinct feature of the estuary. Fresh water, being lighter or less dense than salt water, will flow above the heavier sea water. In estuaries where large amounts of freshwater are discharged, a salt wedge is formed.