Please telll me the answer.?

Question

How the salt content of an estuary changes constantly.

Answer 1

An estuary is the area "near a river mouth in which the fresh water of the river mixes with the salt water of the sea." http://www.deh.gov.au/water/rivers/nrhp/estuarine/appendix4.html

Since the volume of flow of fresh water from a river varies, and since the salt water tides move in and out, the salt content in an estuary is variable.