river's coast

A river's edge refers to a narrower strip, IMO.

Rivers do not have coasts. Nor do lakes. Coast = the shore of a sea or ocean.

AnonymousA river's edge refers to a narrower strip, IMO.

I don't know what is "narrower strip".

Anon means that the edge of the river-- the part that appears different from the surrounding land and is affected by the water's rise and fall-- is not normally as wide as an ocean beach or coast. It is a 'strip' because it is long and narrow, running beside the river.

The river bank.

Thank you friends.

Mister MicawberAnon means that the edge of the river-- the part that appears different from the surrounding land and is affected by the water's rise and fall-- is not normally as wide as an ocean beach or coast. It is a 'strip' because it is long and narrow, running beside the river.

Could you tell me the "running" refers to

Colloquial usage - it does not literally mean running, but that there is a strip of land along the length of the river.

This is one of those English idioms that you will have to take on face value. It is an expression that is much used.