Stream velocity does it have anything to do with discharge of stream or stream elevation?

The velocity increases too.

Stream discharge is a product of the velocity and the area of the stream (velocity x width x depth), and has units of volume per time (e.g. cubic feet per second, cubic meter per day, etc). Stream...

An increase in gradient will generally increase stream velocity.

a streams discharge is the excess water from a storm or melted snow.

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