Question

River system is made up of a river and its what

Answer 1

A river and all its tributaries make up a river system. Tributaries are streams and smaller rivers that feed into a main river.

Answer 2

It's a drainage basin or watershed

Step-by-step explanation:

A river and it's tributaries make up a river system.

A river watershed includes the river, all its tributaries, and any groundwater resources in the area.