A small river meeting a larger river.
Tributary
Where the river flows into the sea.
Mouth
Where a river begins
Source
The total area drained by a river & its tributaries.
Drainage Basin
A: The natural path or trench that a river flows through. It has the banks on the sides and the bed on the bottom. B: Water flowing in stream and river channels.
A. River Channel B. Channel Flow
The part of the river mouth which is tidal.
Estuary
The high ground that separates two drainage basins.
Watershed