Drainage basins and the source of a river
The source of ariver
The source of the river is where the river originates from. It is in the upper course of the long profile.
A video on the source of the River Severn –
http://www.bbc.co.uk/learningzone/clips/the-source-of-the-river-thames/12571.html
A drainage basin
A drainage basin is the area from which a river gets it water. The watershed represents the area from which the river gets it water from. If rain falls outside of this watershed it will run into another river system. The source of the river is where the river originates from. A tributary is a smaller river which joins the main river channel. A confluence is the point where two rivers meet. The mouth of the river is where the end of a river meets the sea.