Confluence

n. flowing together of two or more streams; coming together of people or things, assemblage

Confluence, in geography, describes the meeting of two or more bodies of water. It usually refers to the point where a tributary joins a more major river, called the mainstem, when that major river is also the highest order stream in the drainage basin. The German city name Koblenz indicates, in Germanicized form, its site at the confluence of the Rhine and the Mosel.
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Noun
1. a place where things merge or flow together (especially rivers); "Pittsburgh is located at the confluence of the Allegheny and Monongahela rivers"
(synonym) meeting
(hypernym) geographic point, geographical point
(classification) river
2. a flowing together
(synonym) conflux, merging
(hypernym) blend, blending
3. a coming together of people
(synonym) concourse
(hypernym) merging, meeting, coming together

n. confluence

(n.)
The act of flowing together; the meeting or junction of two or more streams; the place of meeting.
  

(n.)
Any running together of separate streams or currents; the act of meeting and crowding in a place; hence, a crowd; a concourse; an assemblage.