Editing Tributary (section)

{{Short description|Stream or river that flows into a main stem river or lake}}
{{About|a lesser flow of water|other uses|Tributary (disambiguation)}}
{{Use dmy dates|date=October 2024}}
[[File:Mouth of Nam Khan.JPG|thumb|upright=1.1|[[Nam Khan]] flows into the [[Mekong]] at [[Luang Prabang]] in [[Laos]].]]
A '''tributary''',<ref>[http://www.physicalgeography.net/physgeoglos/t.html "tributary"]. PhysicalGeography.net, Michael Pidwirny & Scott Jones, 2009. Viewed 17 September 2012.</ref> or an '''''affluent''''',<ref>[http://dictionary.reference.com/browse/affluent "affluent"]. The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. Viewed 30 September 2008.</ref> is a [[stream]] or [[river]] that flows into a larger stream (''[[main stem]]'' or ''"parent"''), river, or a [[lake]].<ref>{{cite dictionary|url=https://www.merriam-webster.com/dictionary/tributary|title=Definition of TRIBUTARY|dictionary=[[Merriam-Webster]]}}</ref> A tributary does not flow directly into a [[sea]] or [[ocean]].<ref>{{Cite book|url=https://books.google.com/books?id=-4ndyH7u6T0C&pg=PA179|title=The Basics of Earth Science|last=Krebs|first=Robert E.|date=2003|publisher=Greenwood Publishing Group|isbn=978-0-313-31930-3}}</ref> Tributaries, and the main stem river into which they flow, drain the surrounding [[drainage basin]] of its surface water and [[groundwater]], leading the water out into an ocean, another river, or into an [[endorheic basin]].

The [[Irtysh]] is a chief tributary of the [[Ob (river)|Ob]] river and is also the longest tributary river in the world with a length of {{cvt|4248|km}}.
The [[Madeira River]] is the largest tributary river by volume in the world with an average discharge of {{convert|31200|m3/s|e6ft3/s|abbr=unit|1}}.

A [[confluence]], where two or more [[bodies of water]] meet, usually refers to the joining of tributaries.

The opposite to a tributary is a [[distributary]], a river or stream that branches off from and flows away from the main stream.<ref>[http://www.physicalgeography.net/physgeoglos/t.html "opposite to a tributary"]. PhysicalGeography.net, Michael Pidwirny & Scott Jones, 2009. Viewed 17 September 2012.</ref> Distributaries are most often found in [[river delta]]s.