A tributary,[1] or an affluent,[2] is a stream or river that flows into a larger stream (main stem or "parent"), river, or a lake.[3] A tributary does not flow directly into a sea or ocean.[4] 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.
The Irtysh is a chief tributary of the Ob river and is also the longest tributary river in the world with a length of 4,248 km (2,640 mi). The Madeira River is the largest tributary river by volume in the world with an average discharge of 31,200 m3/s (1.1 million cu ft/s).
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.[5] Distributaries are most often found in river deltas.
- ^ "tributary". PhysicalGeography.net, Michael Pidwirny & Scott Jones, 2009. Viewed 17 September 2012.
- ^ "affluent". The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. Viewed 30 September 2008.
- ^ "Definition of TRIBUTARY". Merriam-Webster.
- ^ Krebs, Robert E. (2003). The Basics of Earth Science. Greenwood Publishing Group. ISBN 978-0-313-31930-3.
- ^ "opposite to a tributary". PhysicalGeography.net, Michael Pidwirny & Scott Jones, 2009. Viewed 17 September 2012.