A natural stream channel that branches from a trunk stream which it may or may not rejoin. It occurs typically on the surface of an alluvial fan or delta, where it may be part of a complex, fan-shaped network that distributes the discharge and sediment load of the main channel among many small distributary channels between which a variable assemblage of bays, lakes, tidal flats, or marshes may exist. The larger distributory channels show crevasse splays and levées. See also anabranching channel.