出典:Wiktionary
出典:『Wiktionary』 (2017/04/17 15:36 UTC 版)
出典:Wikipedia
出典:『Wikipedia』 (2011/07/01 16:04 UTC 版)
In relation to hydrology, a main stem is "the primary downstream segment of a river, as contrasted to its tributaries". Another common term for the main stem, the final large channel of a riverine system, is the trunk. Water enters the main stem from the river's drainage basin, the land area through which the main stem and its tributaries flow. A drainage basin may also be referred to as a watershed or catchment.