出典:Wikipedia
出典:『Wikipedia』 (2011/06/12 22:40 UTC 版)
A drainage divide, water divide, divide or (outside North America) watershed is the line separating neighbouring drainage basins (catchments). In hilly country, the divide lies along topographical peaks and ridges, and may be in the form of a single range of hills or mountains (known as a Dividing range), but in flat country (especially where the ground is marshy) the divide may be invisible – just a more or less notional line on the ground on either side of which falling raindrops will start a journey to different rivers, and even to different sides of a region or continent.