Water divide
|
Main European water divides |
A
water divide (also known in Commonwealth usage as a
watershed) is the separation between neighbouring
drainage basins, and lies along
topographical peaks and
ridges. Water divides are important
geographical, and often also
political,
boundaries. A water divide is also sometimes called a
water parting or a
height of land (in North America, especially Canada).
Water divides can be grouped in three types:
*
Continental divide — A divide in which the waters on each side flow to different oceans (example: the
Nile and
Congo divide)
* Major water divide — The waters on each side of the divide never meet again, but do flow into the same ocean (example: the divide between the
Yellow River basin and the
Yangtze)
* Minor water divide — The waters part but eventually meet again at a river confluence (example: the
Mississippi and
Missouri divide)
Water divides are a hindrance to
river navigation. In pre-industrial times water divides were crossed at
portages. Later
canals were built to connect the adjoining drainage basins.
