Discover

(Redirected from Water divide)

A 'drainage divide', 'water divide', or simply 'divide' is the separation between neighbouring drainage basins (catchments). In hilly country, the divide lies along topographical peaks and ridges, but in flat country or on a high plateau (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 country or continent.
Drainage divides are important geographical, and often also political, boundaries. Roads and rail tracks often follow divides to minimise grades (or gradients) and the need for bridges.
A divide is also known as:

★ traditionally, a 'watershed'; in North America this term is old-fashioned or nontechnical, since it usually refers to the drainage basin;

★ a 'water parting';

★ a 'height of land' (in Canada).

Contents

Types of drainage divide

Types of drainage divide

Drainage 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 drainage 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 drainage divide — The waters part but eventually meet again at a river confluence (example: the Mississippi and Missouri divide)
Drainage 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.