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 (such as
ridgeways) and
rail tracks often follow divides to minimise
grades (gradients) and the need for bridges.
A divide is also known as
Drainage divides can be grouped in three types
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.
