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Information on Rivers

River

From Wikipedia, the free encyclopedia

A river is a natural waterway, which moves water across the landscape from higher to lower

elevations, and is an important component of the water cycle. The water within a river is
generally from precipitation through surface runoff, groundwater recharge (as seen at base-
flow conditions / during periods of lack of precipitation) and release of stored water in
natural reservoirs, such as a glacier.

Origins of river water

A river may have its source in a spring, lake, from damp, boggy landscapes where the soil is
waterlogged, from glacial melt, or from surface runoff of precipitation. Almost all rivers are
joined by other rivers and streams termed tributaries the highest of which are known as
headwaters. Water may also come from groundwater sources. Throughout the course of the

river, the total volume transported downstream will often be a combination of the free water
flow together with a substantial contribution flowing through sub-surface rocks and gravels
that underlie the river and its floodplain (called the hyporheic zone). For many rivers in
large valleys, this unseen component of flow may greatly exceed the visible flow.

The beginning of a mountain river (Reichenbach in Grosse
Scheidegg)

From their source, all rivers flow downhill, typically terminating in
the sea or in a lake, through a confluence. In arid areas rivers sometimes end by losing

water to evaporation. River water may also infiltrate into the soil or pervious rock, where it
becomes groundwater. Excessive abstraction of water for use in industry, irrigation, etc., can
also cause a river to dry before reaching its natural terminus.

The mouth, or lower end, of a river is known by hydrologists as its base level.

The area drained by a river and its tributaries is called catchment, catchment basin,
drainage basin or watershed. The term "watershed" is also used to mean a boundary
between catchments, which is also called a water divide, or in some cases, continental divide.

(God's Amazing Landscapes) 14