Rivers

A river is a natural stream of freshwater with significant volume when compared to the volume of its smaller tributaries. Conveying surface water run-off on land, rivers are normally the main channels or largest tributaries of drainage systems. Typical rivers begin with a flow from headwater areas made up of small tributaries, such as springs. They then travel in meandering paths at various speeds; finally, they discharge into desert basins, into major lakes, or most likely, into oceans.

Sixteen of the world's largest rivers account for close to half of the world's river flow. By far, the largest river is the Amazon River, running 3,900 mi (6,275 km) long. Discharging an average of four million cubic feet (112,000 cu m) of water each second, the Amazon River alone accounts for 20% of the water discharged each year by Earth's rivers.