Which is the world’s largest river? The Nile and the Amazon explained

"Which is the world's largest river?" — the answer usually brings up two names: the Nile of Africa and the Amazon of South America. Both answers are right in their own way, because "largest" can mean length or it can mean the amount of water.

Largest by length: the Nile

The Nile is generally considered the world's longest river — about 6,650 kilometres. It rises in the lake region of East Africa, flows north and empties into the Mediterranean Sea in Egypt. It has two main streams — the White Nile (from the Lake Victoria region) and the Blue Nile (from Lake Tana in Ethiopia) — which meet at Khartoum, the capital of Sudan. The civilisation of ancient Egypt grew up along this river.

Largest by water: the Amazon

No other river in the world carries as much water to the sea as the Amazon. On its own, the Amazon provides about one-fifth of all the water that the world's rivers pour into the oceans. Its drainage basin is also the largest in the world, and the world's largest rainforest spreads across it. In length it comes very close to the Nile, and some scientific measurements have even found it longer than the Nile — which is why the debate still goes on.

Did you know? So much water pours out of the mouth of the Amazon that the sea stays less salty for many kilometres offshore.

The world's major rivers

Measuring a river's length is not easy: where the source is taken to be, how the bends are counted and how the stream changes with the seasons all make the figures differ slightly from source to source.

India's rivers compared with the world

Together, India's Ganga and Brahmaputra form the world's largest delta in the Bay of Bengal — the Sundarbans. By the volume of water it carries, the Brahmaputra is counted among the world's great rivers, especially during the monsoon. The Indus is also one of Asia's long rivers.

Big dams on big rivers

Dams on big rivers help with electricity, irrigation and flood control. The Three Gorges Dam on the Yangtze in China is the world's largest hydroelectric power station by installed capacity. In Egypt, the Aswan High Dam on the Nile (1970) created the huge Lake Nasser, which stopped floods and increased irrigation. Interestingly, not a single bridge crosses the main stream of the Amazon — because of the dense forest and banks that shift with the seasons.

For the exam, in one line

Longest river: the Nile; largest by water and basin: the Amazon; longest in Asia: the Yangtze; longest in India: the Ganga.

Read more: Major rivers of India and where they begin · Class 7 quiz: world geography.