Geography
What is a river?
Quick answer
A river is a large stream of fresh water that flows downhill from its source, often in hills or mountains, to its mouth at a sea, lake or another river.
In one sentence
A river is a large, natural stream of fresh water that flows downhill from its source, often in hills or mountains, to its mouth at a sea, a lake or another river.
Explained
Rivers are part of the water cycle. Rain and melting snow fall on high ground, and gravity pulls the water downhill. Tiny streams join up and grow into a river.
Parts of a river
| Word | Meaning |
|---|---|
| source | where the river starts, such as a spring or melting snow |
| mouth | where it ends, at a sea, a lake or a bigger river |
| tributary | a smaller river that joins a bigger one |
| confluence | the place where two rivers meet |
| river basin | all the land that drains into one river |
How a river changes on its way
- Upper course: near the source, the river is usually narrow, fast and steep. It cuts V-shaped valleys and sometimes forms waterfalls.
- Middle course: the land is flatter, so the river is wider and slower. It swings in big loops called meanders.
- Lower course: near the mouth, the river may drop the mud it carries and build a fan of new land called a delta, or widen into a funnel where it meets the tide, called an estuary.
Which river is longest?
Most books say the Nile (about 6,650 km, or 4,130 miles), with the Amazon (about 6,400 km, or 4,000 miles) close behind. The answer depends on where you decide each river begins, and some measurements make the Amazon longer. Nobody disputes that the Amazon carries more water than any other river.
Examples
Follow one river: the Mississippi starts as a small stream flowing out of Lake Itasca in Minnesota, collects tributaries such as the Missouri and the Ohio, and flows south about 3,770 km (2,340 miles) to a large delta in Louisiana.
| River | Where | Something to know |
|---|---|---|
| Nile | Africa | flows north into the Mediterranean Sea |
| Amazon | South America | carries the most water of any river |
| Niger | West Africa | joined by the Benue in Nigeria; ends in the Niger Delta |
| Thames | England | flows through London to an estuary |
Common mistakes
- Thinking rivers always flow south. Rivers flow downhill in any direction. The Nile flows north.
- Mixing up source and mouth. The source is the start; the mouth is the end, like a river "speaking" into the sea.
- Saying rivers are salty. River water is fresh. It becomes salty only where it mixes with the sea.
Quick quiz
Rivers
Check what you know with 4 quick questions.
Question 1 of 4
What is the source of a river?
Practise it
Try it
- What is the place where a river begins called?
- What do we call the big loops a river makes on flat land?
- Which river carries the most water in the world?
Answers: 1) The source. 2) Meanders. 3) The Amazon.
Rivers and geography practice
For grown-ups
Related topics
The water cycle
The water cycle is the endless movement of water between the land, the sea and the sky. Water evaporates, condenses into clouds, falls as rain or snow and collects in rivers and oceans.
Oceans
Oceans are the huge bodies of salt water that cover most of Earth. There are five: the Pacific, Atlantic, Indian, Southern and Arctic.
Mountains
A mountain is a very high landform with steep sides and a peak. Most form when tectonic plates push together or when volcanoes build up.
Maps
A map is a drawing of a place seen from above. A key explains its symbols, a scale shows real distances and a compass shows direction.
The Amazon River
The Amazon is a huge river in South America that carries more water than any other river on Earth. It flows about 6,400 km from the Andes across Brazil to the Atlantic Ocean.
The River Nile
The Nile is a river in Africa, about 6,650 kilometres long. It flows north through Uganda, Sudan and Egypt to the Mediterranean Sea and is usually named the world's longest river.