The World's Great Rivers

Rivers: The Veins of the Earth

If you could look down on our planet from space, you would see thin, winding silver threads stretched across the land. These are rivers — moving ribbons of fresh water that carve their way from the mountains to the sea.

Rivers may look gentle, but over thousands of years they have shaped our world. They have carved deep canyons, built fertile plains, and watered the fields where the first great cities grew. For most of human history, rivers were the roads, the water supply and the lifeblood of the people who lived beside them.

In this book we will follow the journey of a river from beginning to end, then travel the globe to meet some of the greatest rivers on Earth. Let's set off downstream.

How a River Forms

Every river has a story that begins high above the sea. The place where a river starts is called its source. A source might be a bubbling spring, water from melting snow or ice, or a stream flowing out of a mountain lake.

Pulled by gravity, the water flows downhill. Tiny trickles join together to form streams, and streams join to form a river. Each smaller stream that flows into the main river is called a tributary. As more tributaries join, the river grows wider and more powerful.

The whole area of land that drains its rainwater into one river is called the river's basin or catchment. The Amazon basin, for example, is larger than most countries.

Finally the river reaches its end, called its mouth, where it empties into a sea, an ocean or a lake. Along the way the river may have travelled thousands of kilometres.

From Source to Mouth

A river changes character along its journey. Near its source in the highlands, the river is usually narrow, fast and noisy, tumbling over rocks and waterfalls. The rushing water has great energy and cuts downward into the rock, sometimes carving deep valleys and gorges.

In its middle course, the land flattens out. The river slows, widens, and begins to bend. These looping bends are called meanders. Here the river carries tiny pieces of rock and soil, called sediment, along with it.

Near the mouth, the river is at its widest and slowest. It drops its load of sediment, building up flat, fertile land. Where the river fans out into many channels as it meets the sea, it forms a triangle-shaped area called a delta. The Nile Delta and the Mississippi Delta are famous examples, and their rich soil makes them excellent for farming.

The Nile: River of Ancient Egypt

The Nile in north-east Africa is usually named the longest river in the world, flowing about 6,650 kilometres from the highlands of central Africa northward to the Mediterranean Sea.

Unlike most rivers, the Nile flows from south to north. Each year, before modern dams were built, it used to flood and spread rich black mud across its banks. This made the land beside it perfect for growing crops, even though it ran through one of the driest deserts on Earth.

Because of this gift, one of the world's first great civilisations — ancient Egypt — grew up along the Nile more than 5,000 years ago. The Egyptians relied on the river so completely that they called their land "the gift of the Nile."

The Amazon: The Mightiest River

The Amazon in South America may not be the longest, but it is without question the most powerful. It carries more water than any other river on Earth — more than the next seven largest rivers combined. In places it is so wide you cannot see the far bank.

The Amazon begins high in the Andes Mountains in Peru and flows across the continent to the Atlantic Ocean. Along the way it gathers more than a thousand tributaries.

The river runs through the Amazon Rainforest, the largest tropical rainforest in the world. This is home to an astonishing variety of life, including pink river dolphins, electric eels, piranhas and the giant anaconda. Scientists believe many of its creatures have still not been discovered.

Asia's Great Rivers

Asia, the largest continent, is home to some of the most important rivers on the planet.

The Yangtze in China is the longest river in Asia and the third-longest in the world. Hundreds of millions of people live in its basin, and it has been a vital route for trade and travel for thousands of years.

The Ganges, which flows through India and Bangladesh, is considered sacred by millions of Hindus, who travel to bathe in its waters. Like the Yangtze, it supports vast farmlands that feed huge numbers of people.

Further west, the Tigris and Euphrates rivers gave their name to Mesopotamia, meaning "the land between the rivers." It was here, thousands of years ago, that some of the very first cities and the first writing appeared.

Rivers of Europe and North America

In Europe, the Danube flows through ten countries — more than any other river in the world — passing famous cities such as Vienna, Budapest and Belgrade. The Rhine has been a busy highway for boats and trade for centuries.

In North America, the Mississippi drains the heart of the United States, gathering water from the Rocky Mountains in the west to the Appalachians in the east before reaching the Gulf of Mexico. Riverboats once carried goods and people up and down its great length, and it remains a vital route today.

Why Civilisations Grew Beside Rivers

Have you noticed that so many of the world's first cities began beside rivers? This was no accident.

Rivers gave early people almost everything they needed. They provided fresh water to drink and water for crops. Their yearly floods spread fertile soil. They were full of fish to eat. And they were natural roads, allowing people to travel and trade by boat long before there were proper roads on land.

Because of all this, the great early civilisations of Egypt, Mesopotamia, India and China all grew up along rivers. We sometimes call these the "river valley civilisations." Even today, most of the world's largest cities sit on a river or close to one.

Caring for Our Rivers

Rivers are precious, but they can be harmed. When factories, farms and cities pour waste into rivers, the water becomes polluted and the fish and other wildlife suffer. Taking too much water for crops and cities can leave rivers running low.

Rivers also connect everything along them, so pollution upstream affects people and animals far downstream. This is why countries that share a river must work together to keep it healthy.

Around the world, people are now cleaning up rivers, removing old dams to let fish swim freely, and protecting the wetlands that act as natural filters. A healthy river is one of the most valuable things a country can have.

What We Learned

We have followed rivers from their mountain sources all the way to the sea, and travelled the globe to meet the greatest among them.

A river forms from rain, snow and springs, gathering tributaries as it flows from source to mouth, carving valleys and building fertile deltas. The Nile is the longest, the Amazon the most powerful, and rivers like the Yangtze, Ganges, Tigris and Mississippi have shaped human history. The first great civilisations grew up beside rivers because rivers gave water, food, soil and a way to travel.

Rivers are truly the veins of the Earth — and protecting them protects us all.

Want to keep exploring the planet? Stand on the rooftops of the world in Mountains of the World, or marvel at the planet's most astonishing places in Natural Wonders of the World.