What is a River?
Learn about River’s and their history over time…
A river is a large, natural stream of flowing water. Rivers are found on every continent and on nearly every kind of land. Some flow all year round. Others flow seasonally or during wet years. A river may be only kilometres long, or it may span much of a continent.
The longest rivers in the world are the Nile in Africa and the Amazon in South America. Both rivers flow through many countries. For centuries, scientists have debated which river is longer. Measuring a river is difficult because it is hard to pinpoint its exact beginning and end. Also, the length of rivers can change as they meander, are dammed, or their deltas grow and recede.
The Amazon is estimated to be between 6,259 kilometres (3,903 miles) and 6,800 kilometres (4,225 miles) long. The Nile is estimated to be between 5,499 kilometres (3,437 miles) and 6,690 kilometres (4,180 miles) long. There is no debate, however, that the Amazon carries more water than any other river on Earth. Approximately one-fifth of all the freshwater entering the oceans comes from the Amazon.
Rivers are important for many reasons. One of the most important things they do is carry large quantities of water from the land to the ocean. There, seawater constantly evaporates. The resulting water vapour forms clouds. Clouds carry moisture over land and release it as precipitation. This freshwater feeds rivers and smaller streams. The movement of water between land, ocean, and air is called the water cycle. The water cycle constantly replenishes Earth’s supply of fresh water, which is essential for almost all living things.
Rivers Through History
Rivers have always been important to people. In prehistoric times, people settled along the banks of rivers, where they found fish to eat and water for drinking, cooking, and bathing.
Later, people learned that the fertile soil along rivers is good for growing crops. The world’s first great civilizations arose in the fertile flood plains of the Nile in Egypt, the Indus in southern Asia, the Tigris and the Euphrates in the Middle East, and the Huang (Yellow) in China.
Centuries later, rivers provided routes for trade, exploration, and settlement. The Volga River in Eastern Europe allowed Scandinavian and Russian cultures, near the source of the river, to trade goods and ideas with Persian cultures, near the mouth of the Volga in southern Europe. The Hudson River in the U.S. state of New York is named after English explorer Henry Hudson, who used the river to explore what was then the New World.
When towns and industries developed, the rushing water of rivers supplied power to operate machinery. Hundreds of factories operated mills powered by the Thames in England, the Mississippi in the United States, and the Ruhr in Germany.
Rivers remain important today. If you look at a world map, you will see that many well-known cities are on rivers. Great river cities include New York City, New York; Buenos Aires, Argentina; London, England; Cairo, Egypt; Kolkata, India; and Shanghai, China. In fact, rivers are usually the oldest parts of cities. Paris, France, for instance, was named after the Iron Age people known as the Parisii, who lived on the islands and banks of the Seine River, which flows through the city.
Rivers continue to provide transportation routes, water for drinking and for irrigating farmland, and power for homes and industries.