Posted on by Elizabeth Howell

What Is The World’s Widest River?

The Amazon River near Lago do Erepecu (north of this image) in 2014. Credit: NASA

The Amazon River is a heck of a big tributary. Besides being one of the LONGEST rivers in the world, it also happens to be the WIDEST. While its estimated length of 4,000 miles (6,400 kilometers) puts it under the Nile River, that statistic could be amended as some believe it’s even longer than that.

Nevertheless, its width puts it at a big river that carries more volume than the Nile. We have a few more facts about the Amazon below.

According to Extreme Science, even during the dry season it is about 6.8 miles (11 kilometers) wide, which is still a respectable width. When things get rainy, however, that’s when stuff really begins to open up. It more than doubles its width to 24.8 miles (40 kilometers).

If that’s enough for you, consider the amount of land it covers. Dry season, Extreme Science says, sees it at 42,471 square miles (110,000 square kilometers), or roughly the land area of Cuba. That astonishing statistic triples during the wet season, when it reaches 135,135 square miles (350,000 square kilometers) — about approximate to Germany’s size.

Mouth of the Amazon River as seen from STS-58
Mouth of the Amazon River as seen from STS-58. Credit: NASA

All of this makes the South American river the largest drainage system in the world, according to Encyclopedia Britannica. Its recorded source is in the Andes Mountains and it flows down to its Atlantic Ocean mouth off the coast of Brazil. But as we’ve noted before, there’s controversy both to its source and to its actual length.

The Amazon basin (the areas that are affected by the river) cover a good portion of South America, the encyclopedia adds: Brazil, Peru, Columbia, Ecuador, Bolivia and Venezuela. But it’s Brazil that has most of the basin and two-thirds of the stream.

Aboriginals in the region have explored the river for centuries, but its name comes from European exploration of the river, the encyclopedia says. “Amazon” is a reference from Europe’s first reported explorer, Spanish soldier Francisco de Orellana, who said the fierce female warriors in battle in the area reminded him of Amazons in Greek mythology.

Mouth of Amazon River, Brazil as seen from the Gemini 9-A spacecraft
Mouth of Amazon River, Brazil as seen from the Gemini 9-A spacecraft. Credit: NASA

Many of these statistics could change if the source of the Amazon River is also changed. National Geographic says there at least six possible origin points, based on methods ranging from satellite observation to GPS to “ground truth” examinations. You can see more details about the ongoing quest in this article.

Universe Today has articles on the longest river  and Europe’s longest river. Astronomy Cast has an episode on Earth you should watch.

Posted on by Jerry Coffey

Largest River In The World

Nile River
Nile River

[/caption]The largest river in the world can be hard to calculate. Many factors come into play: the source, the identification of the mouth, and the measurement of the river length between source and mouth. As a result, the measurements of many rivers are only approximations. So, there has been disagreement whether the Amazon or the Nile is the world’s largest river based on the inclusion of estuaries.

The mouth of a river is hard to determine in cases where the river has a large estuary that gradually widens and opens into the ocean. The source of some rivers starting in farming areas can be difficult to determine, if the river is formed by the confluence of several farm field drainage ditches which only contain water after rain. Similarly, in rivers starting in a chalk area the length of the upper course which is dry varies with how high the water table is. How large a river is between source and mouth may be hard to determine due to issues of map scale. Small scale maps tend to generalize more than large scale maps. In general, length measurements should be based on maps that are large enough scale to show the width of the river, and the path measured is the path a small boat would take down the middle of the river.

Given, and despite, this ambiguity, the Nile has been determined to be the largest river in the world followed by the Amazon and the Yangtze. The Nile is a north-flowing river in North Africa. It is 6,650 km long. It has two major tributaries, the White Nile and the Blue Nile. The Blue Nile is the source of most of the water and fertile soil in the system. The White Nile is longer and rises in central Africa beginning in Rwanda. The two rivers meet near the Sudanese capital of Khartoum. The northern section of the Nile flows almost entirely through desert. Most of the ancient civilizations of the area were centered along the river’s banks. The Nile ends in a large delta that empties into the Mediterranean Sea.

The debate over which is the largest river in the world seems to be over for now. The Nile is 250 km larger than the Amazon. Both rivers have played important roles in the evolution of the civilizations that sprang up around them and will continue to do so for centuries to come.

We have written many articles about rivers for Universe Today. Here’s an article about the world’s widest river, and here’s an article about the longest river in the world.

If you’d like more info on rivers, check out Visible Earth Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
http://news.nationalgeographic.com/news/2007/06/070619-amazon-river.html
http://news.bbc.co.uk/2/hi/6759291.stm