At 6400 kilometers, or 4000 miles, in length, the Amazon River is the second longest river in the world. Twenty percent of earth’s fresh water flows through it and into the ocean at an astonishing rate of 219,000 meters cubed per second.  The width of the river extends anywhere between 4 and 50 kilometers, reaching its maximum width during the wet season[1], when increased rainfall swells the river and floods the banks.

Such a large river provides important habitats for the species of the Amazon, including over 2500 species of fish and two species of river dolphins, and provideessential ecosystem services such as the transport of nutrients like carbon and nitrogen. It also provides services for humans, such as water for agriculture, power generated by hydroelectric plants, transportation, and food.

A majority of the water that flows through the Amazon River comes from glacial melt in the Peruvian Andes, at an elevation of 5.598 m[1]It has humble beginnings in a small tributary there, but is fed along its route by over 1000 tributaries, eventually reaching a drainage basin of 7,049,948 square kilometers.

However, the balance of the water cycle in the Amazon rainforest is threatened by deforestation. Due to the process of evapotranspiration, in which trees let out water from their leaves and water evaporates from other surfaces, water vapor content is higher over forested areas. This creates clouds which affect precipitation locally and globally[2]. However, deforestation disrupts this process, and it has been shown that it leads to a loss in precipitation. This loss is especially apparent during the dry season, possibly extending it by as much as a month[2]. What’s more, deforestation doesn’t only affect precipitation – it leads to changes in river flow and discharge as well.  Since roots help to maintain water in the soil, loss of forest results in increased surface runoff. This means that there is more sediment in rivers, reducing overall volume. It also means that floods are more frequent[2]. Depending on the interactions between evapotranspiration and precipitation, river annual mean discharge may either increase or decrease as a result of deforestation, but no matter what the change is, it will disrupt the current water cycle. 

Important river basins are currently under threat of increased deforestation, as plans for construction projects such as the Interoceanica Sur Highway and hydroelectric dams are brought to completionAmazon Aid is working to reforest and protect the Amazon rainforest in order to ensure that it can continue to exist as the important component of the global water cycle it is today. To learn more about our efforts, click here.

20% of all fresh water on earth flows through the Amazon

There are more species of fish in the Amazon than anywhere else on Earth

Learn more about Water and the Amazon

Freshwater Species of the Amazon

In addition to harboring high levels of terrestrial biodiversity, the Amazon basin also contains the largest share of freshwater species in the world due to the immense size of the basin and the variety of aquatic habitat available [1]. Freshwater species in the...

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The 3 Types of Rivers in the Rainforest

In the rainforest, the color of the water in a river holds the story of the river’s origin. A river that passes through hard, rocky areas looks very different than one that passes through soft soil. The kinds of plants that grow along its course, the minerals that are...

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The Global Importance of Amazon Natural Resources

The Amazon has long been recognized as an important repository of biodiversity and natural resources. Not only for local peoples and indigenous communities, but also for the rest of the world. Unfortunately, as forests continue to disappear and the effects climate...

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A Self-Watering Rainforest

Water is a compound essential for life. It makes up about 60% of the human body and covers about 71% of the Earth’s surface. Yet researchers from the University of Exeter and Colorado State University, using computer modeling, showed evidence that the Amazon...

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