Thinking Citizen Blog — The Amazon

Thinking Citizen Blog — Wednesday is Climate Change, the Environment, and Sustainability Day

Today’s Topic — Great Rivers of the World (III) — The Amazon — the drainage basin, Manaus, wildlife.

Measured by discharge volume, the Amazon is bigger than the next seven largest rivers combined! The standard metric is meters cubed per second — 209,000 in the case of the Amazon. Number two is the Congo at 41,000. The largest tributary of the Amazon is the Rio Negro, the world’s largest blackwater river, which merges with the Upper Amazon (called the Rio Solimoes in Brazil), at Manaus, the seventh-largest city in Brazil. At the river’s mouth is the city of Belem. No bridge crosses the Amazon. Experts — please chime in. Correct, elaborate, elucidate.


1. The Amazon accounts for 20% of the world’s total river volume.

2. The Amazon Rainforest accounts for 50% of the world’s rainforests.

3. The drainage basin covers 40% of South America


1. To me, one of the most stunning pictures in all of geography. The dark stream is the Rio Negro. The sandy colored one is the Upper Amazon (called the Rio Solimoes by Brazilians).

2. The rivers run side by side without mixing for 3.7 miles.

3. “This phenomenon is due to the differences in temperature, speed and water density of the two rivers. The Rio Negro flows at near 2 km/h (1.2 mph) at a temperature of 28 °C (82 °F), while the Rio Solimões flows between 4 and 6 km/h (2.5–3.7 mph) at a temperature of 22 °C (72 °F).”

NB: Manaus was once the wealthiest city in South America (thanks to the rubber boom of the late 19th century). The boom left behind a stunning architectural legacy including a renowned opera house, the Teatro Amazonas.

EXTRAORDINARY WILDLIFE — including the Arapaima, a huge freshwater fish

1. “More than a third of the world’s known species live in the Amazon rain forest” and more new species are being discovered every year.

2. The Arapaima (above) is one of the largest freshwater fish in the world, and the “boto” is one of the biggest river dolphins. The Kuma Kuma is a catfish that can reach12 feet in length.

3. And then, of course, there is the notorious piranha, most of which are apparently not a threat to humans.

NB: Deforestation is a huge threat to biodiversity in the Amazon rain forest. Cattle ranching accounts for about 80% of the decline. About a third of the rain forest belongs to 3344 “indigenous territories.”

Amazon River

Meeting of Waters


Amazon rainforest

Indigenous territory (Brazil)

List of rivers by discharge

List of cities in Brazil by population

Blackwater river



Please share the coolest thing you learned in the last week related to climate change or the environment. Or the coolest, most important thing you learned in your life related to climate change that the rest of us may have missed. Your favorite chart or table perhaps…

This is your chance to make some one’s day. Or to cement in your own mind something that you might otherwise forget. Or to think more deeply than otherwise about something dear to your heart.



Passionate about education, thinking citizenship, art, and passing bits on of wisdom of a long lifetime.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
John Muresianu

Passionate about education, thinking citizenship, art, and passing bits on of wisdom of a long lifetime.