Meeting of waters of Amazon and Rio Negro rivers in Brazil. 2005

The black waters of the Rio Negro River meet the sandy-beige Amazon River, or rather one of its tributaries, the Solimines about 10 kilometers from Manaus city in northern Brazil. The waters don’t mix right away. They flow shoulder to shoulder for 6 km. This natural phenomenon is known as the “the waters’ meeting” or “Encontro das Águas” in Portuguese. This phenomenon occurs in several places in the Amazon basin, as well as in other places on the planet, but nowhere so abruptly as here.

This is due to the difference in ‘both rivers’ components in speed, temperature, and density. The Solimines River speed averages 5 km / h and the water temperature is 22 ° C. Rio Negro flows at a speed of 2 km / h, and its temperature is 28 ° C.

The Rio Negro River is the largest left tributary of the Amazon River. Since the river flows through numerous forests and swamps, its waters wash away various plant components, which immediately decompose. Therefore, the river water is black due to the organic compound’s high concentration. On the other hand, there is a thick layer of sand and mud in Solimines River waters, which also determines its color. But in the end, the two rivers merge into one and form the Amazon River’s lower course.