Encontro das Aguas
| Encontros das Águas | ||
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| Coordinates | 3 ° 7 '54 .4 " S , 59 ° 54' 27.5" W | |
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| place | In Manaus , Amazonas ( Brazil ) | |
The Encontro das Aguas ( meeting of the waters ) denotes the confluence of the Rio Solimões , as the Amazon is called up to this point, and the Rio Negro . It is located about ten kilometers from Manaus in the state of Amazonas / Brazil . The special thing about it is that both have a very different color (Rio Solimões brownish-yellowish, Rio Negro black) and the two streams only gradually mix.
The colors
The Amazon , a white water river , has a dirty, clay-colored appearance due to the high content of suspended mineral matter . The actually light brown color only appears white when viewed from an angle.
The Rio Negro , a black water river , gets its color from the high content of humic acids and fulvic acids that have been washed out of the already heavily depleted, sandy soils by the rain in its 720,114 square kilometer catchment area.
The confluence
First of all, it should be mentioned that the largest river on earth (Amazon) meets the second largest tributary on earth (Rio Negro) here. But these enormous masses of water do not flow into one another immediately, but eleven kilometers in the same river bed side by side before their water mixes and the river has a uniform color again. The colored border of the two rivers can be clearly seen both on satellite images and from a ship.
The reasons
The reasons for this natural event lie in the different properties of the rivers. On the one hand, the Rio Negro has a relatively acidic pH value of 3.5 , which comes from the humic substances present in the water, while the Rio Solimoes (Amazonas) has a basic pH value of 7.5. The flow speed of the two rivers differs by a factor of three. The Rio Solimoes flows with 7.5 kilometers per hour, the Rio Negro with 2.5 significantly slower. Due to the color of the two rivers, their temperatures also differ. The clayey white Solimões reflects sunlight and is always colder than 22 degrees Celsius, while the black Rio Negro absorbs it and reaches temperatures above 28 degrees. Due to the different temperature of the rivers, their density also differs significantly.
