Rio and tributries

The Amazon river flows from headwaters in the towering Andes, crosses vast rainforests, meanders through the lowlands of Brazil, empties into a massive delta, and then joins the Atlantic Ocean. It traverses lands so vast and remote that measuring its length has proved a formidable task. Along the river’s route some thirteen major tributaries carry the waters of Amazonia into its path, creating South America’s greatest river and by many accounts the longest river in the world:

The Amazon has over 1,100 tributaries, 17 of which are over 1,500 kilometres (930 mi) long.
Here is a list of the more notable ones.
Click on the name to read more about them on Wikipedia.

6,259.2 km (3,889.3 mi) to 6,712 km (4,171 mi) – Amazon, South America
3,250 km (2,020 mi) – Madeira, Bolivia/Brazil
3,211 km (1,995 mi) – Purús, Peru/Brazil
2,820 km (1,750 mi) – Japura, Colombia/Brazil
2,639 km (1,640 mi) – Tocantins, Brazil
2,627 km (1,632 mi) – Araguaia, Brazil (tributary of Tocantins)
2,400 km (1,500 mi) – Juruá, Peru/Brazil
2,250 km (1,400 mi) – Rio Negro, Brazil/Venezuela/Colombia
1,992 km (1,238 mi) – Tapajós, Brazil
1,979 km (1,230 mi) – Xingu, Brazil
1,900 km (1,200 mi) – Ucayali River, Peru
1,749 km (1,087 mi) – Guaporé, Brazil/Bolivia (tributary of Madeira)
1,575 km (979 mi)    – Içá (Putumayo), South America
1,415 km (879 mi)    – Marañón, Peru
1,370 km (850 mi)    – Teles Pires, Brazil (tributary of Tapajós)
1,300 km (810 mi)    – Iriri, Brazil (tributary of Xingu)
1,240 km (770 mi)    – Juruena, Brazil (tributary of Tapajós)
1,130 km (700 mi)    – Madre de Dios, Peru/Bolivia (tributary of Madeira)
1,100 km (680 mi)    – Huallaga, Peru (tributary of Marañón)

1,050 km (652 mi)     –  Rio Jutai     Brazil (Amazonas)

760 km   (472 mil)    –Trombetas Para Brazil

1,184 km (736 mi)    – Javary      Brazil/Peru Amazonas

500 km (311 mi)       – Jandiatuba  Brazil Amazonas

Q & A’s   Rivers

Why do rivers meander/curve?

Watch the Nasa video below

Rivers flowing over gently sloping ground begin to curve back and forth across the landscape. These are called meandering rivers.
Meandering rivers sediment from the outer curve of each meander bend and deposit it on an inner curve further down stream. This causes individual meanders to grow larger and larger.
Meandering river channels are asymmetrical. The deepest part of the channel is on the outside of each bend. The water flows faster in these deeper sections and erodes material from the river bank. The water flows more slowly in the shallow areas near the inside of each bend. The slower water can’t carry as much sediment and deposits its load on a series of point bars.


Meandering river in the Amazon

Image credit Nasa

What is a tributary?
A tributary or affluent is a stream or river that flows into a main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river serve to drain the surrounding drainage basin of its surface water and groundwater leading the water out into an ocean.

What are Oxbow lakes?

Oxbow lakes form when a meander grows so big and loopy that two bends of the river join together. Once the meander bends join, the flow of water reduces and sediment begins to build up. Over time oxbow lakes will fill with sediment and can even disappear. The point where the two bends intersect is called a mean.

What is a floodplain?
The low-lying area on either side of a river is called a floodplain. The floodplain is covered with water when the river overflows it banks during spring floods or periods of heavy rain. Sediment is deposited on the floodplain each time the river floods. Mud deposited on the floodplain can make the soil really good for agriculture.


The Amazon in flood

Image credit Nasa 


What is the Várzea?

Along the Amazon River and many of its tributaries, high annual rainfall that occurs mostly within a rainy season results in extensive seasonal flooding of areas from stream and river discharge.The result is a 10–15 meter rise in water level, with nutrient rich waters. This is called the Várzea.


Vazara Flooded forest. Brazil
Vazara Flooded forest. Brazil


What is an estuary?
An estuary is a partly enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.

Estuaries form a transition zone between river environments and maritime environments. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The inflows of both sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.

Source Wikipedia.