Whitewater river (river type)

This classification system was first proposed by Alfred Russel Wallace in 1853 based on water colour, but the types were more clearly defined according to chemistry and physics by Harald Sioli [de] from the 1950s to the 1980s.

[7][8][9] Although many Amazonian rivers fall clearly into one of these categories, others show a mix of characteristics and may vary depending on season and flood levels.

The main whitewater rivers are Solimões–Amazon, Caquetá–Japurá, Putumayo, Marañón, Ucayali, Javary, Juruá, Acre, Purus, Madre de Dios, and Madeira.

[8] Although the Branco River traditionally is considered whitewater,[11][12] it has a number of characteristics (some of them varying with season) that do not fit clearly into the classification and some refer to it as clearwater.

[18] In Asia, examples are the Mekong mainstream (especially in the rainy season),[19] and several upland streams in large river basins in the southern and southeastern part of the continent.

[20] In South America, most whitewater rivers originate in the Andes where they collect high levels of nutrient-rich sediments, notably illite and montmorillonite.

[22] Consequently, although the Amazon River is whitewater throughout its course, the electric conductivity is 120–200 μS/cm in the Andes, but by the time it reaches Santarém (after the inflow of Rio Negro, Tapajós, and some smaller black- and clearwater tributaries), it has fallen to 40-70 μS/cm.

[28] The major seasonal Amazonian floodplains known as várzea receive their water from whitewater rivers and are home to many animals and plants.

[30] Due to the high level of prey fish, the largest group-size of Inia river dolphins are in sections of the Amazon and Orinoco basins that are directly influenced by whitewater.