Kosi River

Bhote Koshi in Nepal

The Koshi (also Kosi; Nepali: कोशी, Kosi ) is a transboundary river between Nepal and the Indian state of Bihar, and one of the largest tributaries of the Ganges. The river, along with its tributaries, drains a total area of ​​69,300 km ² up to its confluence with the Ganges in India at Kursela east of Bhagalpur. The area of the watershed is located in Tibet, still north of the Mount Everest region, belonging as the eastern third of Nepal to the catchment area. This is surrounded by mountain ridges, which separate it from the catchment areas of the Brahmaputra in the north, the Gandaki in the west, the Mahananda in the east and the Ganges in the south.

The river, which is called on the Nepalese side Sapt Koshi, about 48 km north forms the Indo- Nepal border in the rivers of Sun Koshi, Arun and Tamor. The course of the river has been twelve times sought a new riverbed in the last 250 years of floods and thereby about 120 km westward shift. Kamla, Bagmati ( Kareh ) and Budhi Gandak are the main tributaries of the Koshi in India, in addition to smaller tributaries such as the Bhutahi Balan.

The instability of the flow curve is due to the high silt content, the transports water during the monsoon season. The floods in India have extreme effects. India to Bangladesh has the second largest number of deaths in the world due to floods. The Koshi, Gandaki after the main river to the drainage basin of northern Bihar, is one of the most flood-prone areas of India.