Key Facts about Kosi River

About Kosi River:

• It is atransboundary river which flows through China, Nepal and India.
• It is a prominent tributary of the Ganges.
• Course:
  • Origin: The river Kosi is formed by the confluence of three streams, namely the Sun Kosi, the Arun Kosi, and the Tamur Kosi, all of which have their origin in the Himalayan region of Nepal and Tibet. 
  • About 30 miles (48 km) north of the Indian-Nepalese frontier, the Kosi is joined by several major tributaries and breaks southward through the Siwalik Hillsat the narrow Chatra Gorge. 
  • The river then emerges on the great plain of northern India in Bihar state on its way to the Ganges River, which it enters south of Purnea after a course of about 450 miles (724 km). 
• The Kosi drains an area of 74,500 sq.km, of which only 11,070 sq.km lie within Indian Territory. 
• The Kosi River valley is bounded by steep margins that disconnect it from the Yarlung Zangbo River to the north, the Mahananda River to the east, the Gandaki to the west, and the Ganga to the south.
• Because of its great outflushing of debris, the Kosi has no permanent channel in its course through the great plain of northern India.
• It is well known for its tendency to change course generally in a westward direction. During the last 200 years, the river has shifted westwards for a distance of about 112 km and has laid waste large tracks of agricultural land.
• Kosi is known as the "sorrow of Bihar", as it has caused widespread human suffering in the past due to flooding and very frequent course changes when it flows from Nepal to Bihar.
• Tributaries: It has seven major tributaries: Sun Koshi, Tama Koshi or Tamba Koshi, Dudh Koshi, Indravati, Likhu, Arun, and Tamore or Tamar.