KOSI RIVER (Syllabus: GS Paper 1 - Geography)

Context: A flood-like situation in low-lying areas of north Bihar districts has forced hundreds of families to flee in search of safer locations. 

• With major rivers and their tributaries in spate, thousands are in fear of floodwater entering their houses.
• While the Koshi, Gandak, Bagmati, Mahananda, Ganga and Adhwara are flowing above the danger mark at several places, they are close to the safe limits in some other regions.
• In the Himalayan reaches, the course of these rivers is highly tortuous, but over the plains they display a strong meandering tendency and shift their courses frequently.

Kosi River

• River Kosi, also known as the ‘sorrow of Bihar’, has been notorious for frequently changing its course.

• The Kosi brings huge quantity of sediments from its upper reaches and deposits it in the plains.
• The course gets blocked, and consequently, the river changes its course.
• The Kosi is a trans-boundary river which flows through Tibet, Nepal and India.
• It has its source in Tibet that includes the world's highest upland, it then drains a large part of Nepal before emerging onto the Gangetic plains.
• Its three major tributaries, the Sun Kosi, Arun and Tamur meet at one point just upstream of a 10 km gorge cut through the Himalayan foothills.
• The river crosses into northern Bihar, India where it branches into distributaries before joining the Ganges near Kursela in Katihar district.
• The Kosi carries the maximum amount of silt and sand after the Brahmaputra in India.