Answer: Kosi
Notes: Kosi river is known as the "Sorrow of Bihar". The Kosi is a trans-boundary river which flows through Tibet, Nepal and India. It drains the northern slopes of the Himalayas in Tibet and the southern slopes in Nepal. It is known as the Sorrow of Bihar as the annual floods affect about 21,000 km2 (8,100 sq mi) of fertile agricultural lands thereby disturbing the rural economy. It has an average water flow (discharge) of 2,166 cubic metres per second (76,500 cu ft/s).
