History of the sorrow of Bihar Koshi or Milk River is known as the “Sorrow of Bihar” when it flows from Nepal to India, as it has caused widespread human suffering in the past due to flooding and very frequent change in course. Koshi has an average water flow (discharge) of 1564 cumecs (cubic metres per second) or 55,000 cubic feet per second (cusecs). During peak floods, it increases to about 18 times over. The highest flood recorded in living memory in the river is reported to be 24,200 cumecs (8,50,000 cusecs) on August 24, 1954 and the Koshi Barrage has been designed for a peak flood of 27,014 cumecs (950,000 cusecs). Due to extensive soil erosion and land slides in its upper catchment by factors both natural and human, the silt yield of Koshi is about 19 cum/ha/year, one of the highest in the world. The Arun, with its origins in Tibet, brings the greatest amount of coarse silt in proportion to its total sediment load. On account of the steep slopes and narrow gorges in the upper r...