Thursday, August 28, 2008

Kosi river flood : The complete story

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 reaches of the river in Nepal, sediment/silt in the river is carried to the plains where the slopes are flatter beyond Chatra resulting in deposition of sediment bed load and high aggradation of the river bed causing a number of interlacing channels, which shift their channels laterally from time to time. The excessive rains, large flood discharge during the monsoon and erosion prone low banks in the plains compound the problem of floods in the highly braided river in the plains of Nepal and north Bihar, inducing pendulum action starting at the bends and triggering extensive damages to life and property in the thickly populated lower plains of the river basin in Nepal and Bihar (more so in Bihar). To this is owed its epithet “River of Sorrow”.

The 2008 floods

Thousands of people were marooned in Bihar after the Kosi river breached its banks upstream in Nepal, flooding villages and towns in many areas across the state. The floods have claimed 55 lives so far.

Floodwaters entered new areas on Tuesday and have affected two million people so far in Supaul, Araria and Madhepura districts.

Chief Minister Nitish Kumar said that a breach in the Kosi embankment near Kusaha in Nepal had forced the river to change its course, for the first time since the 1950s.

The Chief Minister said it was not a normal annual flooding, but a catastrophe.

Most of the marooned people have been without food and water for five days. Despite the government maintaining that it has air dropped relief material and set up relief camps, crowds of displaced people perched on embankments were seen protesting against inadequate government help.

"This time, the flood has been caused by a two km breach in the embankment of river Kosi. The government has initiated moves to plug it," Ajay Naik, principal secretary in the water resources department, said.Stay connected to Speak India and become an active Indian by subscribing to this blog. Subscribe in a reader or enter your email address below

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