Mero Dolakha: Koshi River

After long time back, today I could manage a free time to post something in this blog and I thought to share some experience of my Koshi River visit on January 16. 2012. My office, ICHARM, organized a Knowledge Sharing Workshop on Water-related Disaster Risk Management on January 15-18, 2012 in Kathmandu Nepal. During the workshop, we also had a field site survey at Koshi River Barrage for the site survey of flood affected areas of Koshi flood 2008. There was severe damaged by 2008 flood.

The Kosi River for its seven Himalayan tributaries—is a trans-boundary river flowing through Nepal and India. Some of the rivers of the Koshi system, such as the Arun, the Sun Koshi and the Bhote Koshi, originate in the Tibet Autonomous Region of China. It is one of the largest tributaries of the Ganges. Along with its tributaries, the river drains 29,400 km2 (11,400 sq mi) in China (mainly the upper Arun basin north of the Mount Everest region), 30,700 km2 (11,900 sq mi) in Nepal (the eastern third of the country), and 9,200 km2 (3,600 sq mi) in India. Over the last 250 years, the Koshi River has shifted its course over 120 km (75 mi) from east to west. Its unstable nature has been attributed to the heavy silt it carries during the monsoon season. Flooding in India has extreme effects, and the country is second in the world after Bangladesh in deaths due to flooding, accounting for one fifth of global flooding deaths. The Koshi River (The Sorrow of Bihar) is one of two major tributaries, the other river being the Gandaki, draining the plains of north Bihar, the most flood-prone area of India.

Koshi flood disaster of 18th August 2008

The breach on the embankment of the Koshi River (12.6km upstream of barrage) occurred on 18th August 2008 at 12:45PM. At the time of breaching, about 168 thousand cusec of water diverted into Kusaha, Laukahi, Ghuski, Sreepur, Haripur, Narshimha, Madhuban and Basantapur VDC of Sunsari district. It caused the displacement of more than 107,200 people in Nepal. Progression of embankment breaching took place at the rate of about 500m in every five hours. It is the countr’s worst flooding in five decades. Rains during caused the embankment to collapse. When the Koshi River changed its course towards the east, beaching 1.7km of its left embankment and it deposited silt on the flood affected area and adjoining villages covering 5475 hectors of agricultural land. About 80% of flow passed through the breached section. The death toll would have been very high if the flood had occurred at night. At the time of disaster about 15kilometers of the East West highway was obstructed and 3 kilometers was destroyed. About two thirds of houses were severely damaged as most of them were huts made of mud, bamboo and thatch. These houses were generally one story high. The floor and walls were mud plastered. It caused extensive damage to the optical fiber cable network laid along the highway.

Data Source links: (online accessed December 30, 2011)

http://en.wikipedia.org/wiki/Koshi_River