Saturday, February 14, 2009

2008 flood in Bihar

2008 flood in Bihar

On 18 August 2008, the Kosi river picked up an old channel it had abandoned over 100 years ago near the border with Nepal and India. Approximately 2.7 million people were reported affected as the river broke its embankment at Kusaha in Nepal, thus submerging several districts of Nepal and India. 95% of total flow of the Koshi was reported flowing through the new course. The worst affected districts included Supaul, Araria, Saharsa,Madhepura, Purnia, Katihar, parts of Khagaria and northern parts of Bhagalpur, as well as adjoing regions of Nepal. Relief work was carried out with Indian Air Force helicopters by dropping relief materials from Purnia in the worst hit districts where nearly two million persons were trapped. It has not been possible to assess the magnitude of deaths or destruction, because the affected areas are totally inaccessible. 150 persons are reported to have been washed away in a single incident (Dainik Hindustan, Darbhanga edition). Another news item stated that 42 people had died in the flood in Bihar.
The Government of Bihar has constituted a technical committee, headed by a retired engineer-in-chief of the water resource department to supervise the restoration work and closure of the breach in the East Kosi afflux embankment. Indian authorities were working to prevent further widening of the breach and channels would be dug to direct the water back to the main river bed.
The fury of the Kosi river left at least 2.5 million people marooned in eight districts of Bihar and inundated 650 km². The prime Minister of India declared it a national calamity. The Indian army and non-government organizations were operating the biggest flood rescue operation in India in more than 50 years. It is reported as the worst flood in the area in 50 years.

Glaciers, glacier lakes and GLOF
At present, in the Himalayan region, glaciers are melting and retreating resulting in formation of lakes insecurely dammed by ice or moraines. These dams are at risk of failing, causing a Glacial Lake Outburst Flood (GLOF) with flows as great as 10,000 cubic meters a second. Such floods are likely to destroy communication systems and various infrastructures like bridges roads, hydropower projects (directly or indirectly), foot trails, villages, fields and terraces, irrigation canals, and could cost hundreds or even thousands of lives. Such floods also transport huge amounts of sediment.
In the past two decades GLOF has become a topic of intense discussion within the development community in Nepal. Studies of the glaciers and glacier lakes were carried out in 1988 by a joint Sino-Nepalese team. In the Arun-Koshi river basin, there are 737 glaciers in Tibet and 229 glacier lakes, out of which 24 glacier lakes are potentially dangerous. Similarly, there are 45 glacier lakes in the Sun-Koshi basin, out of which 10 are potentially dangerous.
The Dig Tsho GLOF on 4 August 1985, completely destroyed the nearly completed Namche hydropower plant and also all the bridges, trails, cultivation fields, houses and livestock along its path to the confluence of the Dudh-Koshi and the Sun-Koshi rivers at a distance of 90 km (56 mi) from the Dig Tsho glacier. The Dig Tsho glacier is on the terminus of the Langmoche Glacier. This event brought into focus the seriousness of such events and the studies to assess the glaciers, glacier lakes and GLOF followed.
According to a Sino-Nepalese study, since the 1940s, there have been at least 10 cases of glacier lake outbursts within the basins investigated. Among them there have been five bursts in three glacier lakes of the Arun River Basin, and four in three glacier lakes of the Sun Koshi River Basin.

1 comment:

Unknown said...

Please join to find lasting solution for Kosi.