Following only 90mm of rainfall in 24 hours, parts of Kathmandu were underwater this week with constricted rivers overflowing and submerging roads and settlements built on their floodplains. Elsewhere in eastern Nepal which gets more than 3,000mm of rain a year is Nepal’s largest river Kosi which also has the heaviest sedimentation load for any river in the world. This was a story in Nepali Times in 2003 that accurately predicted the devastating 2008 embankment breach that submerged parts of the Tarai and Bihar.
Excerpts of a page 1 report on the 2003 Kosi flood published 20 years ago this week on issue #157 8-14 August 2003:
In 1964, India built the Kosi Barrage near the border to control the floods and to provide irrigation to farms in both countries. But standing atop one of the towers looking out at this sea-like expanse of water, it is clear that Kosi is a river that is about to go places.
The gray-brown river surges out of the mountains of eastern Nepal to join the Ganga in India, depositing some 120 million cubic metres of silt along the basin every year-twice as much as the Nile and five times more than the Sutlej. The river is now flowing several metres above the surrounding land, and only slender embankments in Nepal and Bihar keep the mighty river in check.
This week, the water flow is 200,000 cubic metres per second (cusec). Alarm bells rang last month when the flow reached 400,000 cusecs and the flood waters nearly topped the barrage. Sedimentation has raised the river bed by three metres, and even during a normal monsoon the barrage is in danger.
Experts now fear a mammoth flood, like the 800,000 cusec discharge in 1968, that could sweep away the barrage itself, unleashing devastating floods in Nepal and India. Because the river bed has been raised by sediment, even a 500,000 cusec flood, similar to the one that came down in 1987, could threaten the barrage. Since then the sediment has choked the river even more.
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