Bihar devastated by Kosi

The Kosi river, which gathers water from Everest, the highest mountains in the world  and enters India in  Bihar, has  rendered useless more than 300km of embankments that had been built to control its ever-angry waters. The effect has been enormous, inundating numerous towns and villages that had not seen such floods for decades. 
The Kosi is called the Sorrow of Bihar because among all the fast-flowing rivers that collect water in Nepal and speed down the mountains into the plains of Bihar, it is the most dangerous. It carries over 81 million tons of silt every year in its roiling waters.
And, it is a young river, not yet having matured enough to settle on a course. As it enters the northern plains the incline drops off, and the water starts slowing down. Over the years silt gets deposited giving Kosi its braided shape — it has several channels that diverge and then again merge, like a braid, as the water tries to find new ways to go further. As it shifts it leads a deposit of sand, which renders the land barren.

Seen from a satellite, the area looks like a conical fan. Created by hundreds of years of shifting, it is the largest such cone in the world, covering an area of over 15,000 square km. The tip is near Chatra on the Nepal border. The cone is made up of various courses of Kosi and the land in between, which gets submerged during floods.

The Kosi used to wind its way on the eastern-most course. But as the silting raised the level of the bed, it kept shifting westwards. However, because there is an incline from the west to the east, the waters couldn’t move westward any more and returned to the eastern course once again.

Experts argue that building embankments allowed too much silt deposition in a shorter stretch, leading to devastation. In other words, young Kosi is not being allowed to grow up and settle down. Meanwhile, people have to adjust to a new reality, the Kosi flowing in its new course, redefining fields, roads and boundaries.

Source:Times Of India