Satellite image of Kosi River during flood of 2008 (NASA)

I was recently in Patna, the capital of the state of Bihar in northern India, talking about the ‘Kosi problem’. Bihar shares a border with Nepal and the rivers which flow out of the Himalayas and into Bihar are prone to disastrous floods caused by the enormous volumes of sediment and water that they carry. In August 2008, during one of the most recent floods, the Kosi River burst through one of its levees and flowed back into one of its abandoned channels, following a much straighter and steeper path toward the Ganga River and eventually to the Bay of Bengal. This large-scale shift of the river, called an avulsion, is a frequent occurrence on the Kosi – or at least it was until 1953, when the Indian government began an ambitious programme of dam and levee construction designed to tame the Kosi and ‘train’ it into a straight and well-defined course.

The problem is that this programme took no notice of either (1) the sediment load carried by the Kosi, which is now piling up between the levees and making an avulsion more and more likely, and (2) the needs and desires of the local populations, who were effectively abandoned to their fates once the levee system was completed. In the 2008 flood which resulted from this neglect, 3.3 million people – residents of the poorest state in India – were displaced from their homes, and many areas of the fan remained under water for more than 9 months before the river finally drained away.

Together with Prof Rajiv Sinha of the Indian Institute of Technology Kanpur, I’ve been working for the last few years on understanding what makes the Kosi such an active river, and on how and where this enormous sediment load is derived and deposited. We convened the workshop on the Kosi to bring together natural and social scientists, engineers, river managers, NGO and government officials in order to understand our current state of knowledge. What basic work can we do that would have the greatest impact on building flood-resilient communities, and that would prevent a repeat of the 2008 disaster? It was pleasing to see a powerful array of people in the room – the state Secretary of Roads, the vice chairman of the State Disaster Management Authority, the head of river management at the Central Water Commission, and the chairman of the Ganga Flood Control Commission. The talks and the passionate, often emotional debate that followed highlighted two basic points that are fundamental to the way we think about risk and resilience.

First, our technical understanding of the river’s physical behaviour has made enormous strides in the last decade, where our many different points of view converged on an innovative strategy of breaching the levees and allowing controlled flooding and sediment transport through the network of abandoned river channels during high flows. But second, and more importantly, was the recognition that no one at any stage in this shameful saga actually bothered to ask the residents of the Kosi region what they wanted from a flood control scheme, or indeed whether they wanted one at all. The Bihari culture has long been adapted to yearly floods, and this was incorporated into crop rotation, patterns of migration and ways of sharing resources between villages during bad years. And yet even now, the residents have no voice in the decisions that are being taken about their livelihoods. This workshop was a small step – but a step nonetheless – toward a more sustainable way of managing the Kosi River and avoiding a repeat of this eminently avoidable disaster.

Further Reading

Water experts to discuss cause of floods. The Times of India