16. Kusaha Breach Closure of Kosi River: A Case Study

The eastern afflux bundh upstream of Kosi Barrage situated at Bhimnagar in Nepal near Birpur in India got breached at Kusaha (Nepal) on 18 August 2008. The Kosi floodwater gushed out to the countryside and caused large-scale devastation lower down in one district of Nepal and five districts of Bihar. A population of about 3.3 million in India (Bihar) and 100,000 in Nepal got flood inundated. They suffered extreme damages to their lives, properties and standing crops. About 500 persons lost their lives. Important infrastructures such as railways, eastern Kosi canal systems, roads, electric transmission lines, public and private tube wells, lift and surface minor irrigation schemes, public and private buildings, etc. got severely damaged. On a rough estimate, the colossal damage to properties was of the order of about Rs. 15,000 crores. Thus, it was one of the biggest tragedies due to flood fury in the recent history.

After the breach, discharge of the Kosi approaching the Barrage about 13 km downstream became almost negligible, and the entire river avulsed into a new course through various old abandoned streams (dhars) of the river.

The gigantic task of bringing the river back to the original course was taken up on war footing, and 1.73 km-wide breach was finally closed on 30 January 2009. The allied flood protection works such as spurs, bedbars, slope, apron pitching, etc. were also completed by 1 May 2009. Thus, the Kosi River was again brought back to flow along its established course through the Barrage.

The story of this nature’s fury versus human grit which has been acclaimed as one of the most challenging engineering endeavours of our time has been described in this paper as a case study.