Flooding and Road Destruction in Eastern Nepal

Abstract

of the Sun Kosi east of Barabesi. It is unclear at the present time what happened in the Sun Kosi valley below Barabesi and Sun Kosi Bazaar; perhaps the flood waters simply continued down the river. However, in view of the morphology of the region (including the sharp bend that the Sun Kosi makes as it joins the Bhote Kosi), past episodes of flooding in the Himalaya, and the destruction caused downstream, it is most probable that the Bhote Kosi was temporarily dammed by the mudflow debris which spilled into the north-south flowing Bhote Kosi-Sun Kosi; the Bhote Kosi then backed up forming a lake behind the dam; and eventually the dam burst open, releasing the backedup waters. In any case, the result was a large flood that totally destroyed over 18 km of the Arniko Highway between the towns of Barabesi and Balephi. The inlet to the Lamasangu Hydroelectric Plant, including a dam across the Sun Kosi, was also lost. Smaller landslips along the Arniko Highway, resulting from the same rainstorm, have partially destroyed another 50 km of the road. Figure 1 shows the location of the rivers, villages, landslides, and debris dams.