Nepal: rapidly building a data map to assess the damage for the government

The flood in Nepal that came down the Bhote Koshi and the Trishuli on 26 August took many lives. As Nepalis contend with this tragedy, triggered by a glacier collapse of the kind a warming Himalaya makes more frequent, the government is already working to assess the damage and guide reconstruction.

Nabin, one of our co-founders, is Nepali, and he landed in the country on the day of the flood. He approached the government, offering VIDA’s support. Within a day our team had built a workspace covering the affected area, and
that same afternoon he was in a room with the Finance Minister, Dr Swarnim Wagle, and his core team, who needed to assess the scale of the economic damage. The analysis draws on VIDA’s own settlement and infrastructure data and algorithms, local damage reports and high-resolution satellite imagery from before and after the event, so that each structure is classified individually against the flood trace, rather than inferred from models and presented in reports. The Ministry of Finance has free access and uses it daily.

Across the worst-hit reaches, from the border down through the upper Trishuli, the assessment counts 7,540 buildings (2,668 destroyed outright) and 118 km of road damaged, 70 km of it gone. Of 50 bridges surveyed on the ground, 38 were damaged and 35 washed out. On the energy side, 13 operating hydropower assets were hit, 268 MW in total, with a further 389 MW under construction also damaged. Two downstream areas are still to be delivered, so these figures will rise.

An additional, often uncounted economic loss is productive land. Some 65 km2 of valley floor, along 25 separate reaches of the two rivers, is now boulder field and river channel, including roughly 1,800 hectares that were cropland.

Relief, repair budgets and reconstruction plans all depend on knowing quickly what was lost, and on every ministry and donor working from the same numbers. That is the part we could help with: a shared map, built in days, where new layers and local reports are added as they arrive and each figure traces back to the imagery behind it. The work was offered rather than sold, and the data stays with the government.