The Nepal Flood: What We Know

On 26 August 2026, a mass of rock and ice broke off the north face of Langtang Lirung, on the Nepal/Tibet border, and sent a debris flow down the Bhote Koshi and Trishuli rivers through Rasuwa and Nuwakot districts. I'm a hydropower engineer. This is an account of what's established about how the flood happened, what's still unresolved, and what freely available satellite data shows about the ground it moved through, recorded on 27 August, one day after the event. Everything here is provisional and will be revised as ground access becomes available. Chapters: 0:00 Cold Open 0:40 The seismic record 1:03 Water Levels 1:33 The route the flood took 2:52 Purepu Flood 3:11 What the satellites show 5:02 New Hazard 05:31 Climate 5:48 Where it stands 06:28 Outro Sources and data: USGS event us7000tbwb (magnitude and reclassification) ICIMOD media advisory, 26 August 2026 (gauge data, source area) Xu et al., EGUsphere preprint 2026-4065 (Purepu Glacier system, 2025) Satellite imagery: Contains modified Copernicus Sentinel data 2026; Landsat 9 courtesy of USGS/NASA. All casualty figures cited were current at the time of recording and have since changed. Corrections will be pinned in the comments as the reconstruction develops.