Sequential Damming Induced Winter Season Flash Flood in Uttarakhand Province of India

204 persons were killed while two hydropower projects located in close proximity at Rishiganga (13.2 MW), and Tapoban (520 MW) were damaged in Dhauliganga flood of February 7, 2021 in the Indian Himalaya. This incidence occurred during the winter season when the discharge of the glacier fed rivers is minimal, and no rain was experienced in the region around the time of the flood. Despite discharge of the main river, Rishiganga, not involved in the flood due to damming upstream of its confluence with Raunthi Gadhera, based on field evidences massive volume of around 6 million cu m water involved in this flood is attributed to sequential intermittent damming at three different places; (i) Raunthi Gadhera was dammed first in its upper reaches, (ii) Rishiganga river was then dammed to the north of Murunna, and (iii) finally Dhauliganga river was dammed around Rini village to the upstream of its confluence with Rishiganga river. Lacking warning system only enhanced the flood-induced devastation. Legally binding disaster risk assessment regime, together with robust warning generation, and dissemination infrastructure are therefore recommended for all major infrastructure projects.