https://civilsocietyonline.com/environment/from-avalanche-to-disaster-in-chamoli/
Ton February 7. the Rishiganga in Uttarakhand suddenly turned virulent. Laden with boulders, water and ice it crashed through its banks in Chamoli district causing an unexpected flash flood. Had there been no barrier in the path of the flood, it would have entered the larger Alaknanda Valley and gradually petered out as the bed slope decreased. The damage would have been minimal.
The barriers: a bridge across the Rishiganga, the small 13.2 MW Rishiganga hydroelectric project.
and then in the larger Dhauliganga (West) river the barrier was 520 MW Tapovan-Vishnugad dam.