Causes and Consequences of Rishiganga Flash Flood, Nanda Devi Biosphere Reserve, Central Himalaya, India

A catastrophic flash flood in the Rishiganga catchment, part of India's Nanda Devi Biosphere Reserve, was triggered by the unexpected dislocation of a massive rock mass (540 m wide and 720 m long) during winter—a first-of-its-kind event. The disaster, which devastated areas like Raini, Tapovan, and Vishnuprayag, raised critical questions: why did it occur in winter, and where did the debris and water originate? Field observations revealed that the flood was caused by the sudden failure of a rock slope, releasing slurry material that overwhelmed the valley. This study provides unprecedented insights into the mechanisms behind such extreme events, challenging prior assumptions about seasonal stability in high-altitude regions.

Mehta, M., Kumar, V., Sain, K., Tiwari, S. K., Kumar, A., & Verma, A. (2021). Causes and Consequences of Rishiganga Flash Flood, Nanda Devi Biosphere Reserve, Central Himalaya, India. Current Science, 121(11), 1483. https://doi.org/10.18520/cs/v121/i11/1483-1487