On February 7 of this year, the Chamoli district in the Uttarakhand region of India experienced a humanitarian tragedy when a veritable wall of rock and ice collapsed and formed a debris flow that barreled down the Ronti Gad, Rishiganga, and Dhauliganga river valleys. The massive slide, caused when a wedge of rock carrying a steep hanging glacier broke off a ridge in the Himalayan mountain range, and the resulting debris flow, led to the destruction of two hydropower generating facilities and left over two hundred people dead or missing.
A self-organized coalition of fifty-three scientists came together in the days following the disaster to investigate the cause, scope, and impact of the flood and landslide. Their study, which analysed satellite imagery, seismic records, and eyewitness videos to produce computer models of the flow, was published online today in the journal Science.
Lead author Dr. Dan Shugar, PhD, associate professor in the Department of Geoscience at the University of Calgary used high-resolution satellite imagery provided by MAXAR, PlanetLabs, and CNES to determine the cause of the Uttarakhand disaster. While initial suggestions pointed to a glacial lake outburst flood, Shugar confirms that there are no glacial lakes of any size large enough to produce a flood anywhere near the site.
"High resolution satellite imagery used as the disaster unfolded was critical to helping us understand the event in almost real time," he says. "We tracked a plume of dust and water to a conspicuous dark patch high on a steep slope. This was the source of a giant landslide that triggered the cascade of events, and caused immense death and destruction."
The paper provided satellite evidence that previous large ice masses had been dislodged from the same ridge and struck the same valley area in recent years. The researchers suggest that climate change is contributing to such events happening more frequently, and that the greater magnitude of the latest disaster is an argument in favour of avoiding further developments in the area.
Department of Science and Technology, Government of India European Space Agency CCI programme and EarthExplorer10, European Space Agency Glaciers CCI, Future Investigators in NASA Earth and Space Science and Technology, ICIMOD core funds, Natural Science and Engineering Research Council, NASA Cryosphere, NASA High Mountain Asia Team, NASA Interdisciplinary Research in Earth Science, Roshydromet R&D Plan, Swiss Agency for Development and Cooperation, Swiss National Science Foundation, Swiss Federal Excellence Postdoc Award