Image above: SkySat image of the rockslide in Rishiganga, India taken February 9, 2021. © 2021, Planet Labs PBC. All Rights Reserved.
In early February of 2021, the Chamoli district, located in India, experienced heavy rain flows, leading to flash flooding in the mountainous region. This flooding, combined with a series of interconnected events on February 7, 2021, generated an unprecedented landslide, the generation of a temporary dam in the valley system, and a subsequent breach which impacted local lives and economies. To better understand the interplay between the factors leading to this landslide, researchers from Aligarh Muslim University and the Indian Institute of Technology Roorkee used Planet satellite imagery. By reviewing PlanetScope data from before and after the event, alongside scientific case studies and published reports, the researchers were able to analyze how the weather events interacted with the unique geological formations of the mountain side to cause such an event. Their work suggests that a positive feedback system existed between an earlier winter freeze, the rapid flood, wedge rockfall in the region, and erosion in the valley system, leading to the structural instability of the mountain peak and subsequent natural disaster. Planet Dove satellites captured images of the landslide only shortly after the event, revealing a dust and debris path that could be traced by the scientists to help to determine the cause of the landslide. “There is a need to monitor such extreme hydro-geomorphic events in the vulnerable cryospheric region of Uttarakhand for prospects. The scope of real-time monitoring, analyzing and alert decimation system needs to be increased up to individual level via mobile phones and public warning systems. An alarming system relying on sensors should be employed for public awareness,” said the authors.
The full study can be found in Natural Hazards Research.
Image below: PlanetScope image of the landslide in Chamoli, India taken the day of the disaster (February 7, 2021). © 2021, Planet Labs PBC. All Rights Reserved.