With concerns mounting over the impact of climate change on Himalayan glaciers, the Ministry of Jal Shakti has released an updated atlas of glacial lakes that are part of the Ganga river basin. About 4,707 glacial lakes have been mapped in the Ganga basin. Last December, a similar inventory of glacial lakes was prepared for the Indus river basin.
For the present study, glacial lakes with water spread area greater than 0.25 ha were mapped using Resourcesat-2 (RS-2) Linear Imaging Self Scanning Sensor-IV (LISS-IV) satellite data. Based on its process of lake formation, location, and type of damming material, glacial lakes are identified in nine different types, majorly grouped into four categories.
The area mapped spans from the origin of the river to foothills of Himalayas covering a catchment area of 2,47,109 sq. km. The study portion of Ganga River basin covers part of India and transboundary region. The Atlas is available on Bhuvan portal of NRSC, ISRO.
The expected “utility” of the atlas, according to a statement from the Ministry was to create a “comprehensive and systematic” glacial lake database for Ganga River basin . The atlas could be used as reference for carrying out changes in the lakes over time, the spatial extent (expansion/shrinkage), and formation of new lakes.
The information on glacial lakes including their type, hydrological, topographical, and associated glaciers are useful in identifying the potential critical glacial lakes and consequent GLOF (Glacial Lake Outburst Flood) events. These refer to disasters whereby a deluge of water from such a lake can trigger a disaster. The Chamoli disaster of February this year was initially thought to be a GLOF event but later, scientists have concluded that it was caused by the breaking off of a mass of rock and ice.