Climate change impact on glacier retreat and its social impact on livelihoods in Ganges River Basin, India

Glacial density varies across Himalayas, maximum in the Sutlej and Tista basin and moderate in Jhelum and Bhagirathi basin, while least density is in Arunachal Pradesh basin. Most of the glaciers are simple type, but some glaciers are bigger in size and composite in nature. The impact of global warming is perhaps already upon the Himalayas. In all these areas the orographic snowline is often a little higher than regional snowline. In the Himalayas the main source of moisture which feeds the glaciers comes from three sources as Southern monsoon, Northwestern disturbances and Local convection currents. Gangotri glacier, situated in the Uttarkashi District of Garhwal Himalaya, has been receding at the rate of 10-30 metres per year over the second half of this century. While the rate of retreat was nominal between 1935 and 1956, it started to increase rapidly after that. Present study made by the availability of GIS, Image Processing and Digital Data Sets have made the task of runoff modeling easier on the regional and local scenario. Investigation shows that spatial distributions of survival index based on relief area gradient and elongation index has least climate sensitivity of the glaciers situated in the Bhagirathi basin in Ganga headwater. In a high mountain environment the influence of certain topographic variables varying greatly. Elevation is one of the variables that have been identified as having a positive effect on snow depth and other factors those influence snow accumulation and the snowpack also computed for relational study. Results shows that the rate of retreat of each glacier varies depends upon their geophysical location and its glacial dynamics. Many glaciers shows the fast retreat in 1970s, 1980s and 1990s and the same glaciers shows the slow retreat and some glaciers are stable after 2000. In the last 13 years, the glacial channel feeding the Ganges river has shifted 20 metres and has now changed track and the volume of water too is shrinking rapidly. Due to the rise in temperature, the river flow will increase by 20 per cent initially because of more snow melt. But, ultimately, the flow will decrease by 20 per cent. Similarly, many parts of the ridge formed by rocks and debris over centuries have completely disappeared. Pilgrimage to Gangotri is an age-old tradition, but tourism as a modern phenomenon was introduced in the seventh decade of the last century. Unfortunately, tourism has developed in an unplanned manner, resulting in haphazard building construction, drainage systems, and garbage heaps in Gangotri region. In only a few short years of unplanned development, Gangotri itself has become yet another congested Himalayan town. Ganges provides water for drinking and farming for more than 500 million people. Most people do not really understand that the drinking water comes from sources like the Himalayan Gangotri glacier, and in the coming years there is a high livelihood that water shortages will ensue due to melting of these glaciers.