CHANDIGARH: Melting glaciers, depleting ground water level and erratic Monsoon are going to turn the Ganaga and the Brahmaputra rivers into seasonal rivers. The change will affect farming, livelihoods ad the hydro power sector besideas causing floods downstream, a new multi-national study by researchers in Indore, Roorkee, Delhi, Bengaluru, Ahmedabad and Nepal have found.
It warns that nearly a billion people who depend on the Indus, Ganga and Brahmaputra river basins for life and livelihood are threatened by melting of glaciers in Himalaya-Karakoram mountains.
According to the study, Jammu and Kashmir and Ladakh, the states of Himachal Pradesh and Punjab and parts of northern Haryana and Rajasthan lie within the Indus River basin. Uttarakhand, Delhi, the rest of Haryana, Uttar Pradesh, Bihar, Jharkhand, West Bengal and large parts of Rajasthan and Madhya Pradesh lie in the Ganga basin. Sikkim and Arunachal Pradesh, and most of Assam, Meghalaya and Nagaland lie within the Brahmaputra basin. The affected persons amounts to nearly 13 per cent of the global population in 2021. It is found that Himalayan glaciers are receding rapidly and that many could melt entirely by 2035. What happens if Gangotri Glacier that supplies 70 per cent of the Ganges flow during dry season disappers? One may imagine its consequences, says Ritesh Arya, international renowned Geologist.
The study states that the basic runoff of rivers in the Himalaya-Karakoram comes from snow and glacier melt and base flow from groundwater. Half the ice in the Himalayan region is held in glaciers. Global heating, which is affecting glaciers, snowfall as well as rainfall patterns in the region, will have downstream consequences on the river basins. The study projects that there would be an increase in glacier melt, total river runoff and flows during different seasons until the 2050s.
According to the study, the river basins of the region cover an area of 2.75 million square km having an area of 577, 000 sq.km and an installed hydropower capacity of 26, 432 MW. The change in climate will turn these life-line rivers into seasonal rivers, it in turn will afftct farming, livelihood and hydropower to economy. The Ganga is the largest source of surface water for irrigation and major source of water for the 407 million people living in the Gangetic Basin.
The estimated contribution of ice and snow melt in the total Indus river runoff ranges between 21-40 per cent and 22-49 per cent, with estimates varying owing to different methodologies, modelling and the time period considered for each study, past research has shown. In contrast, in the upper Ganga basin, combined snow and ice melt accounted for 20 per cent of total runoff while rainfall and groundwater contributed 66 per cent and 14 per cent, respectively, states the study.
Glacial melt is already changing water regimes of the Himalayan rivers and some of the immediate effects are seen in terms of drying up of springs, which are the main source of drinking water for people in the mountains, climate scientist Anjal Prakash said. "The mountain communities and people living downstream are more prone to climate risks and the incidence of such climate-related disasters has been increasing in the region in the past two decades. These would greatly affect the people as Hindu Kush-Himalayas is one of the most densely populated and poverty-stricken mountain regions of the world and any small climate changes will affect a large proportion of people, " said Mr Prakash.
Expanding observation networks at higher altitudes; establishing fully automatic weather stations at higher altitudes to monitor temperatures and rainfall; and developing projects to study glacier area and volume were some of the recommendations made in the paper. It also suggested a multinational collaboration equivalent to NASA's (National Aeronautics and Space Administration) polar-oriented Icebridge mission which involves airborne survey of the polar ice.