Ganga, Brahmaputra, Indus water levels to rise by 2050: New IPCC report
In News: The Indus, Ganga and Brahmaputra river basins, which provide water to the most densely populated areas of south Asia, will see an increase in river ‘runoff’ by 2050 and 2100, according to projections by the Intergovernmental Panel on Climate Change (IPCC) in its Sixth Assessment Report on Impacts, Adaptation and Vulnerability, released February 28, 2022.
River run-off refers to water that comes into a river water system from sources such as rainfall, melting snow and groundwater.
The run-off could increase 3-27 per cent by mid-century, according to the report. It would be:
7-12 per cent in the Indus
10-27 per cent in the Ganga
3-8 per cent in the Brahmaputra
The reason behind
The increase in run-off in the upper Ganga and Brahmaputra would be due to a rise in precipitation, while in the Indus, it would be due to accelerated melting snow.
The intensity and frequency of extreme discharges is also likely to increase towards the end of the century. The future of the upper Indus basin water availability is highly uncertain in the long run due to uncertainty surrounding precipitation projections.
The run-off in the Brahmaputra, Ganga and Meghna is projected to increase by 16 per cent, 33 per cent and 40 per cent respectively under the climate change scenarios by the end of the century.
The changes in run-off in these scenarios are larger in the wet seasons than the dry season.
Extreme precipitation events are also expected to increase to a higher degree in the Indus than the Ganga and Brahmaputra basins.
The consequences
Increase in extreme precipitation events is likely to cause more flash flood events in the future.
In case of Indus, increasing temperature trend in the future may lead to accelerated snow and ice melting which may increase the frequency and intensity of floods in the downstream areas
The Ganga-Brahmaputra region also faces the threat of increased frequency of flood events.
The Ganga basin also shows a higher sensitivity to changes in temperature and precipitation. Worryingly, future flow would increase in the Central Himalayan region in Nepal, which would have ‘serious consequences downstream’.
These changes could “pose serious threats to the livelihoods” of the more than 700 million people living in the basin, many of whom depend directly on water for agriculture, forestry, fisheries and raising livestock.
The Way Forward
The findings of the study will be important in shaping climate change adaptation policy in the areas surrounding these river basins.
India could engage with the “loss and damage” process in climate negotiations. Loss and damage refers to an effort in the annual climate negotiations to create a legal framework where vulnerable countries can be compensated for losses due to climate change.
With complex global connections and wide local impacts, there’s a need for a deeper understanding the Himalayan ecosystem, its sensitivity to climate change, and better disaster preparedness.
Real-time forecasts and warnings of extreme weather must be disseminated rapidly in the most efficient way.
Enhanced monitoring of glaciers by expanding observation networks that place fully automatic weather stations on selected glaciers, developing comparison projects to examine glacier area and volumes, glacier dynamics and implementing the knowledge of these studies in detailed models of glacier hydrology to reduce the uncertainty in projections, which will lead to improved preparedness.
