Key Message: Water consumption in downstream areas of the Indus, Ganges, and Brahmaputra (IGB) basins is projected to increase by 24%, 42% and 107%, respectively, during the 21st century.
Water use for industrial and domestic purposes is projected to increase three to seven fold. Although it is currently small compared to the volume of water used in agriculture, it will form a significant portion of total water use in future.
Mean annual water availability is likely to increase by 36-42%, 37-46% and 17-46% in the Indus, Ganges and Brahmaputra, respectively, due to an increase in precipitation that is projected consistently across climate models for all three river basins .
The increase in water availability will be stronger in the upstream parts of the three basins, which will increase the dependency of downstream water users on upstream water resources.
We estimate that the current blue water gap, based on unsustainable groundwater withdrawals, is 83 km3/year in the Indus and 35 km3/year in the Ganges, and will increase by 7% and 11% towards the end of the century. Socio-economic developments leading to increased demand are the main driver of the increasing water gap.