Indus basin water flows rose while Ganga declined: study, Pg10

Key Highlights:

• A study shows the Indus basin experienced an 8% increase in annual streamflow between 1980 and 2021.
• The Ganga basin saw a 17% reduction in streamflow during the same period.
• Increased precipitation, linked to western disturbances, drives rising river flow in the Indus.
• Intensive groundwater pumping for irrigation is the primary factor behind falling river flows in the Ganga.

Detailed Insights:

• Rising precipitation, particularly from western disturbances and variable monsoon contributions, appears to be the main driver of increased river flow in the Indus system.
• The strongest increases in the Indus system are seen in the main Indus river and its western tributaries, the Jhelum and the Chenab, while the Ravi and Sutlej experienced declines.
• In the Ganga basin, rainfall has declined by roughly 10%, while temperatures and atmospheric water demand have increased, leading to reduced river flows.
• Intensive groundwater pumping for irrigation is the dominant factor behind falling river flows in the Ganga basin, with groundwater contributing 50% to 70% of annual river flow.
• The research findings intersect with the 1960 Indus Waters Treaty (IWT), which allocates the eastern rivers to India and the western rivers primarily to Pakistan.
• In some stretches of the Yamuna and upper Ganga, the natural direction of flow between aquifers and rivers has reversed due to depleted groundwater systems.

Key Concepts Involved:

• Streamflow: The quantity of water flowing in a river or other water body.
• Western Disturbances: Extratropical weather systems that originate in the Mediterranean region and bring winter rainfall to the Indian subcontinent.
• Groundwater Pumping: The extraction of groundwater for irrigation and other uses.
• Indus Waters Treaty (IWT): A water-sharing treaty signed in 1960 between India and Pakistan, allocating the waters of the Indus River and its tributaries.