Rainfall in eastern river basins down 20% since 1951: Study on water availability in Indus river system

This study highlights critical changes in hydro-climatic conditions impacting the Indus River Basin, a key topic in Physical Geography. The study notes a significant 20% precipitation decline in the eastern rivers (allocated to India) but relative stability in the western rivers (allocated to Pakistan). The study emphasizes that these are largely natural variabilities, reflecting how climate change directly alters regional hydrology. Furthermore, it points to severe groundwater depletion in the Sutlej and Ravi sub-basins, potentially linked to anthropogenic factors like intense agricultural practices. This disparity in water availability creates a geographic rationale for revisiting established water-sharing mechanisms, as the original assumptions regarding basin yield and flow are no longer valid. For Mains, understand the geographic distribution of the Indus system and how changing precipitation patterns threaten regional water security.

The findings are pivotal for India's diplomatic stance regarding the Indus Waters Treaty (IWT), brokered by the World Bank in 1960. Under the treaty, India has unrestricted use of the eastern rivers (Ravi, Beas, Sutlej), while Pakistan receives the waters of the western rivers (Indus, Jhelum, Chenab), subject to certain Indian rights for non-consumptive uses. India recently issued notices to Pakistan seeking to review and modify the treaty, citing 'fundamental and unforeseen changes in circumstances' (a principle in international law known as rebus sic stantibus). India argues that population pressure, clean energy needs, and climate-induced water scarcity necessitate an update. Furthermore, India has linked the treaty's operation to cross-border terrorism, declaring it 'in abeyance' following attacks. This intertwining of environmental data with geopolitical strategy is a crucial dynamic for UPSC, demonstrating how climate change acts as a threat multiplier in bilateral relations.

The study provides empirical evidence of the impact of climate change on critical transboundary water resources. The 'pronounced decline' in annual inflows to major Indian reservoirs like Pong, Bhakra, and Thein (up to 34% in Pong) directly threatens agricultural and energy security. This necessitates a shift towards climate-resilient water management. The study underscores that treaties designed in the mid-20th century may lack the flexibility to handle modern hydro-climatic realities. This raises questions about the long-term sustainability of the IWT and highlights the need for incorporating climate change adaptation strategies into transboundary water agreements. For Prelims, note the specific rivers allocated to each country and the dams mentioned. For Mains, analyze how climate change necessitates the evolution of static international environmental agreements.