Revisiting quantitative water-sharing frameworks in transboundary river treaties: towards sustainable water management in south Asia

Transboundary rivers are vital sources of freshwater globally, yet managing these shared waters poses significant challenges, including geopolitical tensions, unilateral water infrastructure development, and rising water demands. South Asia exemplifies these issues, with transboundary river treaties predominantly relying on quantitative/volumetric water-sharing frameworks for basin management and conflict resolution. This study critically examines key treaties, specifically the Indus Waters Treaty (IWT) between India and Pakistan and the Ganga Water Treaty (GWT) between India and Bangladesh, highlighting their strengths, limitations, and post-treaty complexities through a quantitative water-sharing lens. The analysis shows that a narrow focus on ‘partitioning of river/flow’ (quantitative water-sharing) within these treaties frequently fails to address critical factors such as dry-season flow variability, climate-induced risks, ecological requirements, benefit-sharing opportunities and escalating water demands. These gaps contribute to mistrust, geopolitical tensions, and treaty unsustainability despite their relative success. The study underscores the need for a more comprehensive framework that integrates quantitative allocation with qualitative principles, including equitable and no-harm approaches to water-sharing and benefit-sharing. Lessons from the IWT and GWT offer valuable guidance for future negotiations on the Tista/Teesta River between India and Bangladesh, emphasizing cooperative, adaptive and resilient strategies for sustainably managing South Asia's critical transboundary water resources.