Managing water productivity, groundwater stress, and nexus trade-offs in the Ganga River Basin, India
2025
Amarasinghe, Upali A. | Perera, Madhusha | Sikka, Alok | Mahapatra, Smaranika | Sarangi, A.
The Ganga River Basin (GRB) is a critical hotspot of the water-food-energy-environment (WFEE) nexus in South Asia, with severe pressures from groundwater over-extraction. Currently, 81 districts face overexploitation, where groundwater consumptive water use (GWCWU) exceeds 90% of extractable resources. Furthermore, 10 more districts are overexploited, 19 are critical, and 20 semi-critical, while 107 riparian districts still remain within safe limits. Rice, wheat, and sugarcane dominate GRB’s groundwater use, accounting for 88% of withdrawals. Production surpluses—32% for rice, 74% for wheat, and 408% for sugarcane—are generated mainly from unsustainable groundwater pumping. These surpluses, however, sustain food security outside the basin through the Public Distribution System (PDS). Overexploited districts must urgently reduce groundwater use for these crops, while semi-critical areas should adopt preventive measures to avoid slipping into unsustainability. Key strategies include improving the efficiency of rainfall use (green water) and enhancing the efficiency of surface irrigation (blue water) to reduce the need for groundwater pumping. Such measures would also reduce the energy demand for pumping. However, curbing groundwater use risks food and income losses, which can be offset by raising physical water productivity (PWP, kg/m³) and economic water productivity (EWP, USD/m³). Closing yield gaps between current and potential maximum yields, combined with diversification into high-value, low-water-consuming crops, can sustain production, minimize losses, and enhance both PWP and EWP. Safe districts with adequate regulation can further exploit groundwater within sustainable limits to enhance crop production. Ultimately, enhancing water productivity and balancing groundwater sustainability with food and income security is central to stabilizing the WFEE nexus in the GRB.
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