Inter-basin transfer megaprojects pose a decision dilemma under deeply uncertain futures: the case of Godavari-Krishna water transfers in Southern India

Globally, Inter-Basin Transfer (IBT) of water is being widely used to address water scarcity concerns, with on-going and planned projects worth $2.7 trillion. Water transfers must satisfy diverse short-term and long-term preferences of donor and recipient basins, but the extent to which IBT provides value under uncertain future water availability and demand is unclear. Here, we identify and evaluate management strategies for a proposed IBT in Southern India; a vital link in India’s National River Linking Project (IRP).

We explore five ways to transfer water that distinguish static with adaptive strategies and explore the role of information coordination between donor and recipient basins. Static (adaptive) strategies prescribe transfer volumes independent of (dependent on) system states such as reservoir levels. Static strategies include the status quo of no water transfer, a rule proposed by regional authorities and an optimized rule. The two adaptive variants are adaptive-cooperative and adaptive-noncooperative.Using a Many-Objective Robust Decision Making (MORDM) approach, we identify strategies that trade-off between flood protection, demand satisfaction, and environmental flow maintenance in the donor and recipient basins.  We stress-test these strategies under stochastically perturbed historical inflows, and deeply uncertain future climates developed using a delta change approach. In the historical period, adaptive-cooperative strategies show overall highest multi-objective performance, but their performance is significantly degraded when long-term precipitation changes by 10% - 12%. The status quo of no water transfer emerges as a viable alternative maintaining minimum performance under a large fraction of deeply uncertain futures. Our analysis suggests the importance of a rigorous evaluation of IBTs for better understanding of the relative benefits and management of such expensive infrastructure.