Metagame analysis of Cauvery River dispute incorporating interannual variability in virgin runoff potential of the basin

Conflict or dispute is common, involving a mismatch of interests or deficit resources shared among the contestants. Eventually, the conflict also exists among the co-riparian states of transboundary rivers contributed by the surrounding lands. In turn, river water needs to be shared based on their deservedness and agreeable to co-riparian. In this study, the inter-state (Kerala, Tamil Nadu and Karnataka) dispute over sharing Cauvery River waters in South Peninsular India is being taken up for analysis and game-theoretic modelling. Various options available to the contending co-basin states were analyzed. Also, ‘Fair and Equitable allocations’ were derived based on the deservedness of the contender and considered one of the options on each side of the riparian in the Metagame Analysis. ‘Equity’ describes deservedness based on contribution. The two components of Fairness and Equity (F&E) includes ‘Proportionality and Egalitarianism’. The former talks about deservedness, and the second talks about that equals should be treated equally, and unequal should be treated accordingly. The options adopted by any given player must reflect the hydrologic reality of flow availability. In this regard, options were developed based on the categories of unimpaired flows given as (1) maximum (MAX); (2) upper quartile (UQ), median (MED), and lower quartile (LQ); and (3) minimum (MIN). Accordingly, separate sets of options have been proposed for each player corresponding to each of the above mentioned three flow categories of MAX, [UQ, MED, LQ] and MIN. Metagame Analysis is then used to generate equilibrium outcomes and feasible solutions for three flow categories. For example, for the flow category of LQ, the equilibrium outcome arrived is (1 0 1 0, 1 0 1, 1 0 1) with a decimal value of 725. The interpretation from this outcome: Kerala obtain its with ‘Annual irrigation requirement of 1271.43 $$\hbox {Mm}^{\mathrm {3}}$$ Mm 3 and Municipal and industrial requirement of 368.12 $$\hbox {Mm}^{\mathrm {3}}$$ Mm 3 ’. Tamil Nadu obtains its ‘Annual irrigation requirement of 12,601.0 $$\hbox {Mm}^{\mathrm {3}}$$ Mm 3 with support from Prior Appropriation Doctrine (PAD)’. Karnataka obtains its Annual irrigation requirement of 8732.9 $$\hbox {Mm}^{\mathrm {3}}$$ Mm 3 with support from Prior Appropriation Doctrine (PAD)’. This study shows that the outlined approach can indeed organize information and, in the process, facilitate a proper understanding of the conflict and also aid in deriving Fair and Equilibrium outcomes as possible candidate solutions to this conflict. Graphic abstract