Effects of Hydrologic Conditions and Reservoir Operation on Transboundary Cooperation in the Lancang-Mekong River Basin

Multiple stakeholders in transboundary river basins would benefit from cooperation, but how and why stakeholders can achieve this cooperation remains difficult to determine. This paper proposes an approach for analyzing the effect of the cascade reservoir system operation under varying hydrologic conditions on transboundary cooperation, taking the Lancang-Mekong River as a case study. The results demonstrate that the economic gains from cooperation are greater than those from noncooperation, particularly in dry years. The systematic incremental benefits of cooperation increase with the exceedance percentage, P, of the flow duration curve, indicating that the dryer the basin, the more benefits cooperation can yield. The operation policies of the cascade reservoir system in China influence the spatial and temporal streamflow patterns in the downstream Mekong River and provide substantial economic benefits to downstream stakeholders in coalitions. When China participates in the cooperation, the cascade reservoirs release more water in dry seasons, leading to hydropower loss upstream, but extra gains at the system level. An interesting free-ride phenomenon in partial coalitions is observed, illustrating the unique character of the transboundary river basin system as a continuum. The shares of the benefit for each stakeholder vary with different cooperative game methods. It is also determined that stakeholders are unlikely to reach a consensus on the preferred solution to benefit sharing, but they will not depart from the grand cooperation if one of the three proposed cooperative game-theory solutions is really implemented.