A global river discharge simulation is conducted in order to enable global scale assessment of adaptation measure for the change in hydrological cycles associated with climate changes, taking into account the operation of 500 individual reservoirs. The operating rule for each reservoir is estimated by newly developed algorithm and available global datasets since actual operating rule is not published globally. In this algorithm, reservoir operation is categorized into ‘irrigation purpose’ and ‘non-irrigation purpose.’ The latter decreases inter-annual and seasonal fluctuation of discharge, and the former, in addition, supplies irrigation water to meet the demand in downstream. The simulation result is validated with observed data in three reservoirs in three basins, and judged sufficient for global study. Finally, the impact of reservoir operation on river discharge is assessed globally, by comparing RES simulation, global river discharge simulation with reservoir operations, and CTRL simulation, without operations. The result indicates that reservoir operations increase by 4-43 % of monthly discharge into oceans in maximum (the world ocean is divided into eight oceans), decrease by 1-7 %.
Global river discharge simulation, reservoir operation, TRIP, Global crop calendar, Global irrigation water demand