水工学論文集第56巻A real-time runoff prediction system based on the Kalman filter theory using a distributed runoff model incorporating dam reservoir operation is extended to apply a basin with multiple dam reservoirs. A reservoir operation modeled with a function of inflow, outflow and reservoir storage is represented by a linear function of state variables using the statistical linearization method, which is incorporated into an entire state update vector equation composed of river discharges, dam inflows, outflows and storages in a distributed hydrologic system. An application to the Kizu River basin with five dam reservoirs successfully shows updating of state variables, which realizes fully distributed forecasting.