To speedily suppress a hunting phenomenon at the time of hunting a water storage level.
When a hunting state is detected by the change of the measurement value of a water level meter 24, a target discharged water quantity (a) corresponding to the water storage level A and a target discharged water quantity (b) corresponding to a water storage level B are selected from a constant water level table 40. Then, time required for hunting is measured in a process where the water storage level changes between the water storage levels A and B. The target water discharge quantity (a) is quantized based on measured time and the selected target water discharge quantities (a) and (b) and the lack quantity of target water discharge quantity (a) is obtained in a target water discharge quantity quantization part 42. Target water discharge quantity (a) selected in the target water discharge quantity selection part 38 is corrected by lack quantity. The opening of a gate 18 is adjusted in accordance with corrected target water discharge quantity.
SAITO TERUAKI
SHIKADA TORU
HITACHI INF & CONTROL SYST