PURPOSE: To enable easy and proper operation control by anticipating the rain runoff after five minutes according to the hydraulics model of a storm sewer so as to determine the number of pumps to be operated, and repeating this process to originate a pump operation plan.

CONSTITUTION: Means are provided for originating a pump operation plan regarding control in rainy weather and the rain runoff after five minutes is anticipated according to the hydraulics model 5 of a storm sewer 1 and the number of pumps to be operated is determined according to the result. This process is repeated several times to originate a pump operation plan at intervals of five minutes over a set time for anticipation. In this case, actual data are employed to anticipate rain runoff until the first period of five minutes elapses and anticipated precipitation based on rainfall forecasting is used thereafter to anticipate rain runoff. Also, means are provided for calculating the opening of a storage gate and for originating a pump operation plan regarding control in fine weather and an average amount of discharge and the water level after a predetermined time are calculated on the basis of actual data including the level of the sewer 1 and the number of pumps to be operated, etc., and of the input time of discharging. Then the target opening and the number of pumps to be operated in stored data are determined according to the result.