In Taiwan, most of its yearly rainfall concentrates in the summer and autumn because of the particular climate and geographic characteristics. During Typhoon period, the reservoir operators often face the dilemma of maintaining more floodwater and taking the risk of failure of the dam and taking the risk of being drought if excess floodwater is released. During flood control operation, lower reservoir peak stage to ensure the safety of reservoir. After flood control operation, let the reservoir retain more water. The most difficult task of reservoir operation is to consider all the functions of the reservoir.
