A two-period model is widely used to derive optimal hedging rules for reservoir water supply operation, often with storage targets as the goal to conserve water for future use. However, the predetermined storage targets adopted in the two-period model result in shortsighted decisions without considering the control of long-term reservoir operation. The purpose of this paper is to propose a new model to seek a more promising water supply operation policy by embedding the hedging rule derived from the two-period model in an optimization program for storage targets. Two modules are incorporated in the new model: the two-period model for optimizing water release decisions in each period with given storage targets and the optimization module to determine the optimal values of storage targets for connecting different periods. The Xujiahe water supply system is taken as a case study to verify the effectiveness of the proposed model. The results demonstrate that the new model is superior to others based on standard operation policy or rule curves during droughts and reduces the maximum water shortage.