Abstract: This paper develops a flood control operation model for the middle and lower Ganjiang River that has a complicated flood control system comprising reservoirs, navigation-power junctions, and flood diversion and storage areas, with an objective to maximize the reduction rate of flood peaks at flood control cross sections. This model optimizes the system’s flood control operation using a dynamic programming-progressive optimization algorithm based on a discrete neighborhood, and its results are compared with those of conventional flood control operation, through a case study of the 1961 typical floods and the design floods of 50-, 100- and 500-year return periods. The results show that the optimized operation significantly reduces the flood peaks at the flood control sections to ensure the safety of downstream areas. And the cascade reservoirs and flood diversion area play an important role in the flood-control system of the Ganjiang basin, and the effect of navigation-power junctions is very limited. For the 1961 typical floods, operation of the navigation-power junctions can reduce the peak stage of the Xiajiang reservoir to a certain degree, helping enhance the reservoir safety of flood control.

Key words: flood control and disaster mitigation, joint flood control operation of reservoirs, dynamic programming-progressive optimization algorithm, navigation-power junctions, flood diversion and storage area, middle and lower Ganjiang River