Abstract: Dynamic control of reservoir stage during flood seasons facilitates efficient water resources utilization. However, the existing dynamic control strategies typically convert meteorological forecasts into reservoir inflow conditions, and few make direct use of these forecasts of different types, particularly for the typhoon events forecasted with longer lead time. This paper describes a progressive dynamic control method that uses the forecast data of typhoon and precipitation events for a better reservoir stage control. First, we classify the precipitation events based on their underlying causes, and determine the control thresholds for each precipitation type. Then, we determine the multi-stage dynamic control water levels through historical data simulations for different precipitation types. In a case study of the Jiaokou reservoir in Ningbo, Zhejiang, China, a progressive dynamic control scheme is derived as follows. Prerelease is done at an outflow for the maximum power output if the forecasted typhoon distance exceeds 1200 km; It continues until the stage of 62.6 m is reached if the distance is in the range of 385-1200 km; It further continues up to the flood limited water level (60.18 m) if the distance is less than 385 km. Results indicate that this scheme increases average water storage by a volume equivalent to 4.6% of the annual water supply compared to historical operations, and reduces spilled water by 31% relative to conventional dynamic control. Thus, this study demonstrates the benefit of dynamic control based on the typhoon track and precipitation forecasts.

Key words: reservoir, dynamic control, progressive, typhoon tracks, prefill and prerelease, floodwater resources