Abstract: The “No.1 flood in 2017” is a regional big flood in the midstream of Changjiang River. Reservoir groups in the upper and middle reaches were dispatched jointly to cope with the severe flood situation. The discharge of Three Gorges reservoir reduced from 27 300 m³/s to 8 000 m³/s, which had been the largest compensation ever. The compensation guaranteed that the water level at Lianhuatang station did not exceed the critical stage for flood diversion. Flood forecast for Lianhuatang station is crucial for the determination of joint dispatching time and dispatching effect. In this paper we introduce the flood forecast method for Lianhuatang station, and analyze the forecast result and the causes of errors. In addition, we also summarize the difficult points in flood forecast in the aim of providing more scientific technical support for the flood prevention and decision-making.

Key words: No.1 flood of Changjiang River in 2017, Lianhuatang, flood forecast, flood control dispatching, stage-discharge relation