Abstract: Flood storage and detention areas play an important role in flood control in the middle and lower Changjiang River, so it is significant to study the simulation method of the flooding processes in the flood storage and detention areas.Based on the measured width and flow discharge data of the embankment failure at Tuanzhou embankment alongside the Dongting Lake in2024,the discharge process at the breach was reproduced, and the flood evolution was simulated by using a two-dimensional hydrodynamic model to analyze the temporal and spatial variations of disaster-causing factors, including water inundation depth and flow velocity.The results showed that:(1) the development of embankment failure included three stages, namely, downward scouring, lateral widening and steady discharging; the total water volume entering the Tuanzhou embankment was estimated as2.53×108m3based on the discharge process, which was basically equivalent to the water volume(2.63×108m3) back-calculated according to the reservoir capacity curve.(2) The discharge and water level processes near the breach were basically consistent with the measurements, and the maximum water level in the Tuanzhou embankment was31.955m, which was basically consistent with the measured water level(31.960m).(3) The inundation range calculated by the model was basically consistent with the range extracted based on remote sensing images.At the end of the calculation period,92.7% of the area was in severe inundation(the inundation depth >1.5m),the maximum inundation depth was about8.2m, and the flow velocity in the embankment increased first and then decreased, with the average flow velocities at each time(t=4h, t=10h,t=15h andt=20h) were0.37,0.43,0.22m/s and0.05m/s.The results can provide technical support for the risk assessment and flood control of embankment failure.