[Objective] To provide technical support for the precise regulation of upstream and downstream floods， the scientific arrangement of excess flood volume management， and the timely organization of emergency evacuation， we construct a risk assessment system for the operation of flood storage and detention areas （FSDAs） to accurately evaluate their dynamic operational risks. [Method] We construct an operational risk assessment system for FSDAs based on the coupling of Remote Sensing （RS） and Geographic Information Systems （GIS）. Combined with a two-dimensional hydrodynamic model and a set of operational schemes based on flood diversion volumes， the flood routing process at various stages was simulated. The dynamic risk characteristics of FSDA operation， specifically the “flood diversion volume-water level-loss-population relocation” relationship， were extracted. The Honghu Lake East Sub-block FSDA was selected as a typical case for risk analysis. [Result] （1） There is a strong linear relationship between the flood diversion volume and the average water level in the Honghu East Sub-block FSDA. For every 0.5 billion m³ increase in flood diversion volume， the average water level rises by 0.57 m. （2） The variation of various risks with flood diversion volume is comprehensively affected by loss rates and land cover distribution. Direct economic losses in this area increase most rapidly when the flood diversion volume ranges from 2.0 to 4.5 billion m³， while indirect economic losses and relocated populations grow fastest during the initial stage of flood diversion （volume <0.5 billion m³）. （3） When the flood diversion volume reaches 2.0 billion m³， the entire area is inundated， requiring the complete relocation of 183 700 people. When the volume exceeds 2.5 billion m³， the economic loss structure shifts from being dominated by indirect losses to direct losses， with secondary and tertiary industry losses stabilizing at 980 million RMB. At a flood diversion volume exceeding 3.0 billion m³， the fishery output value in the area is completely lost， amounting to approximately 3.6 billion RMB. At a volume of 6.0 billion m³， the direct and indirect economic losses are approximately 17.36 billion RMB and 6.55 billion RMB， respectively. [Conclusion] The dynamic risk assessment method established in this study can be extended to other FSDAs. The dynamic correlation characteristics of “flood diversion volume-water level-loss-population relocation” can simulate in real-time the changes in inundation extent， economic losses， and population risks under different diversion schemes. This provides a quantitative basis for selecting the timing and magnitude of flood diversion， supporting refined trade-offs in cross-regional flood volume allocation. However， the nighttime remote sensing and population distribution data used in this study have relatively low accuracy， making it difficult to apply the method to smaller FSDAs. Future research should focus on improving the accuracy of fundamental data.