Abstract: The impermeability of basin, allowable water depth and drainage modulus of polder are main parameters of basin flood simulation in the HEC-HMS (The Hydrologic Engineering Center’s Hydrologic Modeling System) model under polder flood control mode.The setting of these parameters has strong impact on the simulation results. Taking Qinhuai River Basin as research area, we constructed an HEC-HMS hydrological simulation model to analyze the influence of impermeability, allowable water depth and drainage modulus on flood peak and flood volume simulation results. Results revealed that with impermeability increasing from 20% to 70%, the flood volume and flood peak of river basin in polder flood control mode displayed consistent rising trend. When the allowable water depth of polder raise, the flood volume of the basin in the polder mode was decreasing, while the flood peak was increasing. Moreover, with the reduction of drainage modulus, the flood peak and flood volume of the basin were decreasing.

Key words: HEC-HMS model, flood simulation, parameter change, polder, Qinhuai River Basin