Analysis of the Runoff Calculation Parameters Sensitivity in SWMM

The selection of SWMM model parameters greatly affects the accuracy of the simulation results. Under different terrain slopes and rainfall intensities,the sensitivity of the parameters in SWMM runoff calculation is different. On the basis of qualitative analysis,some potential sensitivity parameters are selected for further quantitative analysis. Three catchments with different terrain slopes in the Lianghe Area of Jiujiang City are selected,combined with different levels of rainfall conditions,with improved Morris Method used to output the total runoff and peak flow as the output parameters. The（pervious and impervious）surface roughness,rainfall runoff infiltration parameters and conduit roughness have carried on the analysis and calculation of the sensitivity of parameters. The results show that with total runoff as output parameter,surface roughness and infiltration parameters are more sensitive when there is rainstorm in the gentle slope area. With the runoff peak as an output parameter,conduit roughness is the most sensitive parameter,and the sensitivity of surface roughness under different slopes and different rainfalls is complicated and variable.