Local sensitivity analysis for urban rainfall runoff modelling

Sensitivity analysis (SA) is a crucial procedure for parameter identification and uncertainty analysis. Local sensitivity analysis using Morris screening method was carried out for urban rainfall runoff modeling based on Storm Water Management Model (SWMM). The most sensitive parameter for runoff depth of three rainfall events all was the percentage of imperviousness, with sensitivity indices of 0.88, 0.98 and 0.43 respectively. In comparison, sensitivity indices (Morris) ranking for peak flow varies of rainfall events with different rainfall intensity, namely, the most sensitive parameter was conduit Manning coefficient for the rainfall event with the largest rainfall intensity, whereas the most sensitive parameter was %zero-Imperviousness for the rainfall event with the lowest rainfall intensity. Additionally, sensitivity indices rankings of parameters especially with respect to the infiltration rate of SWMM model also relates greatly to the rainfall intensity. Sensitivity analysis was used to identify the important parameters for runoff depth and peak flow, which proved to be a beneficial tool to aid for the calibration and uncertainty analysis of SWMM model.