Abstract: To identify the sensitive parameters of a storm water management model (SWMM) and thus achieve their efficient calibration, this study develops a SWMM for the Shenzhen River basin. Both the modified Morris screening method and mutual information (M-I) method are separately used to quantitatively analyze the sensitivity of the peak flow at the drainage outlet and the average runoff coefficient of the basin to the model parameters under design rainstorms of return periods of 1 year, 10 years, and 50 years. The results of both methods reveal that for different design rainstorms, the peak flow is most sensitive to the Manning roughness coefficient and minimum infiltration rate of the permeable area, and the runoff coefficient is most sensitive to the parameters related to infiltration. However, with rainstorm intensity increasing, the sensitivity of runoff coefficients to the maximum or minimum infiltration rates manifests different trends calculated by different methods. While Morris method gives a decreasing trend, the M-I method gives the opposite.

Key words: SWMM model, sensitivity analysis, Morris screening method, mutual information method, Shenzhen River