Sensitivity Analysis of Urban Runoff Simulation Parameters in Velenjak Watershed, Tehran: Application of VARS, Sobol and Morris Methods

Integrated management of urban runoff is a key factor in the sustainable development of urban infrastructures. To do this, urban runoff modeling and flood prediction are necessary. In this paper, the Velenjak catchment in the Tehran city is selected as the study area and the SWMM model is used for simulating the rainfall-runoff process. Spatial and temporal variations of the model parameters are usually main sources of uncertainty which may affect the results of the simulation model. The purpose of this paper is to identify the parameters that are more influential and contribute to variability of model response and identify the impact of each one of them on the model outputs. Differnet measures are used to evaluate the model performance in reproducing observed streamflow time series based on variations of the model parameters. In this paper, fifteen parameters of SWMM model are considered and sensitivity analysis is performed using three methods of VARS, Sobol and Morris and the results were compared. Based on the results, six of these parameters are identified as the most effective parameters.