Effect of rainfall distribution pattern and infiltration equation on urban flood simulation (case study: Kangan Abdossalam basin)

SWMM is one of the common models used in hydrologic and hydraulic simulations of surface runoff flow throughout urban drainage networks. As any comprehensive model, SWMM needs a wide range of parameters as its input data, which usually involve measurement inaccuracies and approximations leading to model output uncertainty. The degree of such uncertainty depends on model sensitivity to each input data. This article aims to study SWMM sensitivity to patterns and sub-models used in the simulations process. Therefore, alongside examining the effect of 5 different synthetic precipitation patterns, 4 time steps of rainfall data, 3 infiltration models and 2 routing methods on runoff peak discharge values; the sensitivity of SWMM to these patterns and sub-models was analyzed. Graphical and Correlation Analysis (CA) methods were used to analyze the model sensitivity. According to the results, the model was most sensitive to rainfall time-step in which a change from 15 min to 90 min, increased peak discharge values as 26.5 and 37.5 percent. In the next level, the model was most sensitive to infiltration methods with spearman coefficients close to 1. However, the model degree of sensitivity to rainfall different distribution patterns was variable, depending on the simulation scenarios predefined.