A sensitivity analysis of Storm Water Management Model in a residential area

This study discussed the sensitivity of main parameters of urban storm drainage system based on Storm Water Management Model. A residential dominated catchment in Sendai city of Japan was chosen as the study area. The parameter sensitivities were considered with different rainfall condition, model spatial scale and infiltration equations. The parameters about imperviousness, roughness, initial loss and infiltration were considered. Three patterns of rainfall with same total depth were designed: single peak, multi peak and flat continuous rainfall. And the models were built up with 2 different spatial scales to evaluate the scale effect on sensitivity. The Morris method was used for sensitivity analysis. The lower and upper limits of parameter range for sensitivity analysis were set to 50% and 150% of the initial parameter value. The result showed that Imperviousness was the most sensitive parameter, afterwards were the surface Manning roughness and depression storage depth. Sensitivities of Green-Ampt and Horton infiltration parameters as well as the initial loss parameters were influenced by rainfall characteristics. These parameters were more sensitive when the rainfall were less intensive. The sensitivity of catchment roughness and conduit roughness were scale dependent. Specifically, with finer spatial resolution, the conduit roughness tended to be more sensitive than coarser resolution.