Temporal discretization of the synthetic Chicago storm

Abstract

One of the methods frequently used for the project hydrographs calculation in urban areas is the precipitation runoff transformation method. Its input function is a synthetic maximized hyetograph that it is called "design storm". Although the temporal distribution of the design storm is often expressed as a continue function, its application in runoff models needs to be discretized in time intervals that generally coincide with the computational time step. The greater the interval of time, the greater the instantaneous peak intensity attenuation, mainly in sharp maxima as the Chicago storm, that modifies the simulation results, especially in small basins and when no lineal models are applied. The greater the time interval used to define Chicago hyetograph, the greater the attenuation of the calculated peak flow. The results of the experimental basin simulation on Santa Fe city (Argentina) are obtained by the application of SWMM model (Storm Water Management Model). The temporal discretization influence of the Chicago Storm on these results is evaluated here.