The steps to produce a Chicago design storm Hyetograph are:

  1. Select a design storm duration.
  2. Select a time step. The time step size should not be less than the minimum duration that was used when determining the IDF curves. For the Canadian IDF curves, step size should be at least 5 minutes. It is recommended that the step size should be about 10 minutes.

If the parameters a, b, c and r for the Chicago design storm are not known they should be determined.

The instantaneous rainfall intensities at the different time intervals from the peak intensity are computed.