Summary:

The Chomicz model of 1953 for DDF curves, used in Poland mainly as a comparative model, is based on not quite adequate data and the approach presented by Chomicz was not substantiated enough, which raises serious doubts on the correctness of the method. Of course, the scarcity and relevance of the then data bases should be taken into account. However, independently of that problem, there are substantial reservations about the correctness of the design rainfalls developed by Chomicz for exceedance probabilities 10%, 20%, 50% and 100%. The most significant reservation concerns the correctness of the method of extending measured rainfall depth over its measured duration. The method can hardly be accepted, because it assumes that that the greatest rainfall interval intensity occurs in the end of the rainfall event, which is not supported by observations. Moreover, the number of extended rainfall depths, i.e., the number of semi-empirical values, used to develop the model of design rainfall, increases strongly with rainfall duration doubling the number of original data in the extreme case of the longest duration of 180 minutes. Also, no rationale is given for adopted criterion for the time limit of rainfall extension over the measured duration.