In our country the data related to the flow volume in the watercourses is recorded in three database systems: water-gauge, limnigraph and telemetric (digital) one. In each of those systems the flow value is presented in a different way. The aim of this publication is to present how the non-compliance of the meaning and substantive difference of water-gauge data and limnigraph data influences on the example of 7 hypothetical floods determined by the Cracow method. Cracow method was initially known as Cracow Technical University Method. The received results show that the limnigraph data does not effect significantly the parameters of the hypothetical floods. In absence of the data from the telemetric system, such analysis has not be done.