Most models in flood statistics, as well as other statistical models in hydrology, are based on the assumption of homogeneity of the sample. This means that the events in the sample should come from the same population or have the same origin. Violations of this assumption can lead to errors in the estimation and thus, for example, to overestimates or underestimates of critical flood probabilities, which are used, among other things, for the dimensioning of flood protection measures.
