Frequency analysis of nonidentically distributed hydrologic flood data

The curve-fitting method of flood frequency analysis, based on a plotting position formula, does not accommodate nonidentically distributed flood sequences. On the other hand, the methods of combining component-frequency distributions may overestimate the exceedance probability of a given flood quantile. This study develops a method for estimating the exceedance probability of a specified flood magnitude for nonidentically distributed flood sequences. The method is applied to several data sets, and its results are found to be in good agreement with observed values.