Review of statistical models for flood frequency estimation.

The relation between flood frequency estimates and the economic decision making process is briefly discussed and selected developments in frequency analysis are traced in tabular form. The main types of frequency analysis procedures and models are surveyed including at site, at site/regional and regional only cases. The at site/regional cases include Index Flood, Bayesian and TCEV methods. Criteria for selecting a frequency analysis procedure are discussed under two headings, descriptive ability and predictive ability. The former relates to a model's ability to preserve statistics of observed flood series while the latter relates to quantile estimating ability in a robust manner. The relative merits of different types of flood quantile estimators are discussed, beginning with at site estimators and the search for a robust at site estimator. This is followed by the principal results available about at site/regional quantile estimators. Further topics considered are regional homogeneity of flood statistical behaviour, the effect of spatial and temporal interdependence of flood magnitudes, and the detection and use of historical floods.