AbstractAccurate estimation of extreme flood events having a specified probability of occurrence is a key element in the planning and operation of water resources systems. Guidelines that specify a particular approach (statistical distribution and fitting technique) for flood-flow frequency determination have been introduced by a number of counlries seeking uniformity in the management of their water resources among government and private agencies. We present an expert system thet gives a general framework for choosing among distributions and among the most commonly used fitting techniques (methods for parameter estimation) for these distributions. The expert system will make it easier to see some of the advantages and disadvantages of each method. In particular, the system would be used (a) to help the user decide about the criteria of independence, homogeneity, stationarity, and outliers in the sample; (b) to help the user decide about the results of the fitting operations by providing a large number of fitting methods and statistical distributions as options; and (c) to provide graphical options.