The formation of groups for regional flood frequency analysis

A new technique is developed for identifying groups for regional flood freq uency analysis. The technique uses a clustering algorithm as a starting poi nt for partitioning the collection of catchments. The groups formed using t he clustering algorithm are subsequently revised to improve the regional ch aracteristics based on three requirements that are defined for effective gr oups. The result is overlapping groups that can be used to estimate extreme flow quantiles for gauged or ungauged catchments. The technique is applied to a collection of catchments from India and the results indicate that reg ions with the desired characteristics can be identified using the technique . The use of the groups for estimating extreme flow quantiles is demonstrat ed for three example sites.