Hydrologic regionalization of watersheds. I: Methodology development

A hydrologic regionalization scheme is proposed for classification of watersheds at gauged sites. This scheme used 16 streamflow parameters estimated by a time series model to classify 94 watersheds into 6 regions by cluster analysis. The classified regions seem to be separated by physiographical boundaries, especially the two main clusters. Discriminant analysis tests the significance of the cluster difference; thus, each cluster represents one hydrologic region. Principal component analysis interprets the regional differences and similarities. The regional membership is mainly identified by the watershed variables of elevation, forest area, channel slope, and precipitation based on the calculation of the scores of canonical discriminant variates. This emphasizes the importance of the hydrologic regionalization and the identification of the specific characteristics in each region.