The purpose of this paper was to carry out regional drought frequency analysis in Taiwan. First, a standardized precipitation index (SPI) was used to define droughts. Then a self-organizing map (SOM) was used to group the rain gauges into specific clusters. The two-dimensional density map shows the rain gauges can be grouped into six clusters. Moreover, the L-moment based discordancy and heterogeneity measures were used to test whether clusters may be accepted as homogeneous. The results showed the six clusters were sufficiently homogeneous. Then,the goodness-of-fit measure was used to select the best regional probability distributions of droughts.Finally, the drought magnitudes, drought intensities, and drought durations with various return periods for each cluster were estimated. The results provide a reference for the future design of hydraulic
structures in Taiwan.
Key Words : Regional drought frequency analysis,standardized precipitation index, self-organizing map, L-moment.