Flood events of the Pachang River, one of the major rivers in Taiwan, are modeled by extreme value distributions. Flood events are characterized by its peak, volume, duration and the time of peak. Flood volume and peak are fitted to a generalized extreme value distribution. Flood duration and the time of flood peak are incorporated into the model to detect possible trends. The results show that flood volume exhibits an upward trend with respect to flood duration, but flood peak exhibits a downward trend with respect to flood duration. There appears to be no significant trends with respect to time. Among other results, we provide estimates of return period for flood peak and flood volume, which could be used as measures of flood protection. This paper provides the first application of extreme value distributions to flood data from Taiwan.
