FREQUENCY ANALYSIS OF PAST AND FUTURE EXTREME RAINFALL EVENTS IN TAIWAN USING d4PDF

Abstract

 Taiwan has been devastated by water-related disasters during the wet season and will face more challenges under climate change. The uncertainty of future projections of extreme rainfall events is primarily derived from the internal climate variability. The d4PDF, especially at a 20-km resolution, has the potential to assess the impact of climate change on catchment-scale hydrologic extremes in Japan. The present study first compared the probability plots of annual maximum basin-averaged rainfall derived from rain gauge observations and d4PDF in four major river basins in Taiwan. In three out of the four catchments, d4PDF was in good agreement with observations, showing its overall applicability in Taiwan. For the other basin with large bias, we applied three bias correction methods to explore robust bias adjustment. Based on raw or corrected d4PDF, we reevaluated the return period of basin-averaged rainfall in Kaoping river basins during record-breaking events that caused severe water-related disasters in Taiwan and estimated it to be 120–125 years. This evaluation has not yet been achieved with limited and sparse observational data. Finally, the d4PDF 4-degree increase experiment data were analyzed, which showed a clear and common rate of increase in the rainfall amount of 10–40% at all the four river basins in Taiwan.