Trends and multi-decadal variability of annual maximum precipitation for Seoul, South Korea

Abstract

Flood risk management is an important and difficult problem for the densely populated and rapidly urbanised city of Seoul, South Korea. This study characterises long-term trends and variability in the city's annual maximum daily precipitation (AMP) over multiple decades. Smoothing the time series reveals that recent decades have witnessed a steep upward trend in AMP. Continuous wavelet analysis shows that the AMP series has statistically significant power in the 32–60-year periodicity band between 1880 and 1960 (one full cycle is clearly visible in the smoothed series). This feature has an even wider scope in the annual total precipitation series, suggesting that a real oscillation exists. Four climate indices were investigated as possible explanatory variables for the AMP series using cross-wavelet analysis, but no significant coherence between the signals was found. Finally, mean AMP forecasts based on three interpretations of the past linear trend are provided for flood risk management.

Keywords:

• climate variability
• flood frequency
• multi-decadal
• trend
• precipitation
• wavelet

Acknowledgments

This research was also supported by a grant (05 InfrastructureD03-1) from the Construction Infrastructure Technology Program funded by the Ministry of Construction & Transportation of Korean government.