Integrating nonstationary behaviors of typhoon and non-typhoon extreme rainfall events in East Asia

Extreme rainfall events in East Asia can be derived from the two subcomponents of tropical cyclones (TC) and non-TC based rainfall (mostly summer monsoons). Critical natural hazards including floods and landslides occur repeatedly due to the heavy rainfall associated with the two subcomponents, and disaster losses are increasing because global warming has caused changes in the extreme rainfall characteristics of two subcomponents. Subsequently, the frequency and intensity of extreme rainfall have reportedly become nonstationary. The majority of literature on nonstationary frequency analyses do not account for the different behaviors (stationarity or nonstationarity) of annual maximum rainfall (AMR) from the two subcomponents (PM (TC) and PM (NTC)). To carry out a nonstationary frequency analysis considering the different behaviors of the PM (TC) and PM (NTC) series, this study proposes a novel approach of integrating the fitted PM (TC) and PM (NTC) series after modeling the nonstationarity of the PM (TC) and PM (NTC) series individually. The presented results conclude that the proposed approach provides more reliable estimates than existing nonstationary approaches by reflecting the different features of the PM (TC) and PM (NTC) series. We suggest that the proposed approach provides a reasonable design rainfall in constructing hydraulics to mitigate the different nonstationary effects of two TC and non-TC rainfall extremes.