LAUSR

Regional frequency analysis (RFA) based on L-moments is widely used in the analysis of hydrological process. However, L-moments are defined by order statistics from a stationary distribution and thus theoretically good properties of RFA do not hold under a nonstationary distribution. In this study, a procedure was proposed for an RFA based on L-moments for nonstationary hydrological processes. The proposed method uses a distribution-free de-trended method to apply the conventional RFA based on L-moments. The conventional and the proposed RFAs for annual maximum precipitation in South Korea were compared, and the simulation results indicated that the proposed RFA could provide proper information regarding heterogeneity in a nonstationary distribution. The estimated results of return levels, the median in the nonstationary RFA, were higher than in the conventional RFA.