Rainstorm Combination Design during the Meiyu Season: An Example from Southern Jiangsu, China

Abstract

Meiyu is a unique weather phenomenon in East Asia that affects the middle and lower reaches of the Yangtze River in China, as well as Taiwan, central and southern Japan, and southern South Korea. It typically occurs from June to July every year. Rainfall during the Meiyu season causes disasterous floods in southern Jiangsu, China. To improve the effectiveness of flood disaster planning in southern Jiangsu, an understanding of the probability of regional rainstorms during Meiyu is needed. Analytical results based on 16 symmetric and asymmetric Archimedes copula functions show that the overall performance of predicting probability using multiparametric asymmetric Archimedean copulas is better than that of single-parameter symmetric Archimedean copulas. In asymmetric Archimedean copulas, the Type II Gumbel distribution was most effective. Based on the joint rainfall distributions in the study area, a rainfall combination design method with an adjustment factor φ is proposed. Factors inherent in the adjustment factor φ (e.g., different return period design standards and increases in extreme rainfall) are discussed.