Bivariate Frequency of Meteorological Drought in the Upper Minjiang River Based on Copula Function

Based on the Standardized Precipitation Index (SPI) and copula function, this study analyzed meteorological drought in upper Minjiang River basin. The Tyson polygon method is used to divide research area into four regions based stations. monthly precipitation data of stations from 1966 2016 were for calculation SPI. change trend SPI1, SPI3 SPI12 showed historical dry-wet evolution phenomenon short-term humidification long-term aridification area. major events each region are counted SPI3. results show that lasted longest Maoxian region, occurrence minor was more frequent than other regions. Nine distribution functions fit marginal duration (D), severity (S) peak (P) estimated SPI3, best obtained by chi-square test. Five create a bivariate joint probability distribution, function selected through AIC, univariate return periods calculated. paper will help assess risk.