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

Fangling Qin,Ting Chen,Tianqi Ao

doi:10.3390/w13152056

Abstract

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

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Based on the locations of 4 meteorological stations, the ArcGIS geographic information platform was used to generate Tyson polygons, and the study area was divided into four regions
In order to explore the changes in drought trends in various regions, this paper uses the MK trend test method to calculate the Kendall trend statistics of the SPI1, SPI3, and SPI12 at each meteorological station

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Drought is a frequent natural disaster, which affects ecology, social economy, and agriculture to a large extent. The change of drought may be faster than the average climate change with global warming [1,2]. What is more serious is that due to the expansion of the scale of industry and agriculture, social and economic development, global warming and the rapid growth of the world’s population, the demand for water has risen sharply. The shortage of water resources has increased, and the global drought trend is obvious [3]

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Conclusion