Hydrological Drought Analysis Using Clayton Copula Under Climate Change

초록

Recently, in Korea, occurrences of floods and droughts have been increased due to climate change. Korean government intends to develop assessment techniques for the evaluation of climate change effects on flood and drought disasters and also for the reduction and prevention of flood and drought disasters for public security. In this study, we estimated quantitative effect of climate change on drought. For this, we used the observed runoff to apply and evaluate hydrological droughts in different levels, and induced drought events to analyze drought frequency in conventional way. Analysis of the relationship between drought variables such as drought duration and drought severity was performed and drought frequency analysis using Clayton copula theory was performed. Then the results from frequency analysis by conventional single variable and copula theory were compared. Also, joint probability was used to analyze return period of droughts and severity-duration-frequency(SDF) curve was constructed. We simulated the climate data using SRES A1B scenario and KMA RCM climate model and the future runoff from a rainfall-runoff model using the climate data. This study analyzed the future droughts using the future runoff and joint probability for the assessment of the effects of climate change on droughts. As the results, the frequency analysis of Clayton copula based joint probability fitted better than that of conventional way to the tail of drought distribution. We also found that the future droughts from the drought analysis under climate change will be severe. And the methods suggested in this study could be used as the guideline of drought analysis. Acknowledgement: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No.2011-0028564)