Development of a Triple Drought Management Index Using Copula-Based Trivariate Frequency Analysis

Drought is one of the costliest natural disasters, causing economic, social and environmental damage worldwide. Many researchers demonstrate that climate change will make extreme weather events more intense in the future. As extreme weather events increase, the frequency and magnitude of drought are likely to increase, requiring a proactive approach to drought management. Reliability, Resilience, and Vulnerability (RRV) are used in drought risk management to assess the management of water resources under drought conditions. The RRV framework provides comprehensive analyses on the probability of success or failure of a system, the rate of recovery (or rebound) of a system from unsatisfactory conditions and quantifying the expected consequences of being in unsatisfactory conditions for extended periods. It is necessary to consider all three criteria as uncertainty increases under climate change. This study proposes a triple drought management index (TDMI) by integrating the RRV indicators. Since the RRV indicators may be dependent on each other in drought situations, a copula model was used to describe the nonlinear dependence structure. The trivariate copulas considered for this study are the Clayton, Frank, and Gumbel copulas of the Archimedean family, which are commonly used in the field of hydrology. According to the TDMI calculation, the Seomjin River basin had a maximum TDMI index value of 2.19 during the period 1992-1994. According to the classification criteria, this corresponds to a severe drought, and indeed, the area was affected by limited water supply during this period. This study proposes a model for more comprehensive drought management by incorporating the RRV indicators. It can not only determine whether a drought is occurring but also comprehensively determine the overall state of the system under drought conditions.

 

Acknowledgement: This research was supported by Korea Environment Industry & Technology Institute (KEITI) through Water Management Innovation Program for Drought (RS-2022-KE002032) funded by Korea Ministry of Environment.