Author(s): Jeongeun Won; Jiyu Seo; Sangdan Kim

Linked Author(s): Jeongeun Won, Jiyu Seo, Sangdan Kim

Keywords: EDDI; Non-stationary; Log-logistic distribution; Drought

Abstract: Climate change requires a review of the drought index as well as the definition of drought. This is because some statistical characteristics, such as the long-term average of climate, can change over time. Most studies related to the non-stationary drought index have been focused on drought caused by lack of precipitation, and relatively few studies on non-stationary related to the evapotranspiration-related drought index have been conducted. In this presentation, the Non-stationary Evaporative Demand Drought Index (NEDDI) will be described for a stable and robust quantification of drought characteristics in a changing environment. The proposed index is based on a non-stationary log-logistic probability distribution, which assumes that the location parameter of the probability distribution is a function of time. The Markov-Chain-Monte-Carlo algorithm is used to estimate the optimal parameters of the stationary and non-stationary distribution. Non-stationary and stationary EDDI (i.e, NEDDI and SEDDI, respectively) are calculated using the monthly reference crop evapotranspriation obtained by the Penman-Monteith method in the period of 1981-2019. The results show that the non-stationary log-logistic distribution is superior to the corresponding stationary distribution. Acknowledgement This work was supported by Korea Environment Industry & Technology Institute(KEITI) through Smart Water City Research Program, funded by Korea Ministry of Environment(MOE)(2019002950004)

DOI: https://doi.org/10.3850/IAHR-39WC252171192022776

Year: 2022