Two Ways to Quantify Korean Drought Frequency: Partial Duration Series and Bivariate Exponential Distribution, and Application to Climate Change

Jeongeun Won,Moo Jong Park,Okjeong Lee,Sangdan Kim,Jeonghyeon Choi

doi:10.3390/atmos11050476

Jeongeun Won, Moo Jong Park + Show 3 more

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https://doi.org/10.3390/atmos11050476

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Journal: Atmosphere	Publication Date: May 7, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: Pukyong National University, Hanseo University

Abstract

Studies using drought index to examine return levels of drought can be classified into two approaches: univariate frequency analysis using annual series extracted from drought index time series and multivariate frequency analysis that simultaneously reflects various characteristics of drought. In the case of drought analysis, it is important to properly consider the duration, so, in this study, univariate frequency analysis is performed using the partial duration series. In addition, a bivariate frequency analysis is performed using a relatively simple bivariate exponential distribution to give a more realistic return level to major drought events in the past while reflecting the correlation between drought severities and durations. The drought severity–duration–frequency curves using each of the two frequency analyses are derived, and these curves are used to examine how the drought phenomenon currently in progress is evolving. From this, the advantages and disadvantages of the two approaches, as well as the points to be aware of in application, are discussed. Finally, using the two approaches to the proposed drought frequency analysis, the behavior of Korea’s future extreme droughts is investigated under the conditions of various future climate change scenarios.

Highlights

IntroductionDrought is difficult to quantify since it occurs over a large area over a relatively long period of time
Unlike flooding, drought is difficult to quantify since it occurs over a large area over a relatively long period of time
Studies looking at the return level of drought using the drought index can be broadly divided into two categories: Univariate frequency analysis using annual series extracted from drought index time series, and multivariate frequency analysis by simultaneously reflecting various characteristics of drought events

Summary

Introduction

Drought is difficult to quantify since it occurs over a large area over a relatively long period of time. It is very difficult to quantify drought by reflecting them properly. The most common method of quantifying drought is to use a drought index. Various drought indices have been developed by using factors such as precipitation, evapotranspiration, soil moisture, reservoir storage, and river flow rate in accordance with the purpose of use [1]. Studies examining the return level of drought from the drought index can be broadly classified into two approaches. The first is an approach that extracts an annual maximum (or minimum) series (AMS)

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