Estimation of drought risk through the bivariate drought frequency analysis using copula functions

Ji Soo Yu; Ji Young Yoo; Joo-Heon Lee; Tea-Woong Kim

doi:10.3741/JKWRA.2016.49.3.217

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2016 Vol.49, Issue 3 Preview Page Next Page

Estimation of drought risk through the bivariate drought frequency analysis using copula functions 코플라 함수를 활용한 이변량 가뭄빈도해석을 통한 우리나라 가뭄 위험도 산정

31 March 2016. pp. 217-225

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Abstract

The drought is generally characterized by duration and severity, thus it is required to conduct the bivariate frequency analysis simultaneously considering the drought duration and severity. However, since a bivariate joint probability distribution function (JPDF) has a 3-dimensional space, it is difficult to interpret the results in practice. In order to suggest the technical solution, this study employed copula functions to estimate an JPDF, then developed conditional JPDFs on various drought durations and estimated the critical severity corresponding to non-exceedance probability. Based on the historical severe drought events, the hydrologic risks were investigated for various extreme droughts with 95% non-exceedance probability. For the drought events with 10-month duration, the most hazardous areas were decided to Gwangju, Inje, and Uljin, which have 1.3-2.0 times higher drought occurrence probabilities compared with the national average. In addition, it was observed that southern regions were much higher drought prone areas than northern and central areas.

Keywords

bivariate drought frequency analysis

copula

critical severity

drought risk

가뭄은 지속기간과 심도의 두 가지 변량으로 특징지어지는 수문사상이므로 가뭄 지속기간과 심도를 동시에 고려하는 이변량 가뭄빈도해석이 요구된다. 그러나 이변량 결합 확률분포는 3차원의 분포형태를 나타내어 실무에서 분석과 활용이 불편하다는 단점이 있다. 이를 보완하기 위해 본 연구에서는 코플라 함수를 활용하여 이변량 결합 확률분포함수를 추정한 후, 지속기간별 조건부 확률분포함수를 산정하였고, 비초과확률에 따른 임계심도를 결정하였다. 과거 극심했던 가뭄사상들을 바탕으로 95% 비초과확률에 해당하는 임계심도를 갖는 극한 가뭄사상에 대하여 수문학적 위험도를 산정하였다. 10개월 지속기간을 가지는 가뭄사상의 경우, 가뭄위험도가 가장 높은 지역은 광주, 인제, 울진으로 전국 평균에 비해 1.3-2.0배 높은 가뭄발생확률을 나타내었다. 또한, 남부지역이 중부와 북부지역보다 더 높은 가뭄 취약성을 갖는다는 것을 확인하였다.

키워드

가뭄 위험도

이변량 가뭄빈도해석

임계심도

코플라

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Information

Publisher :KOREA WATER RESOURECES ASSOCIATION
Publisher(Ko) :한국수자원학회
Journal Title :Journal of Korea Water Resources Association
Journal Title(Ko) :한국수자원학회 논문집
Volume : 49
No :3
Pages :217-225
Received Date : 2015-12-30
Revised Date : 2016-01-18
Accepted Date : 2016-01-19
DOI :https://doi.org/10.3741/JKWRA.2016.49.3.217

Journal of Korea Water Resources Association ISSN:2799-8746(Print) 2799-8754(Online) 한국수자원학회 논문집

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