Separation Effect of Rainfall Data Based on Parameter Estimation Methods

매개변수 추정방법에 따른 강우자료의 분리효과

  • 김경덕 (연세대학교 대학원 토목공학과) ;
  • 배덕효 (연세대학교 공과대학 산업기술연구소 선임연구원, 연세대학교 공과대학 토목공학과 조교수, 연세대학교 공과대학 토목공학과)
  • Published : 1996.02.01

Abstract

It is very important to select appropriate distributions for hydrological data in planning and designing hydraulic structures. Also, it is necessary to check whether the selected distribution reproduces the statistical characteristics of the real data. In this study, the parameters of the two- and three-parameter gamma, two- and three-parameter lognormal, Gumbel, two- and three-parameter log-Gumbel, GEV, log-Pearsonn type III, two- and three-parameter Weibull, four- and five-parameter Wakeby distributions were estimated for the rainfall data of 22 sites in Korea with 7 different durations based on the methods of moments, probability weighted moments, and maximum likelihood. And the validity conditions were checked for the estimated parameters. The separation effect for each distribution was examined throught 10,000 simulations using the estimated parameters. As results, the separation effect was the smallest: log-Pearson type III for moment method, log-Pearson type III and GEV for probability weighted moment method, and GEV for maximum likelihood method. However, it is large for the two-parameter distributions.

수공구조물의 계획과 설계에 있어서 수문자료에 대한 적정분포형을 선정하는 것은 매우 중요하며, 선정된 분포함수가 실측자료의 통계학적 특성을 잘 나타내고 있는가를 검토하는 것은 필수적인 과제이다. 본 연구에서는 전국 22개 지점, 7개 지속기간의 강우자료에 대하여 2변수 및 3변수 gamma, 2변수 및 3변수 lognormal, Gumbel, 2변수 및 3변수 log-Gumbel, GEV, log-Pearson type III, 2변수 및 3변수 Weibull, 4변수 및 5변수 Wakeby 분포를 적용하여 모멘트법, 확률가중 모멘트법, 최우도법 등으로 각 분포형의 매개변수를 추정하고, 적합성 조건을 검사하였다. 각 매개변수 추정법에 의하여 추정된 매개변수를 이용하여 10,000번 모의 발생하여 분리효과를 검토한 결과 매개변수 적합성을 고려한 경우 모멘트법에서는 log-Pearson type III 분포, 확률가중 모멘트법에서는 log-Pearson type III와 GEV 분포, 최우도법에서는 GEV 분포가 분리효과를 가장 작게 나타냈으며, 2변수 분포형의 경우 모두 분리효과가 크게 나타났다.

Keywords

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