Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Development of spatial dependence formula of FORGEX method using rainfall data in Korea

우리나라 강우 자료를 이용한 FORGEX 기법의 공간상관식 개발

  • Kim, Sunghun (School of Civil and Environmental Engineering, Yonsei University) ;
  • Ahn, Hyunjun (School of Civil and Environmental Engineering, Yonsei University) ;
  • Shin, Hongjoon (School of Civil and Environmental Engineering, Yonsei University) ;
  • Heo, Jun-Haeng (School of Civil and Environmental Engineering, Yonsei University)
  • 김성훈 (연세대학교 토목환경공학과) ;
  • 안현준 (연세대학교 토목환경공학과) ;
  • 신홍준 (연세대학교 토목환경공학과) ;
  • 허준행 (연세대학교 토목환경공학과)
  • Received : 2016.04.15
  • Accepted : 2016.11.15
  • Published : 2016.12.31
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Abstract

The FORGEX (Focused Rainfall Growth Extension) method was developed to estimate rainfall quantiles in the United Kingdom. This method does not need any regional grouping and can estimate rainfall quantiles with relatively long return period. The spatial dependence formula (ln $N_e$) was derived to consider the distance from growth curve of proper population to the distributed network maximum (netmax) data using the UK rainfall data. For this reason, there is an inaccurate problem in rainfall quantiles when this formula is applied in Korea. In this study, the new formula was derived in order to improve such shortcomings using rainfall data of 64 sites from the Korea Meteorological Administration (KMA). A 42-year period (1973~2014) was taken as the reference period from rainfall data, then the formula was derived using three parameters such as rainfall duration, number of site, area of network. Then the new formula was applied to the FORGEX method for regional rainfall frequency analysis. In addition, rainfall quantiles were compared with those from the UK formula. As a result, the new formula shows more accurate results than the UK formula, in which the FORGEX method by the UK formula underestimates rainfall quantiles. Finally, the new improved formula may estimate accurate rainfall quantiles for long return period.

영국에서는 지역구분이 필요없고 상대적으로 긴 재현기간에 대해서도 안정적인 확률강우량 추정이 가능한 FORGEX (Focused Rainfall Growth Extension) 기법을 개발하여 강우자료의 지역빈도해석을 수행하고 있으며, 지역빈도해석에 적합한 모집단 성장곡선으로부터 네트워크 최대값(network maximum, netmax) 자료의 분포위치를 고려하기 위하여 영국 강우자료를 이용한 공간상관식(ln $N_e$)을 유도하였다. 이런 이유로 영국에서 개발된 공간상관식을 우리나라에 적용할 경우 부정확한 확률강우량을 산정하는 문제점이 발생한다. 이를 보완하기 위하여 본 연구에서는 우리나라 기상청 산하 유인관측소 지점 중 30년 이상의 긴 강우자료를 보유한 64개 지점의 강우자료를 이용하여 공간상관식을 유도하였다. 지점 간의 합리적인 비교를 위해 1973년부터 2014까지를 기준기간(reference period)으로 정하였고, 강우지속시간, 지점 수, 네트워크 면적 등 3가지 변수를 고려하여 공간상관식을 유도하였다. 유도된 공간상관식을 FORGEX 기법에 적용하여 지역빈도해석을 수행하였고, 기존의 영국식을 이용하여 산정한 확률강우량 값과 비교 분석하였다. 그 결과 우리나라 강우자료를 이용하여 새롭게 유도한 공간상관식은 기존의 영국식 보다 정확한 것으로 나타났고, 이를 FORGEX 기법에 적용한 결과 영국 공간상관식은 새롭게 개발한 공간상관식보다 확률강우량을 과소 추정하는 것으로 나타났다. 본 연구를 통하여 기존 FORGEX 기법에서 내포하고 있는 부정확성을 보완할 수 있고, 긴 재현기간에 대한 확률강우량을 보다 정확하게 추정할 수 있을 것으로 판단된다.

Keywords

References

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