Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Estimating design floods in ungauged watersheds through regressive adjustment of flood quantiles from the design rainfall - runoff analysis method

설계강우-유출 관계 분석법에 의한 확률홍수량의 회귀보정을 통한 미계측 유역의 설계홍수량 산정

  • Chae, Byung-Seok (Department of Civil and Environmental Engineering, Hanyang University) ;
  • Lee, Jin-Young (Department of Civil and Environmental Engineering, Hanyang University) ;
  • Ahn, Jae-Hyun (Department of Civil and Architectural Engineering, Seokyeong University) ;
  • Kim, Tae-Woong (Department of Civil and Environmental Engineering, Hanyang University (ERICA))
  • 채병석 (한양대학교 대학원 건설환경공학과) ;
  • 이진영 (한양대학교 대학원 건설환경공학과) ;
  • 안재현 (서경대학교 공과대학 토목건축공학과) ;
  • 김태웅 (한양대학교 공학대학 건설환경공학과)
  • Received : 2017.05.06
  • Accepted : 2017.07.25
  • Published : 2017.09.30
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Abstract

It is required to estimate reliable design floods for hydraulic structures in order to respond more effectively to recent climate change. In this study, differences of design floods that were estimated the flood frequency analysis (FFA) and the design rainfall-runoff analysis (DRRA) were analyzed. In Korea, due to lack of measured flood data, the DRRA method is used in practice to determine the design floods. However, assuming the design floods estimated by the FFA as true values, the DRRA method over estimated the design floods by 79%. Thus, this study proposed a practical method to estimated design flood in ungauaged watersheds through regressive adjustment of flood quantiles estimated from the DRRA method. To this end, after investigating the differences between design floods acquired from the FFA and the DRRA method, nonlinear regression analyses were performed to develop the adjustment formulas for 8 large-dam watersheds. Applying the adjustment formula, the accuracy was improved by 65.0% on average over the DRRA method. In addition, when considering the watershed size, the adjustment formula increases the accuracy by 2.1%p on average over when not considering the watershed size.

최근 기후변화에 효과적으로 대응하기 위해서 신뢰성 높은 설계홍수량을 산정할 필요성이 커지고 있다. 본 연구에서는 홍수빈도해석법과 설계강우-유출 관계 분석법으로 산정되는 확률홍수량의 차이를 분석하였다. 우리나라의 경우 관측유량 자료가 부족하여 설계홍수량을 결정할 때 설계강우-유출 관계 분석법으로 산정된 확률홍수량을 이용하고 있다. 관측 유량 자료를 활용한 홍수빈도해석법의 결과를 참값으로 가정하여 분석한 결과, 설계강우-유출 관계 분석법으로 산정된 확률홍수량은 홍수빈도해석법으로 산정된 확률홍수량에 비해 약 79% 과대 산정되는 것으로 나타났다. 따라서, 본 연구에서는 설계강우-유출 관계 분석법으로 산정된 확률홍수량을 보정하는 회귀곡선식을 개발하였다. 이를 위해 우리나라 8개 댐유역의 강우와 유량자료를 획득한 후, 비선형 회귀분석을 통하여 보정식을 제안하였다. 본 연구에서 제안한 보정식을 적용할 경우, 설계강우-유출관계 분석법으로 산정된 확률홍수량보다 평균적으로 정확도가 약 65.0% 향상되었다. 또한, 유역의 크기를 고려하면, 유역의 크기를 고려하지 않았을 때보다 평균적으로 정확도가 약 2.1%p 증가하였다.

Keywords

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