Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Using asymptotic curve number regression method estimation of NRCS curve number and optimum initial loss ratio for small watersheds

점근유출곡선지수법을 이용한 소유역 유출곡선지수 산정 및 최적 초기손실률 결정

  • Yu, Ji Soo (Department of Civil and Environmental Engineering, Hanyang University) ;
  • Park, Dong-Hyeok (Department of Civil and Environmental Engineering, Hanyang University) ;
  • Ahn, Jae-Hyun (Department of Civil Engineering, Seokyeong University) ;
  • Kim, Tae-Woong (Department of Civil and Environmental Engineering, Hanyang University (ERICA))
  • 유지수 (한양대학교 대학원 건설환경공학과) ;
  • 박동혁 (한양대학교 대학원 건설환경공학과) ;
  • 안재현 (서경대학교 공과대학 토목건축공학과) ;
  • 김태웅 (한양대학교 공학대학 건설환경공학과)
  • Received : 2017.07.06
  • Accepted : 2017.09.26
  • Published : 2017.11.30
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Abstract

Two main parameters of NRCS-CN method are curve numbers and intial loss ratio. They are generally selected according to the guideline of US National Engineering Handbook, however, they might cause errors on estimated runoff in Korea because there are differences between soil types and hydrological characteristics of Korean watersheds and those of United States. In this study, applying asymptotic CN regression method, we suggested eight modified NRCS-CN models to decide optimum runoff estimation model for Korean watersheds. RSR (RMSE-observations standard deviation ratio) and NSE (Nash-Sutcliffe efficiency) were used to evaluate model performance, consequently M6 for gauged basins (Avg. RSR was 0.76, Avg. NSE was 0.39) and M7 for ungauged basins (Avg. RSR was 0.82, Avg. NSE was 0.31) were selected. Furthermore it was observed that initial loss ratios ranging from 0.01 to 0.10 were more adequate than the fixed ${\lambda}=0.20$ in most of basins.

NRCS-CN 방법을 이용해서 유출량을 결정하는 과정에 가장 큰 영향을 주는 변수는 유출곡선지수와 초기손실률이다. 수자원 실무에서 유출곡선지수와 초기손실률은 대부분 미국 National Engineering Handbook의 지침에 따라 결정하지만, 우리나라 유역의 토양 및 수문학적 특성은 미국과 다르기 때문에 유출량을 과대 또는 과소 산정하게 된다. 따라서 본 연구에서는 우리나라 유역특성에 적합한 유효우량을 산정하기 위하여 점근유출곡선지수법을 이용하여 총 8개의 유효우량 산정 모형(M1~M8)을 제시하였다. RSR (RMSE-observations standard deviation ratio)과 NSE(Nash-Sutcliffe Efficiency)의 두 가지 지표를 이용하여 모형을 평가하였으며, 그 결과 계측 유역에서는 M6 (평균 RSR: 0.76, 평균 NSE: 0.39), 미계측 유역에서는 M7 (평균 RSR: 0.82, 평균 NSE: 0.31)이 최적의 모형으로 선정되었다. 또한 대부분의 유역에서 기존에 사용되고 있던 초기손실률 0.20보다 더 작은 값(0.01-0.10)을 적용할 때 더 좋은 결과를 나타내는 것을 확인하였다.

Keywords

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