Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Modeling 2D residence time distributions of pollutants in natural rivers using RAMS+

RAMS+를 이용한 하천에서 오염물질의 2차원 체류시간 분포 모델링

  • Kim, Jun Song (Korea Research Institute for Human Settlements) ;
  • Seo, Il Won (Department of Civil and Environmental Engineering, Seoul National University) ;
  • Shin, Jaehyun (Korea Institute of Civil Engineering and Building Technology) ;
  • Jung, Sung Hyun (Department of Civil and Environmental Engineering, Seoul National University) ;
  • Yun, Se Hun (Department of Civil and Environmental Engineering, Seoul National University)
  • 김준성 (국토연구원) ;
  • 서일원 (서울대학교 건설환경공학부) ;
  • 신재현 (한국건설기술연구원) ;
  • 정성현 (서울대학교 건설환경공학부) ;
  • 윤세훈 (서울대학교 건설환경공학부)
  • Received : 2021.02.08
  • Accepted : 2021.05.24
  • Published : 2021.07.31
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Abstract

With the recent industrial development, accidental pollution in riverine environments has frequently occurred. It is thus necessary to simulate pollutant transport and dispersion using water quality models for predicting pollutant residence times. In this study, we conducted a field experiment in a meandering reach of the Sum River, South Korea, to validate the field applicability and prediction accuracy of RAMS+ (River Analysis and Modeling System+), which is a two-dimensional (2D) stream flow/water quality analysis program. As a result of the simulation, the flow analysis model HDM-2Di and the water quality analysis model CTM-2D-TX accurately simulated the 2D flow characteristics, and transport and mixing behaviors of the pollutant tracer, respectively. In particular, CTM-2D-TX adequately reproduced the elongation of the pollutant cloud, caused by the storage effect associated with local low-velocity zones. Furthermore, the transport model effectively simulated the secondary flow-driven lateral mixing at the meander bend via 2D dispersion coefficients. We calculated the residence time for the critical concentration, and it was elucidated that the calculated residence times are spatially heterogeneous, even in the channel-width direction. The findings of this study suggest that the 2D water quality model could be the accidental pollution analysis tool more efficient and accurate than one-dimensional models, which cannot produce the 2D information such as the 2D residence time distribution.

최근 도시와 산업의 발달과 함께 하천, 호소 등 수환경에서의 수질 오염사고가 빈번하게 일어나고 있어 어류폐사, 취수중단, 친수활동 저해 등 심각한 수생태계 및 사회경제적 피해가 발생하고 있다. 따라서 이에 대한 대응책으로 수질모델링을 통한 오염물질의 이동 및 확산에 대한 사전 예측이 필요하다. 본 연구에서는 2차원 하천흐름/수질해석 프로그램인 RAMS+의 현장 적용성 및 예측 정확도를 검증하기 위해 만곡하천인 섬강에서 현장실험을 수행하였다. 모의결과 흐름해석모형 HDM-2Di와 수질해석모형 CTM-2D-TX는 현장실험에서 관측된 2차원 흐름 특성과 오염물질의 거동 및 혼합 양상을 정확하게 재현하였다. 특히 하천의 양안과 만곡부에서 국부적으로 발생하는 저유속 흐름에 의해 오염물질의 거동이 지체되는 저장대 효과를 정확하게 모의하였다. 나아가서 하천 만곡부에서 이차류가 야기하는 오염물질 3차원적 혼합 양상을 2차원 분산계수를 통해 효과적으로 재현하였다. 오염물질의 위험농도 체류시간은 취수중단 기간을 결정하는데 있어 매우 중요한 요소이다. 본 연구에서는 CTM-2D-TX 모의결과를 기반으로 오염물질 위험농도 체류시간을 계산하였고, 위험농도 체류시간의 공간적 분포가 하폭방향으로 큰 편차를 지니고 있음을 확인하였다. 이러한 오염물질의 2차원적 체류 특성은 1차원 수질모형을 통해서는 예측이 불가능하기 때문에 효율적이고 정확한 수질사고대응을 위해 2차원 수질모형의 활용이 필요함을 본 연구의 결과는 시사하고 있다.

Keywords

Acknowledgement

본 연구는 환경부 화학사고 대응 환경기술개발사업(2018001960001)의 연구비 지원에 의하여 수행되었습니다. 본 연구는 서울대학교 공학연구원과 건설환경종합연구소의 지원으로 이루어졌습니다. 서울대, 창원대, 인제대, 단국대 그리고 미국지질조사국(USGS) 연구팀의 현장실험 지원에 감사드립니다.

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