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Forecasting of flood travel time depending on weir discharge condition using two-dimensional numerical model in the channel

2차원 수치모형을 이용한 보 방류조건에 따른 하도 내 홍수도달시간 예측

  • Lee, Hae-Kwang (Department of Civil Engineering, Daejin University) ;
  • Oh, Ji-Hwan (Department of Water Resources Research Center, K-water Institute) ;
  • Jang, Suk-Hwan (Department of Civil Engineering, Daejin University) ;
  • Song, Man-Kyu (Department of Civil & Environmental Engineering, Daejin University)
  • 이해광 (대진대학교 토목공학과) ;
  • 오지환 (K-water 연구원 물순환연구소) ;
  • 장석환 (대진대학교 건설시스템공학과) ;
  • 송만규 (대진대학교 토목환경공학과)
  • Received : 2019.03.27
  • Accepted : 2019.04.25
  • Published : 2019.06.30

Abstract

Gate operation of hydraulic structures is important for proper management in rivers. In this study, the characteristics of flood time were analyzed and predicted using the HEC-RAS model, which is capable of one-dimensional and two-dimensional connectivity analysis of the main points downstream of the Geum river. As a result, flood travel time was decreased once discharge increase and downstream water level rising. However, When the floodplain was overflowed, the arrival time increased due to the rapid increase of the river width. Also, the same condition, flood wave travel time at the major point was approximately twice as fast as water level rising travel time, indicating that waves progressed faster than actually water. Using the results of this study, it will be helpful in the river.

우리나라는 지형적인 특성과 강우 발생 특성에 따라 댐이나 다기능보 등 수리구조물의 수문 운영이 하천의 적절한 관리를 위해 매우 중요하다. 이에 본 연구에서는 홍수도달시간에 대한 이론을 정립하고, 금강하류부의 금강하굿둑~백제보 구간을 대상으로 1차원과 2차원의 연계해석이 가능한 HEC-RAS 모형을 활용하여 홍수도달시간을 홍수파도달시간과 수위상승도달시간으로 구분하고 보의 방류조건에 따라 홍수도달시간을 분석 예측하고자 한다. 분석 결과, 방류량이 증가하는 시점에 하도를 범람하여 하천 폭의 급격한 증가로 인해 도달시간이 증가하는 형태가 나타났으며, 홍수파 도달시간이 수위상승 도달시간보다 약 2배정도 빠르게 나타나 실제 도달하는 유수의 양보다 수파가 빨리 진행됨을 알 수 있었다. 본 연구결과를 활용한다면, 하천 관리에 도움이 될 것으로 판단된다.

Keywords

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Fig. 2. Section shape of main point

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Fig. 1. Study area

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Fig. 3. Define of flood travel time

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Fig. 4. Flow of steady state (Oh, 2018)

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Fig. 5. Trend of flood travel time by 2D model in natural river channel (Richards et al., 2012)

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Fig. 6. Generation of terrain and grid

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Fig. 7. Flood water level calibration result of main point (Jul 2017)

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Fig. 8. Flood water level calibration result of main point (Aug 2018)

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Fig. 9. Construction of discharge condition

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Fig. 10. Flood wave travel time by discharge and water level in Gyuam watermark

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Fig. 11. Flood wave travel time by discharge and water level in Ganggyeong watermark

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Fig. 12. Flood wave travel time by discharge and water level in Geum barrage

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Fig. 13. Water level rising travel time by discharge and water level in Gyuam watermark

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Fig. 14. Water level rising travel time by discharge and water level in Ganggyeong watermark

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Fig. 15. Water level rising travel time by discharge and water level in Geum barrage

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Fig. 16. Flood travel time of main point by Beakje weir discharge

Table 1. Flood water level calibration result of study section

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Table 2. Calibration and verification result by 2D numerical model

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Table 3. Flood wave travel time of main station

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Table 4. Water level rising travel time of main station

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