Journal of Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회논문집)

Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회)
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Development of a Numerical Model to Analyze the Formation and Development Process of River Mouth Bars

하구사주의 생성 및 발달을 해석하기 위한 수치모델의 개발

  • Kim, Yeon-Joong (Department of Civil and Urban Engineering, Inje University) ;
  • Woo, Joung-Woon (Department of Civil and Urban Engineering, Inje University) ;
  • Yoon, Jong-Sung (Department of Civil and Urban Engineering, Inje University) ;
  • Kim, Myoung-Kyu (Research Center, Hydro Technology Institute Korea)
  • 김연중 (인제대학교 토목도시공학부) ;
  • 우정운 (인제대학교 토목도시공학부) ;
  • 윤종성 (인제대학교 토목도시공학부) ;
  • 김명규 (HTI코리아, R&D센터)
  • Received : 2021.11.15
  • Accepted : 2021.12.20
  • Published : 2021.12.31
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Abstract

An integrated sediment management approach that includes the recovery of the amount of declined sediment supply is effective as a fundamental solution to coastal erosion. During planning, it is essential to analyze the transfer mechanism of the sediments generated from estuaries (the junction between a river and sea) to assess the amount and rate of sediment discharge (from the river to sea) supplied back to the coast. Although numerical models that interpret the tidal sand bar flushing process during flooding have been studied, thus far, there has been no study focusing on the formation and development processes of tidal sand bars. Therefore, this study aims to construct wave deformation, flow regime calculation, and topographic change analysis models to assess the amount of recovered sediment discharge and reproduce the tidal sand bar formation process through numerical analysis for integrated littoral drift management. The tidal sand bar formation process was simulated, and the wave energy and duration of action concepts were implemented to predict the long-term littoral movement. The river flux and wave conditions during winter when tidal sand bars dominantly develop were considered as the external force conditions required for calculation. The initial condition of the topographic data directly after the Maeupcheon tidal sand bar flushing during flooding was set as the initial topography. Consequently, the tidal sand bar formation and development due to nearshore currents dependent on the incident wave direction were reproduced. Approximately 66 h after the initial topography, a sand bar formation was observed at the Maengbang estuary.

해안침식의 근본적 대책으로서 감소한 공급 토사량 회복을 포함한 종합 토사관리 대책이 유효하지만, 계획에 있어서는 하천에서 바다로 유출된 토사 가운데 어느 정도의 양이 어느 정도의 속도로 해안에 다시 공급되는 토사량의 평가와 이를 위해서는 하천과 바다의 결절점인 하구지역에서 발생하는 토사의 이동 메커니즘 분석이 매우 중요하다. 하지만 지금까지 홍수 시의 하구사주 붕괴(flushing) 과정을 해석하는 수치모델에 관한 연구는 진행되고 있지만 하구사주의 형성 및 발달 과정을 해석하는 수치모델은 아직 확립되어 있지 않은 것이 현재의 연구 진행상태이다. 본 연구에서는 종합토사관리를 위해 유출된 토사가 회복되는 토사량의 평가를 위해 파랑변형, 유황계산 및 지형변화 모델을 구축하여 하구사주의 생성과정을 수치해석을 통한 재현을 목적으로 한다. 하구사주의 생성과정을 모의하였으며 에너지 파랑 및 작용 시간의 개념을 도입하여 장기간 표사이동의 예측을 실시하였다. 계산에 필요한 외력조건은 하구사주가 지배적으로 발달하는 동계시 작용하는 파랑조건과 하천의 유량을 고려하였으며 초기지형은 홍수시 마읍천의 하구사주가 붕괴(flushing)된 직후의 지형정보를 초기조건으로 설정하였다. 그 결과 입사파향에 따라 해빈류에 의해 하구사주의 발달과 생성과정을 재현하였으며 초기지형으로부터 약 66시간 경과 후 맹방하구 사주의 형태로 발달되는 것으로 나타났다.

Keywords

Acknowledgement

본 연구는 2018년 해양수산부(과제번호 20180404) 재원으로 해양수산과학기술진흥원의 지원을 받아 수행된 연구결과 중 일부임음 밝히며, 연구비 지원에 감사드립니다.

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