Journal of Korean Society of Disaster and Security (한국방재안전학회논문집)

Korean Society of Disaster & Security (한국방재안전학회)
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Numerical Simulation of Salinity Intrusion into Groundwater Near Estuary Barrage with Using OpenGeoSys

OpenGeoSys를 이용한 하굿둑 인근 지하수 내 염분 침투 수치모의

  • Hyun Jung Lee (Department of Civil and Environmental Engineering, Hongik University) ;
  • Seung Oh Lee (Department of Civil and Environmental Engineering, Hongik University) ;
  • Seung Jin Maeng (Department of Agricultural and Rural Engineering, Chungbuk National University)
  • 이현중 (홍익대학교 건설환경공학과) ;
  • 이승오 (홍익대학교 건설환경공학과) ;
  • 맹승진 (충북대학교 지역건설공학과)
  • Received : 2023.12.06
  • Accepted : 2023.12.27
  • Published : 2023.12.31
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Abstract

The estuary dam is a structure installed and operated in a closed state except when flood event occurs to prevent inland saltwater intrusion and secure freshwater supply. However, the closed state of dam leads to issues such as eutrophication, so it is necessary to examine the extent of saltwater intrusion resulting from the opening of sluice gates. Groundwater, due to its subsurface conditions and slow flow characteristics, is widely analyzed using numerical models. OpenGeoSys, an open-source software capable of simulating Thermal- Hydraulic- Mechanical- Chemical phenomena, was adopted for this study. Simulations were conducted assuming natural flow conditions without dam and operating considering busy farming season, mostly from March to September. Verification of the model through analytical solutions showed error of 3.7%, confirming that OpenGeoSys is capable of simulating saltwater intrusion for these cases. From results simulated for 10 years, considering for the busy farming season, resulted in about 46% reduction in saltwater intrusion length compared to natural flow conditions, approximately 74.36 m. It may be helpful to make choices to use groundwater as a water resource.

하굿둑은 내륙의 염분 침투를 방지하고 공급 용수를 확보하기 위해 설치되어 홍수기를 제외하고 닫힌 상태로 운용되고 있다. 그러나, 수문은 부영양화와 같은 수질 문제를 발생시켜 수질 개선과 용수 공급의 목적을 이루기 위해 수문 운영에 따른 염분 침투영향 파악이 필수적이다. 지하수는 지표하 조건과 느린 흐름 특성으로 인해 수치 모형을 통한 분석이 주로 수행된다. 본 연구에 이용된 OpenGeosys는 열-수리-역학-화학 현상을 모의할 수 있는 오픈소스 모형이다. 모의는 하굿둑이 없는 자연흐름 조건, 3~9월의 농번기를 고려하여 수문이 운영된 조건을 반영하여 수행되었다. 모형은 해석해와 검증하여 3.7%의 오차를 획득함으로써 염분 침투 가능성을 평가하였고, 모의 결과, 농번기를 고려한 수문 운영 조건의 염분침투 길이는 자연흐름 조건보다 46% 감소하여 약 74.36 m로 파악되었다. 본 모의의 결과는 지하수 관련 정책 수립 및 지하수 이용자의 지하수 이용 결정에 기여할 수 있을 것으로 기대된다.

Keywords

Acknowledgement

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 2021R1A2C2013158).

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