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2026 Vol.59, Issue 8 Preview Page
Experimental study of wave overtopping reduction and Its associated flow mechanisms induced by trench excavation at the dune toe

사구 전면부 도랑 굴착에 따른 월파 저감과 유동 메커니즘에 대한 실험적 연구

Hyerim Leea
,
Yeulwoo Kimb*
,
Sang-Ho Ohc
이 혜림a
,
김 열우b*
,
오 상호c
aMaster Student, Department of Civil Engineering, Pukyong National University, Busan, Korea
bAssociate Professor, Department of Civil Engineering, Pukyong National University, Busan, Korea
cProfessor, Department of Civil Engineering, School of Smart and Green Engineering, Changwon National University, Changwon, Korea
Professor, Department of Civil Engineering, School of Smart and Green Engineering, Changwon National University, Changwon, Korea
a국립부경대학교 토목공학과 석사과정
b국립부경대학교 토목공학과 부교수
c창원대학교 토목공학과 교수
창원대학교 토목공학과 교수
*Corresponding Author
31 August 2026. pp. 843-857
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Abstract

This study proposes a nature-based solution involving trench excavation in front of a coastal dune and quantitatively evaluated its overtopping reduction performance through laboratory experiments. Experiments were conducted in a two-dimensional wave flume under regular and irregular wave conditions, considering six structural configurations combining two dune geometries and three trench widths. Mean overtopping rates were analyzed as a function of relative freeboard and dimensionless trench width. Evaluation of the EurOtop empirical formula shows that the existing formula does not adequately account for the additional overtopping reduction attributable to trench excavation. To address this limitation, a trench influence factor expressed as an exponential function of dimensionless trench width was proposed, which reduced the normalized root mean square error (NRMSE) from 6.80% to 0.60% for regular waves and from 0.56% to 0.25% for irregular waves, significantly improving prediction accuracy. Bubble image velocimetry analysis further reveals that overtopping reduction occurs through a two-stage mechanism. In the first stage, part of the incoming flow is trapped within the trench, reducing initial overtopping. An additional shear layer forms inside the trench through returning flow-wave interaction, leading to secondary overtopping reduction. These findings demonstrate that trench excavation can serve as an effective overtopping mitigation measure by enhancing flow dispersion and energy dissipation, highlighting its potential as a practical nature-based coastal protection measure.

Keywords
Nature-based solution
Coastal dune
Trench excavation
Wave overtopping
EurOtop
Bubble image velocimetry

본 연구는 사구 전면부에 도랑을 굴착하는 자연기반 공법을 제안하고, 수리모형실험을 통해 그 월파 저감 효과를 정량적으로 평가하였다. 2차원 조파수조에서 두 가지 사구 형상과 세 가지 도랑 폭을 조합하여 여섯 가지 구조물 조건에 대해 규칙파 및 불규칙파 조건에서 실험을 수행하였으며, 상대 여유고 및 무차원 도랑 폭에 따른 평균 월파량을 분석하였다. EurOtop 경험식의 적용성을 검토한 결과, 기존 경험식은 도랑에 의한 추가적인 월파 저감 효과를 충분히 반영하지 못하는 것으로 나타났다. 이를 보완하기 위하여 무차원 도랑 폭을 변수로 하는 지수함수 형태의 영향계수(γt)를 제안하였으며, 영향계수 적용 결과 예측 성능이 크게 향상되었다. 또한 기포 영상 유속계 분석을 통해 도랑 조건에서는 유입 유체의 일부가 도랑 내부로 먼저 유입되면서 초기 월파가 저감되고, 이후 되돌아오는 유체와 후속 파랑의 상호작용 과정에서 도랑 내부에 추가적인 전단층이 형성되어 이차 월파 저감이 발생하는 것으로 나타났다. 이러한 결과는 도랑 굴착이 유동 분산과 에너지 소산을 통해 효과적인 월파 저감 기법으로 활용될 수 있음을 시사한다.

키워드
자연기반 공법
해안 사구
도랑 굴착
월파
EurOtop
기포 영상 유속계
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Information
  • Publisher :KOREA WATER RESOURECES ASSOCIATION
  • Publisher(Ko) :한국수자원학회
  • Journal Title :Journal of Korea Water Resources Association
  • Journal Title(Ko) :한국수자원학회 논문집
  • Volume : 59
  • No :8
  • Pages :843-857
  • Received Date : 2026-05-14
  • Revised Date : 2026-06-08
  • Accepted Date : 2026-06-09
  • DOI :https://doi.org/10.3741/JKWRA.2026.59.8.843
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