Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Numerical simulation of flood water level in a small mountain stream considering cross-section blocking and riverbed changes - A case study of Shingwangcheon stream in Pohang before and after Typhoon Hinnamnor flood

단면 폐색과 하상 변화를 고려한 산지 중소하천의 홍수위 수치모의 - 태풍 힌남노 전후의 포항 신광천을 사례로 -

  • Lee, Chanjoo (Deepartment of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Jang, Eun-kyung (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Ahn, Sunggi (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Kang, Woochul (Deepartment of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology)
  • 이찬주 (한국건설기술연구원 수자원하천연구본부) ;
  • 장은경 (한국건설기술연구원 수자원하천연구본부) ;
  • 안성기 (한국건설기술연구원 수자원하천연구본부) ;
  • 강우철 (한국건설기술연구원 수자원하천연구본부)
  • Received : 2023.09.27
  • Accepted : 2023.10.24
  • Published : 2023.12.31
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Abstract

Small and medium-sized mountain rivers that flow through steep, confined valleys carry large amounts of coarse-grained sediment and woody debris during floods. It causes an increase in flood water level by aggrading the riverbed and the cross-section blockage due to driftwood accumulation during flooding. However, the existing flood level calculation in the river basic plan does not consider these changes. In this study, using the Typhoon Hinnamnor flood in September 2022 as an example, we performed numerical simulations using the HEC-RAS model, taking into account the blockage of a cross-section at the bridge and changes in riverbed elevation that occurred during floods, and analyzed the flood level to predict flood risk. This study's results show that flooding occurs if more than 30% of the cross-section is blocked. The rise of flood water levels corresponds to that of the riverbed due to sediment deposition. These results can be used as basic data to prevent and effectively manage flood damage and contribute to establishing flood defense measures that consider actual phenomena.

경사가 급하고 구속된 골짜기를 관류하는 산지 중소하천은 홍수시 다량의 조립질 토사와 유목이 운반된다. 이로 인해 하상의 상승과 유목 집적으로 인한 교량의 폐색이 발생하며 홍수위가 상승한다. 하지만 기존 하천기본계획에서의 홍수위 계산 방식은 홍수시 발생하는 교량 폐색 혹은 하상 변화로 인한 홍수위 변화를 고려하는데 한계가 있다. 본 연구에서는 2022년 9월 태풍 힌남노 홍수를 사례로 홍수시 발생할 수 있는 교량 단면의 폐색과 하도에서의 하상고 변화를 고려하기 위해 HEC-RAS 모형을 이용하여 수치 모의를 수행하고 홍수위를 분석하였다. 연구의 결과 단면이 30% 이상 폐색될 경우 홍수 범람이 발생하며, 하상은 퇴적 높이만큼 홍수위가 상승하는 것으로 나타났다. 이러한 결과는 홍수 피해를 예방하고 효과적으로 관리하기 위한 기초 자료로 활용될 수 있고 실제 현상을 고려한 홍수 방어 대책 수립에 기여할 수 있을 것으로 생각된다.

Keywords

Acknowledgement

이 논문은 한국건설기술연구원 주요사업(기후변화에 대응한 자연기반 하천식생 관리를 위한 생태수문지형 모델 고도화(20230389))의 연구비 지원으로 수행되었습니다.

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