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2026 Vol.59, Issue 2 Preview Page

Research Article

Estimation of the vegetation mortality conditions on a riparian sand bar using the field observation and numerical simulation - A case of herbaceous plant in Korea

야외관측 및 수치해석을 이용한 하천 사주 상 식생 사멸조건의 추정 - 초본류 사례

Hyoseop Wooa
,
Chang-Lae Jangbc
,
Chanjoo Leed
,
Hyung-jin Choe
,
Sung-uk Choif*
우 효섭a
,
장 창래bc
,
이 찬주d
,
조 형진e
,
최 성욱f*
aVisiting Professor, Department of Civil and Environmental Engineering, Yonsei University, Seoul, Korea
bProfessor, Department of Civil Engineering, Korea National University of Transportation, Chungju, Korea
cDirector, Research Institute for Climate Change and Nature Disasters, Korea National University of Transportation, Chungju, Korea
dResearch Fellow, Korea Institute of Civil Engineering and Building Technology, Goyang, Korea
eCEO, ECOnGEO inc, Inchon, Korea
fProfessor, Department of Civil and Environmental Engineering, Yonsei University, Seoul, Korea
a연세대학교 건설환경공학과 객원교수
b한국교통대학교 건설환경도시교통공학부 교수
c한국교통대학교 기후변화와 자연재해연구소 소장
d한국건설기술연구원 연구위원
e주식회사 에코앤지오 대표이사
f연세대학교 건설환경공학과 교수
*Corresponding Author
28 February 2026. pp. 147-158
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Abstract

Riparian plants recruited by hydrochory often experience high mortality during their early growth period, primarily due to three factors: 1) insufficient soil moisture, 2) excessive duration of inundation, and 3) physical instability of their habitat caused by flow and sediment transport processes such as excavation, uprooting, and burial. In this study, we investigated the critical mortality conditions associated with physical instability during the recruitment stage of the herbaceous riparian species Persicaria nodosa (node smartweed), a common pioneer plant in Korean sand-bed rivers, using field observations in conjunction with numerical analysis. We monitored germination, seedling establishment, and subsequent growth of the species within a selected reach of a sand-bed river in Korea. To assess the flow conditions under which plants are likely to survive or die, we conducted numerical simulations of the reach to obtain two-dimensional distributions of bed shear stress. A validated hydraulic model was used to reproduce critical flow periods observed during the monitoring years. In the analysis, we assumed that the Shields number (dimensionless shear stress) could serve as an indirect indicator of the physical threshold for plant survival. Our results show that the Shields number associated with physical mortality varies markedly with plant age. For two-month-old seedlings, the threshold lies between 0.19 and 0.24, whereas four-month-old plants require values exceeding 0.37. These findings differ substantially from the common assumption in vegetation-dynamics models that mortality of recruitment-stage plants can be represented using the critical Shields threshold of approximately 0.04-0.06. The results clearly demonstrate that age-dependent resistance must be considered when modelling mortality of pioneer vegetation on riparian sand bars.

Keywords
Flow and sediment regime
Herbaceous plant
Numerical modeling
Recruitment stage
Riparian vegetation mortality
Sand bars
Shields number

하안식생은 수매작용으로 이입, 활착하는 과정에서 보통 1) 토양수분 부족, 2) 장기간 침수, 3) 흐름 및 유사 이동으로 인한 서식지 표면의 물리적 불안정(침식, 뿌리 뽑힘, 매몰) 등 이유로 사멸할 수 있다. 본 연구에서는 국내 모래하천에 흔히 서식하는 초본식물인 명아자여뀌를 대상으로 물리적 불안정성으로 인한 사멸의 한계조건을 특히 식생 이입기에 초점을 맞추어 현장 관찰과 수치 분석을 통해 조사했다. 이를 위해 낙동강 제1지류인 내성천의 한 구간에서 대상 식물의 발아 및 생장 과정을 관찰했다. 다음, 식물이 서식하는 하안사주의 물리적 불안정성으로 인해 식생 이입기에 사멸할 수 있는 흐름 조건을 추정하기 위해 2차원 흐름 수치모의를 수행했다. 본 연구에서 식생과 하상의 물리적 불안정성에 의한 사멸의 간접적 지표로서 Shields 수를 이용하였다. 그 결과 이입기인 2개월 자란 7 cm 높이 명아자여뀌 사멸조건은 Shields 수로 0.19보다 크나 0.24보다 작으며, 4개월 된 50 cm 높이 식생의 경우 0.37보다 큰 것으로 나타났다. 이 결과는 Shields 수 0.04-0.06 를 보통 하안식생의 초기 사멸기준으로 사용하는 현 식생동역학 모델링의 실무 값과 큰 차이를 보여준다. 또한, 하안사주 상 초기식생의 생존과 사멸을 평가하기 위해서는 생장시기 별 한계조건을 고려하여야 한다.

키워드
흐름 및 유사 레짐
초본류
수치모의
식생 이입기
하안식생사멸
모래사주
Shields 수
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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 :2
  • Pages :147-158
  • Received Date : 2025-09-02
  • Revised Date : 2025-12-19
  • Accepted Date : 2025-12-23
  • DOI :https://doi.org/10.3741/JKWRA.2026.59.2.147
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