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Original Article

A Study on the Quantitative Comparative Assessment of Structural and Functional River Connectivity

하천의 구조적 연결성과 기능적 연결성의 정량적 비교 평가 연구

Hong Il1
,
Hyoung Sub Sin2
,
Joon Gu Kang3
,
Hong Koo Yeo4
,
Dong Ho Nam5*
홍 일1
,
신 형섭2
,
강 준구3
,
여 홍구4
,
남 동호5*
1Senior Researcher, Hydro Science and Hydro Engineering Institute, Korea Institute of Construction Technology, Goyang 10223, Korea
2CEO, Hydro ERI Solution Inc, Goyang 10390, Korea
3Research Fellow, Hydro Science and Hydro Engineering Institute, Korea Institute of Construction Technology, Goyang 10223, Korea
4Senior Research Fellow, Hydro Science and Hydro Engineering Institute, Korea Institute of Construction Technology, Goyang 10223, Korea
5Post-doctoral Researcher, Hydro Science and Hydro Engineering Institute, Korea Institute of Construction Technology, Goyang 10223, Korea
1한국건설기술연구원 수자원하천연구본부 수석연구원
2㈜이알아이솔루션 대표
3한국건설기술연구원 수자원하천연구본부 연구위원
4한국건설기술연구원 수자원하천연구본부 선임연구위원
5한국건설기술연구원 수자원하천연구본부 박사후연구원
*Corresponding Author
31 December 2025. pp. 300-310
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Abstract

This study proposes a new methodology for the quantitative assessment of longitudinal river connectivity. Current assessments in Korea rely on qualitative grades (Continuous, Damaged, Disconnected), which limit quantitative comparison as most rivers are classified as ’Disconnected’ based on the lowermost barrier. Furthermore, while the existing Dendritic Connectivity Index (DCI) reflects network structure, it assumes all barriers cause complete disconnection, thereby failing to capture actual ecological functions. To address these limitations, this study proposes a new functional connectivity index, DCIm, which integrates field-measured “fish passage rates (%)“ from Korean guidelines into the DCI framework. The DCIm index is calculated using the cumulative product of passability rates for all downstream barriers, establishing the theoretical relationship DCIm≤DCI (functional connectivity≤structural connectivity). When applied to three Korean rivers (Gokseongcheon, Samcheok-osipcheon, and Hancheon), the structural DCI was 3.53%~9.80%. However, the actual functional connectivity (DCIm) was significantly lower (0.53%~4.43%), resulting from the presence of barriers with low or zero fish passage rates (i.e., functional disconnection). This study defines the difference between DCI (structural potential) and DCIm (actual function) as the “functional limitation“ caused by barrier inefficiency, providing an analytical framework for its quantification. The proposed index complements the current qualitative assessment by offering a quantitative scale and serves as an evaluation tool to separately analyze the effects of barrier removal versus barrier enhancement (i.e., improving passability). This framework is expected to contribute to more rational priority setting in river restoration and management planning.

Keywords
DCI
DCIm
Longitudinal river connectivity
Passage rates
River crossing structure

본 연구는 하천의 종적 연결성을 정량적으로 평가하기 위한 새로운 방법론을 제시한다. 현행 국내 하천 연속성 평가는 ‘연속’, ‘훼손’, ‘단절’의 정성적 등급을 사용하며, 하류의 횡단구조물 상태에 따라 대부분의 하천이 단절(또는 훼손)로 평가되는 등 정량적 비교에 한계가 있다. 또한 기존 DCI 지표는 하천망의 구조적 특성은 반영하지만, 모든 구조물이 완전한 단절 상태로 가정되어 실제 생태학적 기능을 충분히 반영하지 못한다. 이러한 한계를 보완하기 위해, 본 연구에서는 DCI의 평가 틀에 국내 지침의 실측 자료인 어류 이동률(%)을 통합하여 새로운 기능적 연결성 지표인 DCIm을 제안하였다. DCIm은 하류측 모든 구조물의 통과율을 누적하여 곱하는 방식을 적용함으로써, DCIm≤DCI(기능적 연결성≤ 구조적 연결성)라는 관계가 성립된다. 개발된 지표를 곡성천, 삼척오십천, 한천에 적용한 결과, 횡단구조물 설치로 인한 DCI는 3.53%~9.80% 범위로 나타났다. 그러나 어류 이동률이 낮거나 0%인 구조물(기능적 단절)이 존재함에 따라, 실제 기능적 연결성(DCIm)은 0.53%~4.43% 범위로 DCI보다 더욱 낮게 산정되었다. 본 연구는 DCI(구조적 잠재력)와 DCIm(실제 기능)의 차이를 구조물 기능 저하로 인한 기능적 제약으로 해석하고, 이를 정량적으로 평가하는 분석틀을 제시하였다. 제안된 지표는 현행 등급제 평가의 정량적 한계를 보완하며, 구조물 제거와 구조물 기능 개선의 효과를 분리하여 검토할 수 있는 평가방법으로 활용 가능하다. 이를 통해 하천복원 및 관리계획의 합리적 우선순위 설정에 기여할 수 있을 것으로 판단된다.

키워드
DCI
DCIm
하천 종적 연결성
통과율
횡단구조물
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Information
  • Publisher :Korean Society of Ecology and Infrastructure Engineering
  • Publisher(Ko) :응용생태공학회
  • Journal Title :Ecology and Resilient Infrastructure
  • Journal Title(Ko) :응용생태공학회 논문집
  • Volume : 12
  • No :4
  • Pages :300-310
  • Received Date : 2025-11-17
  • Revised Date : 2025-11-26
  • Accepted Date : 2025-12-01
  • DOI :https://doi.org/10.17820/eri.2025.12.4.300
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