Impact analysis of cross-river structures on longitudinal water quality distribution: A case study of agricultural weirs in Osucheon and Yocheon,  Seomjin River basin

Jinyong Eom; Dongho Choi; Daehoon Kim; Jaeyoung Lee; Jina Beom; Yonguk Ryu; Jaewoon Jung

doi:10.3741/JKWRA.2025.58.S-2.1229

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2025 Vol.58, Issue 11S-2 Preview Page Next Page

Research Article

Impact analysis of cross-river structures on longitudinal water quality distribution: A case study of agricultural weirs in Osucheon and Yocheon, Seomjin River basin 하천 횡단구조물이 종방향 수질 분포에 미치는 영향 분석: 섬진강수계 오수천과 요천 농업용 보를 중심으로

30 November 2025. pp. 1229-1237

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Abstract

This study quantitatively evaluated the effects of ten small agricultural weirs—five each in the Osucheon and Yocheon tributaries of the Seomjin River—on stream water quality. Monthly monitoring was conducted from May to October 2019 at points immediately upstream and downstream of each weir for seven parameters, including BOD, TOC, T-N, T-P, and chlorophyll-a (Chl-a). Nonparametric testing (Mann–Whitney U) detected no statistically significant differences in any parameter between upstream and downstream locations in either stream (p > 0.05). Time series analysis supported this result: both locations showed similar seasonal patterns (e.g., dilution during the rainy season), with the exception of Chl-a, which peaked in summer. These findings contrast with the pronounced effects often reported for large, multipurpose weirs. The minimal longitudinal effects observed here are attributed to sampling that was confined to the main channel’s flowing sections, where throughflow is maintained. In weir-affected reaches, however, lateral stagnant zones with reduced velocities frequently co-occur. Therefore, a comprehensive assessment will require high-resolution spatial monitoring that explicitly delineates flowing sections versus lateral stagnant zones to characterize the spatial heterogeneity of water quality.

Keywords

Agricultural weirs

Water quality

Seomjin River basin

Mann-Whitney test

Hydraulic structures

본 연구는 섬진강수계 오수천과 요천에 설치된 10개 농업용 보(하천별 5개소)가 하천 수질에 미치는 영향을 정량적으로 분석하였다. 2019년 5월부터 10월까지 월 1회 보 직상·하류 지점에서 BOD, TOC, T-N, T-P, Chl-a 등 7개 수질 항목을 모니터링하였다. 비모수 통계분석(Mann-Whitney U test) 결과, 두 하천 모두에서 보 상·하류 간 모든 수질 항목 농도가 통계적으로 유의한 차이를 보이지 않았다(p>0.05). 시계열 분석에서도, Chl-a(여름철 증가)를 제외한 대부분 항목이 강우기 희석 효과 등 전형적인 계절 변동을 보였으며, 이러한 경향은 상·하류에서 동일하게 관찰되었다. 이는 대규모 다기능 보의 영향과는 뚜렷이 대조된다. 본 연구에서 농업용 보의 종방향 영향이 미미하게 나타난 것은, 수질 시료 채취가 주흐름이 유지되는 ‘종방향 유수구간(flowing sections)’에 한정되었기 때문으로 판단된다. 실제 보 영향구간 내에는 유속이 느린 ‘횡방향 정체구역(lateral stagnant zones)’이 공존하므로, 향후 보의 영향을 종합적으로 규명하기 위해서는 이들 구간을 명확히 구분하여 수질 공간분포를 파악하는 공간적 정밀 모니터링 연구가 필요하다.

키워드

농업용 보

수질

섬진강수계

Mann-Whitney 검정

수리구조물

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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 : 58
No :11
Pages :1229-1237
Received Date : 2025-09-17
Revised Date : 2025-10-14
Accepted Date : 2025-10-15
DOI :https://doi.org/10.3741/JKWRA.2025.58.S-2.1229

Journal of Korea Water Resources Association ISSN:2799-8746(Print) 2799-8754(Online) 한국수자원학회 논문집

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