Reliability analysis of measured flow in mountainous stream segments using physically-based distributed modeling

Jun Lee; Tae-Hyeong Kim; Jiyoung Sung; Boosik Kang

doi:10.3741/JKWRA.2024.57.11.883

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2024 Vol.57, Issue 11 Preview Page Next Page

Research Article

Reliability analysis of measured flow in mountainous stream segments using physically-based distributed modeling 물리기반 분포형모델을 사용한 산지하천구간에서의 계측유량 신뢰도 평가

30 November 2024. pp. 883-896

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Abstract

Gauging data from seven rainfall events in the upstream Sancheong sub-basin of the Namgang Dam watershed were collected to evaluate the measurement reliability at the Sancheong, Imcheon, Hamyang, and Anui stations based on runoff ratio and specific peak discharge. The measurement reliability matrix for each event and station showed that 6(31.6%) were classified as “severe” level, 9 (47.4%) as “caution” level, and 3(15.8%) as “moderate” level, indicating that 79.0% of the 19 measurement values were at caution level or higher. Although this study was based on a sample of seven rainfall events, it highlights the need for a thorough evaluation of streamflow measurements in mountainous streams in Korea. The reliability of a physically-based distributed rainfall-runoff model (Vflo) applied to mountain stream segments was also assessed using the same data. The results showed that the observed values at the Sancheong station, located at the sub-basin outlet, had a relatively high R² value of 0.93 compared to the upstream Imcheon, Hamyang, and Anui stations, where missing or anomalous data led to a lower R² of 0.67. In many cases, the upstream flow was either over- or underestimated, and when simulated with these values as boundary conditions, total runoff errors reached up to 12%, and peak discharge errors up to 40%. The analysis of runoff ratios across various rainfall events was used to evaluate the data reliability at upstream observation points, which could serve as a basis for correcting the observed values at each gauging station.

Keywords

Distributed modeling

Vflo

Gauged flowrate assessment

Mountenous stream

Reliability of gauged streamflow

남강댐 유역 상류 산청 소유역을 대상으로 7개의 강우사상에 대한 관측자료를 수집하여 유출률과 첨두비유량을 이용하여 산청, 임천, 함양, 안의지점의 계측신뢰도를 평가하였다. 강우사상별 지점별 계측신뢰도 매트릭스를 산정한 결과 6개(31.6%)가 심각수준, 9개(47.4%)가 주의수준, 3개(15.8%)가 관심수준으로 나타나, 전체 19개 계측값의 79.0%가 주의수준이상의 신뢰도를 보이고 있었다. 본 연구는 7개 강우사상에 대한 표본을 대상으로한 평가였지만 국내 산지하천의 유량계측에 대한 면밀한 평가가 필요함을 시사할 수 있는 결과이다. 또한 동일한 자료를 이용해 구축한 산지 계곡류하천구간에서 물리기반 분포형 강우-유출모델링(Vflo)의 신뢰도를 평가하였다. 분석 결과, 소유역출구인 산청지점의 관측값은 계곡류의 특성이 강하게 나타나는 상류의 임천, 함양, 안의 소유역에 비해 상대적으로 0.93의 결정계수(R²)값으로 높은 신뢰도를 보였으며, 상류 소유역의 관측값은 결측치나 이상치가 많아 0.67의 낮은 신뢰도를 보였다. 특히, 상류에서 유출량이 과대 또는 과소하게 관측된 경우가 많았으며, 이를 경계 조건으로 설정하여 모의한 결과, 총 유출량 오차는 최대 12%, 첨두 유량 오차는 최대 40%까지 발생하였다. 다양한 강우 사상에 대한 유출률을 분석하여 상류 관측 지점의 자료 신뢰도를 평가하였으며, 이는 각 관측소의 관측값 보정에 대한 근거가 될 수 있을 것으로 사료된다.

키워드

분포형 모형

Vflo

계측유량 평가

산지 계곡류

계측유량 신뢰도

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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 : 57
No :11
Pages :883-896
Received Date : 2024-08-16
Revised Date : 2024-10-17
Accepted Date : 2024-10-30
DOI :https://doi.org/10.3741/JKWRA.2024.57.11.883

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

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