Application of an ensemble watershed model for simulation of suspended sediment generation and transport under extreme rainfall events

Taehwan Lee; Hong-Lae Cho; Euisang Jeong

doi:10.3741/JKWRA.2025.58.12.1463

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2025 Vol.58, Issue 12 Preview Page Next Page

Research Article

Application of an ensemble watershed model for simulation of suspended sediment generation and transport under extreme rainfall events 이상강우에 의한 부유사 발생 및 유출 모의를 위한 앙상블 유역모델의 적용

31 December 2025. pp. 1463-1473

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Abstract

In recent years, the frequency and intensity of extreme rainfall events have increased due to climate change, leading to recurring occurrences of turbid water in the Soyang Lake watershed. This study aimed to improve the prediction accuracy of suspended sediment (SS) generation and transport during extreme rainfall events by developing an ensemble watershed model based on the physically based STREAM model, and by evaluating its predictive performance and uncertainty reduction compared with a single model. The ensemble model was constructed by combining different physical formulations for evapotranspiration, soil water retention and hydraulic conductivity, infiltration, and sediment transport processes, resulting in 72 ensemble watershed models (18 hydrologic models × 4 sediment models). Simulations were performed for the upper Soyang Lake watershed using an hourly time step for the 2017-2024 period. As a result, the ensemble mean discharge showed improved performance, with PBIAS decreasing from 45.5% to 38.8% compared to the base single STREAM model. For SS concentration, the ensemble median achieved an R² of 0.26, RMSE of 146.4 mg/L, and PBIAS of 6.9%, which markedly outperformed the single model (R²=0.17, RMSE=209.0 mg/L, PBIAS=-87.2%). These results indicate that the ensemble approach can enhance predictive reliability and stability while reducing the time and uncertainty associated with complex parameter calibration in traditional physically based models. Therefore, the proposed ensemble watershed modeling framework can serve as an efficient alternative for turbidity prediction under extreme rainfall conditions, and its integration with data-driven techniques is expected to further advance the accuracy of ensemble-based predictions.

Keywords

Ensemble watershed model

STREAM

Suspended sediment

Turbidity

Physically based model

Extreme rainfall

최근 기후변화로 인한 이상강우의 빈도와 강도가 증가함에 따라, 소양호에서는 매년 탁수 현상이 반복적으로 발생하고 있다. 본 연구는 이상강우 발생시 부유물질(Suspended sediment, SS)의 발생과 유출을 보다 정확히 예측하기 위해 물리기반 유역모델 STREAM을 기반으로 한 앙상블 유역모델을 구축하고, 단일 모델 대비 예측 성능과 불확실성 저감 효과를 평가하였다. 증발산, 토양수분함량 및 수리전도도, 침투, 유사이동 과정을 서로 다른 물리식으로 조합하여 총 72개의 앙상블 유역모델(18개 수문모델 × 4개 유사모델)을 구성하였으며, 북한강 상류 소양호 유역을 대상으로 2017-2024년 기간 동안 1시간 간격으로 모의를 수행하였다. 그 결과, 기준 STREAM 단일모델에 비해 앙상블 모델의 평균값 적용 시 유량은 PBIAS가 45.5%에서 38.8%로 개선되는 모습을 보였으며, SS 농도의 경우 72개 모델의 중앙값 적용 시 R²=0.26, RMSE=146.4 mg/L, PBIAS= 6.9%로 단일모델(R²=0.17, RMSE=209.0 mg/L, PBIAS=-87.2%) 대비 크게 향상되었다. 이는 앙상블 접근법이 복잡한 매개변수 보정 과정에 소요되는 시간과 불확실성을 줄이면서도, 단일 물리기반 모델 이상의 예측 신뢰도와 안정성을 확보할 수 있음을 보여준다. 따라서 제안된 앙상블 유역모델은 이상강우 발생시 탁수 예측의 효율적 대안으로 활용될 수 있으며, 향후 데이터 기반 기법과의 결합을 통해 더욱 고도화된 예측체계 구축이 가능할 것으로 기대된다.

키워드

앙상블유역모델

STREAM

부유사

탁수

물리기반모델

이상강우

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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 :12
Pages :1463-1473
Received Date : 2025-11-12
Revised Date : 2025-12-03
Accepted Date : 2025-12-03
DOI :https://doi.org/10.3741/JKWRA.2025.58.12.1463

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

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