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2026 Vol.31, Issue 5 Preview Page

Research Paper

Comparison of SWAT-Derived Delayed-Flow and Eckhardt-Filtered Baseflow Indices in the Hwangjeoncheon Watershed

황전천 유역에서 SWAT 기반 지연유출지수와 Eckhardt 디지털 필터 기반 기저유출지수의 비교 분석

Jin Chul Joo1*
,
Kangwei Shi2
,
Seonggyu Park3
,
Kyung In Chae4
,
Su Ryeon Kim5
,
Yong-Ho Choi6
,
Kwang-Wook Jeong6
,
In-Kyun Jeong6
주 진철1*
,
쉬캉웨이2
,
박 성규3
,
채 경인4
,
김 수련5
,
최 용호6
,
정 광욱6
,
정 인균6
1Department of Civil and Environmental Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
2Department of Environmental Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
3Texas Tech University, Department of Civil, Environmental & Construction Engineering, Lubbock, TX 79409−1023, USA
4Water supply & Wastewater Research Center, K-water Research Institute, Korea Water Resources Corporation, Daejeon 34045, Republic of Korea
5GeoGreen21 Co., Ltd., Seoul 08376, Republic of Korea
6Water & Environment Co., Ltd., Namyangju 12248, Republic of Korea
1국립한밭대학교 건설환경공학과
2국립한밭대학교 환경공학과
3Texas Tech University, Department of Civil, Environmental & Construction Engineering
4한국수자원공사 K-water 연구원 상하수도연구소
5㈜지오그린21
6㈜물과환경
*Corresponding Author
31 October 2026. pp. 112-130
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Abstract

This study evaluated the spatiotemporal variability and hydrological implications of the baseflow index (BFI) and delayed-flow index (DFI) in the Hwangjeoncheon watershed, a tributary of the Seomjin River basin, using SWAT-simulated runoff components and streamflow-based baseflow separation methods. The SWAT model was established with a warm-up period (2007–2011), calibration period (2012–2018), and validation period (2019–2024). Model performance evaluated using monthly streamflow showed R2, NSE, and PBIAS values of 0.760, 0.737, and 0.66% during calibration and 0.857, 0.851, and -1.45% during validation, respectively, indicating satisfactory streamflow simulation. During 2019–2023, surface runoff, interflow, and baseflow accounted for 43%, 30%, and 27% of cumulative runoff, respectively. Accordingly, the SWAT-derived BFI (BFISWAT) was 0.27, while the DFI (DFISWAT), incorporating interflow and baseflow, was approximately 0.57. The arithmetic mean of annual DFISWAT values was 0.61. Surface runoff dominated during summer, whereas delayed-flow contributions increased during autumn, winter, and non-irrigation periods. Under the selected parameter settings, the Eckhardt BFI (0.57) was closer to the mean annual DFISWAT (0.61) than to BFISWAT (0.27), whereas LH2P, PART, and EWMA produced values relatively closer to BFISWAT. These findings suggest that empirical baseflow estimates depend on separation methods and parameter settings, and that Eckhardt-filtered baseflow may partly reflect slowly receding components, including interflow. DFISWAT generally decreased with increasing precipitation, while the highest spatial baseflow contribution occurred in the midstream reach (approximately 39%). Overall, distinguishing SWAT-derived BFI and DFI provides a complementary framework for interpreting empirical baseflow estimates. However, uncertainties in model-based runoff partitioning and filter parameters highlight the need for independent hydrological validation.

Keywords
Baseflow index
Baseflow separation
Delayed-flow index
Eckhardt digital filter
Hwangjeoncheon watershed
SWAT
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Information
  • Publisher :The Korean Society of Soil and Groundwater Environment
  • Publisher(Ko) :한국지하수토양환경학회
  • Journal Title :Journal of Soil and Groundwater Environment
  • Journal Title(Ko) :지하수토양환경
  • Volume : 31
  • No :5
  • Pages :112-130
  • Received Date : 2026-09-11
  • Revised Date : 2026-10-27
  • Accepted Date : 2026-10-29
  • DOI :https://doi.org/10.7857/JSGE.2026.31.5.112
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