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2026 Vol.59, Issue 2 Preview Page

Research Article

An evaluation of subcatchment delineation methods for enhanced accuracy in urban flood analysis

도시침수 분석 정확성 향상을 위한 소유역 분할 기법 평가

Geumchae Shina
,
Junghwan Leeb*
신 금채a
,
이 정환b*
aResearcher, K-water Research Institute, Korea Water Resources Corporation (K-water), Daejeon, Korea
bSenior Researcher, K-water Research Institute, Korea Water Resources Corporation (K-water), Daejeon, Korea
aK-water연구원 수자원환경연구소 연구원
bK-water연구원 수자원환경연구소 선임연구원
*Corresponding Author
28 February 2026. pp. 201-212
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Abstract

With accelerating climate change and urbanization, urban flooding caused by localized extreme rainfall has become more frequent, increasing the need for accurate numerical modeling of urban drainage systems. This study evaluates the impact of subcatchment delineation methods on urban flood simulations by comparing DEM-based and Thiessen polygon-based approaches. A coupled 1D-2D hydrologic-hydrodynamic model was developed using InfoWorks ICM, and simulations were conducted under identical rainfall, drainage network, and pump operation conditions. Model outputs were quantitatively compared using the coefficient of determination (R2), Nash-Sutcliffe efficiency (NSE), and root mean square error (RMSE), and simulated inundation extents were validated against observed flood trace maps. The results show that subcatchment delineation has a limited effect on overall inundation magnitude at the watershed scale, but significantly influences the reproduction of localized flow dynamics and flood-prone areas. These findings highlight the importance of selecting an appropriate delineation strategy based on the objectives of urban flood analysis and provide useful insights for future flood modeling and urban drainage planning.

Keywords
Urban flooding
Subcatchment
ArcGIS
DEM
Thiessen polygon

기후변화와 도시화의 가속화로 도시침수 발생 빈도가 증가함에 따라, 도시 배수 시스템의 침수 거동을 정확히 재현하기 위한 수치모형 기반 분석의 중요성이 커지고 있다. 본 연구는 도시침수 모의 과정에서 핵심적인 전처리 단계인 소유역 분할 방식에 주목하여, DEM (Digital Elevation Model) 기반 소유역 분할과 Thiessen 다각형 기반 소유역 분할이 도시침수 해석 결과에 미치는 영향을 비교·분석하는 것을 목적으로 하였다. InfoWorks ICM을 활용하여 1D-2D 연계 수리·수문 모형을 구축하였으며, 두 소유역 분할 방식에 대해 동일한 강우 조건과 하수관망 및 펌프 운영 조건을 적용하여 도시 배수 및 침수 모의를 수행하였다. 분할 방식에 따른 결과 차이를 정량적으로 평가하기 위해 결정계수(R2), Nash-Sutcliffe 효율계수(NSE), RMSE를 활용하였고, 모의된 침수 분포는 침수 흔적도와 비교하여 공간적 타당성을 검토하였다. 분석 결과 소유역 분할 방식은 펌프 토출량 규모에는 큰 영향을 미치지 않는 것으로 분석되었다. 반면, 국지적인 유량 변화 및 침수 취약 구간의 세부 재현에는 분할 방식에 따라 차이가 발생하여, 침수 위치와 흐름 특성의 공간적 표현에 영향을 미치는 것으로 확인되었다. 이는 도시침수 해석에서 분석 목적에 따라 소유역 분할 방식을 합리적으로 선택하는 것이 중요함을 시사한다.

키워드
도시침수
소유역 분할
지형모델
Thiessen 다각형
References
1

Autodesk (2025). What’s new in InfoWorks ICM (Version 2025.5). San Rafael, CA, U.S.

2

Cho, W.-H., Han, K.-Y., Kim, H.-S., and Kim, J.-S. (2015). “A study on inundation analysis considering inland and river flood.” Journal of the Korean Association of Geographic Information Studies, Vol. 18, No. 1, pp. 74-89.

10.11108/kagis.2015.18.1.074
3

Dong, Z., Bain, D.J., Akcakaya, M., and Ng, C.A. (2023). “Evaluating the Thiessen polygon approach for efficient parameterization of urban stormwater models.” Environmental Science and Pollution Research, Vol. 30, No. 11, pp. 30295-30307.

10.1007/s11356-022-24162-7
4

EPA Catchments Unit (2019). What happens when we urbanise a catchment? accessed 19 February 2026, <https://www.catchments.ie/what-happens-when-we-urbanise-a-catchment/>.

5

Gwangsan-gu (2022). Feasibility review report for the Gwangsan-gu small stream maintenance master plan. Technical Report.

6

Heo, S.-C., Park, S.-S., and Lee, J.-T. (2008). “Runoff analysis of urban subcatchments considering watershed shape.” Journal of the Korean Water Resources Association, Vol. 41, No. 5, pp. 491-501.

10.3741/JKWRA.2008.41.5.491
7

Jankowfsky, S., Branger, F., Braud, I., Gironás, J., and Rodriguez, F. (2013). “Comparison of catchment and network delineation approaches in complex suburban environments: Application to the Chaudanne catchment, France.” Hydrological Processes, Vol. 27, No. 25, pp. 3747-3761.

10.1002/hyp.9506
8

Ji, S., and Qiuwen, Z. (2015). “A GIS-based subcatchments division approach for SWMM.” The Open Civil Engineering Journal, Vol. 9, pp. 515-521.

10.2174/1874149501509010515
9

Kang, B.-S. (2019). A study on rainfall analysis and estimation method of flood discharge in Jeju urban streams. Ph.D. Dissertation, Jeju National University.

10

Kim, H.-I., Lee, Y.-S., and Kim, B.-H. (2021). “Real-time urban inundation prediction using a random forest regression model.” Journal of Korea Water Resources Association, Vol. 54, No. S-1, pp. 1119-1130.

11

Kim, K.T., and Choi, Y.S. (2003). “A study on runoff response according to dividing watershed.” Journal of the Korean Water Resources Association, Vol. 36, No. 6, pp. 911-924.

10.3741/JKWRA.2003.36.6.911
12

Korea Research Institute for Human Settlements (KRIHS) (2022). Land issues report 2022. KRIHS Policy Brief.

13

Lee, J.H., Yuk, G.M., Moon, H.T., and Moon, Y.I. (2020). “Integrated flood forecasting and warning system against flash rainfall in the smallscaled urban stream.” Atmosphere, Vol. 11, No. 9, 971.

10.3390/atmos11090971
14

Lee, S.-H., Choi, H.-J., Woo, H.-A., Kim, M.-Y., Lee, E.-H., Kim, S.-H., and Noh, S.-J. (2024). “Development and application of a cellular automata-based urban inundation and water cycle analysis model (CAW).” Journal of Korea Water Resources Association, Vol. 57, No. 3, pp. 165-179.

15

Ministry of Environment (ME) (2005). Hongseongcheon river maintenance basic plan. River Information Management System.

16

National Disaster Management Research Institute (NDMI) (2024). Development of a sensor point-linked urban inundation prediction technology. NDMI-PR-2024.

17

Park, J.-H., and Kang, B.-S. (2006). “Comparison of runoff analysis between GIS-based distributed model and lumped model for flood forecast of dam watershed.” Journal of the Korean Association of Geographic Information Studies, Vol. 9, No. 3, pp. 171-182.

18

Park, M.-G. (2018). “Effects of terrain and rainfall grid size on runoff calculation in distributed runoff models.” Journal of the Korean Society of Hazard Mitigation, Vol. 18, No. 7, pp. 173-181.

10.9798/KOSHAM.2018.18.7.173
19

Saksena, S., and Merwade, V. (2015). “Incorporating the effect of DEM resolution and accuracy for improved flood inundation mapping.” Journal of Hydrology, Vol. 530, pp. 180-194.

10.1016/j.jhydrol.2015.09.069
20

Si, Q., Brito, H.C., Alves, P.B., Pavao-Zuckerman, M.A., Rufino, I.A., and Hendricks, M.D. (2024). “GIS-based spatial approaches to refining urban catchment delineation that integrate stormwater network infrastructure.” Discover Water, Vol. 4, No. 1, 24.

10.1007/s43832-024-00083-z
21

U.S. Environmental Protection Agency (EPA) (2015). Storm water management model user’s manual version 5.1. EPA/600/R-14/413b, Washington, D.C., U.S.

22

Wei, H., Wu, H., Zhang, L., and Liu, J. (2024). “Urban flooding simulation and flood risk assessment based on the InfoWorks ICM model: A case study of the urban inland rivers in Zhengzhou, China.” Water Science & Technology, Vol. 90, No. 4, pp. 1338-1358.

10.2166/wst.2024.280
23

Woo, H., Sim, S.B., Kim, H.J., Kim, H., and Noh, S.J. (2025). “Urban inundation prediction with an HC-SURF-trained gated-CNN surrogate: The Sillim drainage district case study.” Journal of Korea Water Resources Association, Vol. 58, No. 11, pp. 1099-1111.

10.3741/JKWRA.2025.58.11.1099
Information
  • Publisher :KOREA WATER RESOURECES ASSOCIATION
  • Publisher(Ko) :한국수자원학회
  • Journal Title :Journal of Korea Water Resources Association
  • Journal Title(Ko) :한국수자원학회 논문집
  • Volume : 59
  • No :2
  • Pages :201-212
  • Received Date : 2025-12-01
  • Revised Date : 2025-12-30
  • Accepted Date : 2026-01-09
  • DOI :https://doi.org/10.3741/JKWRA.2026.59.2.201
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