The importance of gully flow modelling to urban flood simulation

Jiun Huei Jang, Chi Tai Hsieh, Tien Hao Chang

Research output: Contribution to journalArticle


Urban flood simulation often ignores or simplifies the function of underground gully systems due to data and computational limitations. To discover the influence of gullies on urban flooding, a novel approach is proposed in this study, by fully-coupling a 1D gully flow model (GFM), a 1D sewer flow model (SFM), and a 2D overland flow model (OFM) to simultaneously simulate the flow exchanges between surface, gullies and sewer pipes. This fully-coupled approach is compared with a simplified approach which directly introduces surface water into sewer pipes without being via gullies. The validation results show that the fully-coupled approach considerably reduces the underestimation of flood extent by 27% compared with the simplified approach. Without considering the capacity of lateral tubes between gullies and sewer pipes, the simplified approach over-drains the surface water into sewer pipes. The modelling of gully flow is crucial for correctly evaluating the efficiency of drainage systems.

Original languageEnglish
Pages (from-to)377-388
Number of pages12
JournalUrban Water Journal
Issue number5
Publication statusPublished - 2019 May 28

All Science Journal Classification (ASJC) codes

  • Geography, Planning and Development
  • Water Science and Technology

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