Exchange between drainage systems and surface flows during urban flooding: Quasi-steady and dynamic modelling in unsteady flow conditions

Vasileios Kitsikoudis, Sebastien Erpicum, Matteo Rubinato, James Shucksmith, Pierre Archambeau, Michel Pirotton, Benjamin Dewals

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)
38 Downloads (Pure)


The accurate modelling of urban flooding constitutes an integral part of flood risk assessment and management in residential and industrial areas. Interactions between drainage networks and surface runoff flows are commonly modelled based on weir/orifice equations; however, this approach has not been satisfactorily validated in unsteady flow conditions due to uncertainties in estimating the discharge coefficients and associated head losses. This study utilises experimental data of flow exchange between the sewer flow and the floodplain through a manhole without a lid to develop two alternate approaches that simulate this interaction and describe the associated exchange flow. A quasi-steady model links the exchange flow to the total head in the sewer pipe and the head losses in the sewer and the manhole, whilst a dynamic model takes also into account the evolution of the water level within the manhole at discrete time steps. The developed numerical models are subsequently validated against large-scale experimental data for unsteady sewer flow conditions, featuring variable exchange to the surface. Results confirmed that both models can accurately replicate experimental conditions, with improved performance when compared to existing methodologies based only on weir or orifice equations.
Original languageEnglish
Article number126628
Number of pages11
JournalJournal of Hydrology
Early online date10 Jul 2021
Publication statusPublished - Nov 2021

Bibliographical note

This is an open access article under the CC BY license (


This research was supported by the UK Engineering and Physical Sciences Research Council (EP/K040405/1).


  • Drainage systems
  • Head losses
  • Sewer/surface flow interactions
  • Unsteady flow
  • Urban flood modelling
  • Urban hydraulics

ASJC Scopus subject areas

  • Water Science and Technology


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