Timing the time of concentration: shedding light on a paradox

E. Michailidi, S. Antoniadi, A. Koukouvinos, B. Bacchi, and A. Efstratiadis, Timing the time of concentration: shedding light on a paradox, Hydrological Sciences Journal, 63 (5), 721–740, doi:10.1080/02626667.2018.1450985, 2018.



From the origins of hydrology, the time of concentration, tc, has been conventionally tackled as constant quantity. However, theoretical proof and empirical evidence imply that tc exhibits significant variability against rainfall, making its definition and estimation a hydrological paradox. Adopting the assumptions of the Rational method and the kinematic approach, an effective procedure in a GIS environment for estimating the travel time across a catchment’s longest flow path is provided. By applying it in 30 Mediterranean basins, it is illustrated that tc is a negative power function of excess rainfall intensity. Regional formulas are established to infer its multiplier (unit time of concentration) and exponent from abstract geomorphological information, which are validated against observed data and theoretical literature outcomes. Besides offering a fast and easy solution to the paradox, we highlight the necessity for implementing the varying tc concept within hydrological modelling, signalling a major shift from current engineering practices.

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2020 Tison Award, by International Association of Hydrological Sciences, awared to young hydrologists Eleni Maria Michailidi and Sylvia Antoniadi (https://iahs.info/About-IAHS/Competition--Events/Tison-Award/Tison-Award-winners/EMichailidi-SAntoniadi/)

Our works referenced by this work:

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