On the need for larger Manning's roughness coefficients in depth-integrated tsunami inundation models

Jeremy D. Bricker, Stanford Gibson, Hiroshi Takagi, Fumihiko Imamura

    Research output: Contribution to journalArticlepeer-review

    66 Citations (Scopus)

    Abstract

    Manning's n values for open channel (river) flow have been studied by hydraulic engineers since the late 19th century, and a rich literature exists on the topic including large-scale laboratory experiments and actual field measurements. Both river flood models and shallow water equation tsunami inundation models incorporate the importance of varying equivalent roughness values with the large-scale roughness elements present for different land use types. However, many tsunami models (especially in Japan) use n values based on a very limited set of small-scale model laboratory experiments with inappropriate Reynolds and Weber numbers, instead of using Manning's n values from the open channel flow literature. Due to this, equivalent Manning's n values for vegetated and urban areas in these tsunami inundation models are too small, causing the mitigating effect of forests and urban regions to be underestimated. This paper presents a review of Manning's n research applied to both river flood and tsunami inundation models, and suggests values to improve the reliability of the latter.

    Original languageEnglish
    Article number1550005
    JournalCoastal Engineering Journal
    Volume57
    Issue number2
    DOIs
    Publication statusPublished - 2015 Jun 20

    Keywords

    • Manning's n
    • Tsunami inundation model
    • friction
    • land-use
    • roughness

    ASJC Scopus subject areas

    • Civil and Structural Engineering
    • Modelling and Simulation
    • Ocean Engineering

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