Full 2D hydrodynamic modelling of rainfall-induced flash floods

Wei Huang, Zhi xian Cao, Wen jun Qi, Gareth Pender, Kai Zhao

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Mountain catchments are prone to flash flooding due to heavy rainfall. Enhanced understanding of the generation and evolution processes of flash floods is essential for effective flood risk management. However, traditional distributed hydrological models based on kinematic and diffusion wave approximations ignore certain physical mechanisms of flash floods and thus bear excessive uncertainty. Here a hydrodynamic model is presented for flash floods based on the full two-dimensional shallow water equations incorporating rainfall and infiltration. Laboratory experiments of overland flows were modelled to illustrate the capability of the model. Then the model was applied to resolve two observed flash floods of distinct magnitudes in the Lengkou catchment in Shanxi Province, China. The present model is shown to be able to reproduce the flood flows fairly well compared to the observed data. The spatial distribution of rainfall is shown to be crucial for the modelling of flash floods. Sensitivity analyses of the model parameters reveal that the stage and discharge hydrographs are more sensitive to the Manning roughness and initial water content in the catchment than to the Green-Ampt head. Most notably, as the flash flood augments due to heavier rainfall, the modelling results agree with observed data better, which clearly characterizes the paramount role of rainfall in dictating the floods. From practical perspectives, the proposed model is more appropriate for modelling large flash floods.

Original languageEnglish
Pages (from-to)1203-1218
Number of pages16
JournalJournal of Mountain Science
Volume12
Issue number5
Early online date29 Sep 2015
DOIs
Publication statusPublished - Sep 2015

Keywords

  • Flash flood
  • Full hydrodynamic model
  • Rainfall
  • Spatial distribution

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geography, Planning and Development
  • Geology
  • Global and Planetary Change
  • Nature and Landscape Conservation

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