Development of a numerical model for debris flow over steep slope terrain near the suburbs and urban area

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Tuesday 30 june 2015

13:00 - 13:03h at Europe 1 & 2 (level 0)

Themes: (T) Water engineering, (ST) Computational methods, Poster pitches

Parallel session: Poster pitches: 5E. Engineering - Computional

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Debris flows are unsteady flow phenomena in which the flow changes rapidly, and cause significant damage to properties and loss of lives, since they often occur in those parts of the suburbs and urban area that are most utilized by human activities. However, hydrodynamic modeling of debris flows still suffers difficulties due to the complex behavior of debris flow process and large variability of material composition. In this study, a numerical model for the debris flow analysis was developed with emphasis on (1) the flow resistance relations with 9 bottom shear stress options; (2) a total gravity concept to activate the vertical flow motion accelerated on steep slope; (3) an apparent eddy viscosity approach to cover the rheological properties of viscoplastic Non-Newtonian fluid; and (4) the addition of source term to the continuity equation to include the mass increase by entrainment of mobilized bulk materials on the bottom during the transport processes. To these ends, shallow water equations were modified, and Petrov-Galerking stabilization scheme was employed to consider complex geomorphology in the suburbs and urban areas. The developed model was applied to various debris flow problems ranging from dam break flow with analytical solutions, USGS experimental flumes (Iverson et al., 2010) to field run-out event with observation data (Seoul metropolitan government, 2014). Since physical phenomena of the debris flow were accurately reflected on the mathematical model, the developed debris analysis model for general purposes was found to be very efficient in simulating the transport of mixed mass and computing the extent of damage by use of field input data.