Runout and deposit morphology of Bingham fluid as a function of initial volume: implication for debris flow modelling

Debris flow modelling has become an important tool for assessing the related hazard so as to undertake appropriate mitigation actions and reduce the associated risk. Volume values are key input data for landslides numerical modelling. This work analyses the influence of the uncertainties related to initial volume and initial mass morphology (using the aspect ratio as a parameter) on the spreading of Bingham fluid. The dependency of this effect on slope changes is also analysed using three interesting landscape configurations: a horizontal plane, a simplified bilinear topography with increasing slope angle, and a real topography (Colima volcano landscape). We use the smoothed particle hydrodynamics (SPH) model to carry out this analysis. The SPH model is a depth-integrated model, which was previously validated by reproducing problems with analytical results (1D break dam). The initial aspect ratio is a primordial control parameter of the spreading in the case of a quasi-horizontal plane or very gentle slope, but this effect dissipates when the slope angle increases and the flow dynamics become essentially controlled by its volume. Even if most hydrodynamic models using different rheological approach can successfully reproduce real events, input data uncertainties and model sensitivity should be taken into account. Copyright Springer Science+Business Media Dordrecht 2015