Modelling of individual debris flows using Flow-R: A case study in four Swiss torrents

Florian von Fischer, Margreth Keiler and Markus Zimmermann

Recently, an empirical debris flow model called Flow-R has been added to the broad range of existing debris flow modelling software. While Flow-Râs applicability on regional scale has been confirmed in several studies, itâs potential in local debris flow modelling has not yet been evaluated. In this study, Flow-Râs potential in debris flow modelling on local scale is tested via an application in four debris flow torrents in Switzerland. Obtained results are validated by comparison to documented debris flow events as well as model results from the commonly used hydraulic debris flow model RAMMS. Results show that due to the nonhydraulic model conception, the potential of Flow-R in individual debris flow modelling is limited. Plausible debris flow patterns are only achieved on torrents showing a low to moderate channelization, i.e. incision on the fan. Computed process velocities are unreliable due to the inability of the model to account for debris flow mass. Moreover, modelled debris flow magnitudes are biased by the compulsory non-volumetric definition of magnitudes.

2016/1 257-258