Fluid Avalanches on a Laboratory Scale.

We will summarize theoretical approaches used to describe the motion of an avalanching mass down a steep slope. Focus is given to Newtonian and viscoplastic fluids. The governing equation can be obtained by assuming that the flow-depth to length ratio is small, which allows to simplifying a great deal the Navier-Stokes equations. Self-similar solutions to the governing equation can be worked out for early and late times. We compare our experimental data with these solutions