  The theory of a flux steady-state (avalanche) formation is presented for the
simplest model of a real sand pile within the framework of Lorenz approach. The
stationary values of sand velocity and sand pile slope are derived as functions
of controlling parameter (externally driven sandpile slope). The additive
noises of above values are taken into account to build the phase diagram, where
the noise intensities determine a domain of the avalanche appearance. This
domain shows to be crucial to the noise intensity of vertical component of sand
velocity.
