For uniform particle size distribution

${\tau }^{*}<0.027$

The grains are at rest on a flat bottom

$0.027<{\tau }^{*}<0.047$

Appearance of the very first movements, but not enough to generate a solid flow

$0.047<{\tau }^{*}<0.062$

Carriage on flat bottom

$0.062<{\tau }^{*}<0.25$

Carriage by dunes

$0.25<{\tau }^{*}<2.5$

Transport in suspension by dune

${\tau }^{*}>2.5$

Transport in suspension in a flat bottom