We consider the dam break problem upon an inclined plane. The flow of a series of Newtonian fluids is generated by the collapse of a dam in a completely transparent channel with variable slope. The stage at given abscissa and the front wave evolution are accurately investigated using ultrasonic and image analysis facilities respectively. While the Navier Stokes and the continuity equations are properly rendered non dfmensional in the viscous regine and solved with the ID shallow water approximation. A successful comparison is shown between the experimental and the theoretical results.