A mobile flood protection barrier system for quickly stopping and damming back watercourses, overflows, and for raising the embankment in flood protection as a temporary facility. The system has water-fillable water storage units that are connected to one another and supporting structures, the water storage units are placed into the triangular supporting frames of the supporting structure and fixed to supporting structure, to the spacer bar thereof. The water storage unit is made of a single, continuous, rectangular flexible material, divided into three parts by longitudinal folds, has a triangular prism-shape in the filled-up state, with the surface of the middle folded part in contact with the soil, and is open along its upper edges. The lateral ends of the water storage unit are partially closed. The water storage units can be connected to one another via unit coupling extension portions made from their own material.