This study aims to show the ability of 1D model to simulate the wadi flow during the flood. The wadi is a semiarid stream characterized by the non uniform geometry and an intermittent flow. These complexities can be modelled by a robust 1D model such as Rubarbe. In this article we study the 1994 flood of Ksob wadi that caused a large inundation of M’sila town in the center of Algeria. The simulated reach located downstream the Ksob dam, crosses M’sila over a length of 6800 m with a bed slope of 0.6 %. The recorded flow peak of the 1994 flood is about 1430 m3/s and flood duration is 24 days. The flood propagation is simulated through the studied reach using the Rubarbe code (1D model) developed in Irstea (former Cemagref). The results show that the wadi overflows in some sections at the upstream and the center of the reach. The major part of the overflow is observed just around the peak of the flood, but the duration is variable from a few minutes to several hours. The overflow hazard limits are plotted in each section from the intersections of the highest water elevation recorded during the flood with the ground level of the two banks of the same section, taking into account the floodplain slope. According to our investigations, the calculated flooded area is very close to the real one, especially in the central part of the reach.